+-----------+----------------------------------------------------------+
| ![](m     | **Human Factors Phase III:\                              |
| edia/imag | Effects of Train Control Technology on Operator          |
| e1.wmf){w | Performance**                                            |
| idth="2.9 |                                                          |
| 895833333 |                                                          |
| 333335in" |                                                          |
| height="  |                                                          |
| 1.4486111 |                                                          |
| 11111111i |                                                          |
| n"}![](me |                                                          |
| dia/image |                                                          |
| 2.wmf){wi |                                                          |
| dth="0.46 |                                                          |
| 111111111 |                                                          |
| 111114in" |                                                          |
| hei       |                                                          |
| ght="0.50 |                                                          |
| 347222222 |                                                          |
| 22222in"} |                                                          |
|           |                                                          |
| U.S.      |                                                          |
| D         |                                                          |
| epartment |                                                          |
|           |                                                          |
| of        |                                                          |
| Trans     |                                                          |
| portation |                                                          |
|           |                                                          |
| **Federal |                                                          |
| R         |                                                          |
| ailroad** |                                                          |
|           |                                                          |
| **Adminis |                                                          |
| tration** |                                                          |
+-----------+----------------------------------------------------------+

+----------------------+-----------------------------------------------+
| Office of Research   | U.S. Department of Transportation             |
|                      |                                               |
| and Development      | Research and Special Programs Administration  |
|                      |                                               |
| Washington, DC 20590 | John A. Volpe National Transportation Systems |
|                      | Center                                        |
|                      |                                               |
|                      | Cambridge, MA 02142                           |
+----------------------+-----------------------------------------------+

![](media/image3.png){width="5.5in" height="3.251388888888889in"}

+------------------------+--------------------+------------------------+
| DOT/FRA/ORD-04/18      | > Final Report     | This document is       |
|                        | >                  | available to the       |
|                        | > January 2005     |                        |
|                        |                    | public through the     |
|                        |                    | National Technical     |
|                        |                    |                        |
|                        |                    | Information Service,   |
|                        |                    | Springfield, VA 22161  |
|                        |                    |                        |
|                        |                    | This document is also  |
|                        |                    | available on           |
|                        |                    |                        |
|                        |                    | the FRA website at     |
|                        |                    | www.fra.dot.gov        |
+------------------------+--------------------+------------------------+

+-----------------------------------------------------------------------+
| > Notice                                                              |
|                                                                       |
| This document is disseminated under the sponsorship of the Department |
| of Transportation in the interest of information exchange. The United |
| States Government assumes no liability for its contents or use        |
| thereof.                                                              |
+-----------------------------------------------------------------------+
|                                                                       |
+-----------------------------------------------------------------------+
| > Notice                                                              |
|                                                                       |
| The United States Government does not endorse products or             |
| manufacturers. Trade or manufacturers' names appear herein solely     |
| because they are considered essential to the objective of this        |
| report.                                                               |
+-----------------------------------------------------------------------+

+------------------+---+--------------+---+-------+---+---+--------------+
| **REPORT         |   |              |   |       | * |   |              |
| DOCUMENTATION    |   |              |   |       | F |   |              |
| PAGE**           |   |              |   |       | o |   |              |
|                  |   |              |   |       | r |   |              |
|                  |   |              |   |       | m |   |              |
|                  |   |              |   |       | A |   |              |
|                  |   |              |   |       | p |   |              |
|                  |   |              |   |       | p |   |              |
|                  |   |              |   |       | r |   |              |
|                  |   |              |   |       | o |   |              |
|                  |   |              |   |       | v |   |              |
|                  |   |              |   |       | e |   |              |
|                  |   |              |   |       | d |   |              |
|                  |   |              |   |       | * |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       | * |   |              |
|                  |   |              |   |       | O |   |              |
|                  |   |              |   |       | M |   |              |
|                  |   |              |   |       | B |   |              |
|                  |   |              |   |       | N |   |              |
|                  |   |              |   |       | o |   |              |
|                  |   |              |   |       | . |   |              |
|                  |   |              |   |       | 0 |   |              |
|                  |   |              |   |       | 7 |   |              |
|                  |   |              |   |       | 0 |   |              |
|                  |   |              |   |       | 4 |   |              |
|                  |   |              |   |       | - |   |              |
|                  |   |              |   |       | 0 |   |              |
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|                  |   |              |   |       | 8 |   |              |
|                  |   |              |   |       | 8 |   |              |
|                  |   |              |   |       | * |   |              |
+------------------+---+--------------+---+-------+---+---+--------------+
| Public reporting |   |              |   |       |   |   |              |
| burden for this  |   |              |   |       |   |   |              |
| collection of    |   |              |   |       |   |   |              |
| information is   |   |              |   |       |   |   |              |
| estimated to     |   |              |   |       |   |   |              |
| average 1 hour   |   |              |   |       |   |   |              |
| per response,    |   |              |   |       |   |   |              |
| including the    |   |              |   |       |   |   |              |
| time for         |   |              |   |       |   |   |              |
| reviewing        |   |              |   |       |   |   |              |
| instructions,    |   |              |   |       |   |   |              |
| searching        |   |              |   |       |   |   |              |
| existing data    |   |              |   |       |   |   |              |
| sources,         |   |              |   |       |   |   |              |
| gathering and    |   |              |   |       |   |   |              |
| maintaining the  |   |              |   |       |   |   |              |
| data needed and  |   |              |   |       |   |   |              |
| completing and   |   |              |   |       |   |   |              |
| reviewing the    |   |              |   |       |   |   |              |
| collection of    |   |              |   |       |   |   |              |
| information.     |   |              |   |       |   |   |              |
| Send comments    |   |              |   |       |   |   |              |
| regarding this   |   |              |   |       |   |   |              |
| burden estimate  |   |              |   |       |   |   |              |
| or any aspects   |   |              |   |       |   |   |              |
| of this          |   |              |   |       |   |   |              |
| collection of    |   |              |   |       |   |   |              |
| information ,    |   |              |   |       |   |   |              |
| including        |   |              |   |       |   |   |              |
| suggestions for  |   |              |   |       |   |   |              |
| reducing this    |   |              |   |       |   |   |              |
| burden to        |   |              |   |       |   |   |              |
| Washington       |   |              |   |       |   |   |              |
| Headquarters     |   |              |   |       |   |   |              |
| Service,         |   |              |   |       |   |   |              |
| Directorate for  |   |              |   |       |   |   |              |
| information      |   |              |   |       |   |   |              |
| Operations and   |   |              |   |       |   |   |              |
| Reports. 1215    |   |              |   |       |   |   |              |
| Jefferson Davis  |   |              |   |       |   |   |              |
| Highway, Suite   |   |              |   |       |   |   |              |
| 1204, Arlington, |   |              |   |       |   |   |              |
| VA. 222202-4302, |   |              |   |       |   |   |              |
| and to the       |   |              |   |       |   |   |              |
| Office of        |   |              |   |       |   |   |              |
| Management and   |   |              |   |       |   |   |              |
| Budget,          |   |              |   |       |   |   |              |
| Paperwork        |   |              |   |       |   |   |              |
| Reduction        |   |              |   |       |   |   |              |
| Project          |   |              |   |       |   |   |              |
| (0704-0188),     |   |              |   |       |   |   |              |
| Washington, DC   |   |              |   |       |   |   |              |
| 20503.           |   |              |   |       |   |   |              |
+------------------+---+--------------+---+-------+---+---+--------------+
| 1\. Agency Use   |   | 2.  Report   |   | 3.  R |   |   |              |
| Only (*Leave     |   |     Date     |   | EPORT |   |   |              |
| blank*)          |   |              |   |       |   |   |              |
|                  |   | January 2005 |   |  TYPE |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |   AND |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   | DATES |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |    CO |   |   |              |
|                  |   |              |   | VERED |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   | Final |   |   |              |
|                  |   |              |   | R     |   |   |              |
|                  |   |              |   | eport |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   | A     |   |   |              |
|                  |   |              |   | ugust |   |   |              |
|                  |   |              |   | 1     |   |   |              |
|                  |   |              |   | 993 - |   |   |              |
|                  |   |              |   | July  |   |   |              |
|                  |   |              |   | 1997  |   |   |              |
+------------------+---+--------------+---+-------+---+---+--------------+
| 4.  Title and    |   |              |   |       | 5 |   |              |
|     subtitle     |   |              |   |       | . |   |              |
|                  |   |              |   |       |   |   |              |
| Human Factors    |   |              |   |       |   |   |              |
| Phase III:       |   |              |   |       | F |   |              |
| Effects of Train |   |              |   |       | U |   |              |
| Control          |   |              |   |       | N |   |              |
| Technology on    |   |              |   |       | D |   |              |
| Operator         |   |              |   |       | I |   |              |
| Performance      |   |              |   |       | N |   |              |
|                  |   |              |   |       | G |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       | N |   |              |
|                  |   |              |   |       | U |   |              |
|                  |   |              |   |       | M |   |              |
|                  |   |              |   |       | B |   |              |
|                  |   |              |   |       | E |   |              |
|                  |   |              |   |       | R |   |              |
|                  |   |              |   |       | S |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       | R |   |              |
|                  |   |              |   |       | 2 |   |              |
|                  |   |              |   |       | 1 |   |              |
|                  |   |              |   |       | 0 |   |              |
|                  |   |              |   |       | 3 |   |              |
|                  |   |              |   |       | / |   |              |
|                  |   |              |   |       | R |   |              |
|                  |   |              |   |       | R |   |              |
|                  |   |              |   |       | 2 |   |              |
|                  |   |              |   |       | 0 |   |              |
|                  |   |              |   |       | 4 |   |              |
+------------------+---+--------------+---+-------+---+---+--------------+
| 6.  AUTHOR(S)    |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
| Edward J.        |   |              |   |       |   |   |              |
| Lanzilotta and   |   |              |   |       |   |   |              |
| Thomas B.        |   |              |   |       |   |   |              |
| Sheridan         |   |              |   |       |   |   |              |
+------------------+---+--------------+---+-------+---+---+--------------+
| 7.  PERFORMING   |   |              |   |       | 8 |   |              |
|     ORGANIZATION |   |              |   |       | . |   |              |
|     NAME(S) AND  |   |              |   |       |   |   |              |
|     ADDRESS(ES)  |   |              |   |       |   |   |              |
|                  |   |              |   |       | P |   |              |
| \*Human-Machine  |   |              |   |       | E |   |              |
| Systems          |   |              |   |       | R |   |              |
| Laboratory       |   |              |   |       | F |   |              |
|                  |   |              |   |       | O |   |              |
| Massachusetts    |   |              |   |       | R |   |              |
| Institute of     |   |              |   |       | M |   |              |
| Technology       |   |              |   |       | I |   |              |
|                  |   |              |   |       | N |   |              |
| Cambridge, MA    |   |              |   |       | G |   |              |
| 02139            |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       | O |   |              |
|                  |   |              |   |       | R |   |              |
|                  |   |              |   |       | G |   |              |
|                  |   |              |   |       | A |   |              |
|                  |   |              |   |       | N |   |              |
|                  |   |              |   |       | I |   |              |
|                  |   |              |   |       | Z |   |              |
|                  |   |              |   |       | A |   |              |
|                  |   |              |   |       | T |   |              |
|                  |   |              |   |       | I |   |              |
|                  |   |              |   |       | O |   |              |
|                  |   |              |   |       | N |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       | D |   |              |
|                  |   |              |   |       | O |   |              |
|                  |   |              |   |       | T |   |              |
|                  |   |              |   |       | - |   |              |
|                  |   |              |   |       | V |   |              |
|                  |   |              |   |       | N |   |              |
|                  |   |              |   |       | T |   |              |
|                  |   |              |   |       | S |   |              |
|                  |   |              |   |       | C |   |              |
|                  |   |              |   |       | - |   |              |
|                  |   |              |   |       | F |   |              |
|                  |   |              |   |       | R |   |              |
|                  |   |              |   |       | A |   |              |
|                  |   |              |   |       | - |   |              |
|                  |   |              |   |       | 0 |   |              |
|                  |   |              |   |       | 5 |   |              |
|                  |   |              |   |       | - |   |              |
|                  |   |              |   |       | 0 |   |              |
|                  |   |              |   |       | 1 |   |              |
+------------------+---+--------------+---+-------+---+---+--------------+
| 9.  SPONS        |   |              |   |       | 1 |   |              |
| ORING/MONITORING |   |              |   |       | 0 |   |              |
|     AGENCY       |   |              |   |       | . |   |              |
|     NAME(S) AND  |   |              |   |       |   |   |              |
|     ADDRESS(ES)  |   |              |   |       | S |   |              |
|                  |   |              |   |       | P |   |              |
| U.S. Department  |   |              |   |       | O |   |              |
| of               |   |              |   |       | N |   |              |
| Transportation   |   |              |   |       | S |   |              |
|                  |   |              |   |       | O |   |              |
| Federal Railroad |   |              |   |       | R |   |              |
| Administration   |   |              |   |       | I |   |              |
|                  |   |              |   |       | N |   |              |
| Office of        |   |              |   |       | G |   |              |
| Research and     |   |              |   |       | / |   |              |
| Development Mail |   |              |   |       | M |   |              |
| Stop 20          |   |              |   |       | O |   |              |
|                  |   |              |   |       | N |   |              |
| 1120 Vermont     |   |              |   |       | I |   |              |
| Avenue, NW       |   |              |   |       | T |   |              |
|                  |   |              |   |       | O |   |              |
| Washington, DC   |   |              |   |       | R |   |              |
| 20590            |   |              |   |       | I |   |              |
|                  |   |              |   |       | N |   |              |
|                  |   |              |   |       | G |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       | A |   |              |
|                  |   |              |   |       | G |   |              |
|                  |   |              |   |       | E |   |              |
|                  |   |              |   |       | N |   |              |
|                  |   |              |   |       | C |   |              |
|                  |   |              |   |       | Y |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       | R |   |              |
|                  |   |              |   |       | E |   |              |
|                  |   |              |   |       | P |   |              |
|                  |   |              |   |       | O |   |              |
|                  |   |              |   |       | R |   |              |
|                  |   |              |   |       | T |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       | N |   |              |
|                  |   |              |   |       | U |   |              |
|                  |   |              |   |       | M |   |              |
|                  |   |              |   |       | B |   |              |
|                  |   |              |   |       | E |   |              |
|                  |   |              |   |       | R |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       | D |   |              |
|                  |   |              |   |       | O |   |              |
|                  |   |              |   |       | T |   |              |
|                  |   |              |   |       | / |   |              |
|                  |   |              |   |       | F |   |              |
|                  |   |              |   |       | R |   |              |
|                  |   |              |   |       | A |   |              |
|                  |   |              |   |       | / |   |              |
|                  |   |              |   |       | O |   |              |
|                  |   |              |   |       | R |   |              |
|                  |   |              |   |       | D |   |              |
|                  |   |              |   |       | - |   |              |
|                  |   |              |   |       | 0 |   |              |
|                  |   |              |   |       | 4 |   |              |
|                  |   |              |   |       | / |   |              |
|                  |   |              |   |       | 1 |   |              |
|                  |   |              |   |       | 8 |   |              |
+------------------+---+--------------+---+-------+---+---+--------------+
| 1                |   |              |   |       |   |   |              |
| 1. SUPPLEMENTARY |   |              |   |       |   |   |              |
|     NOTES        |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
| Safety of High   |   |              |   |       |   |   |              |
| Speed Ground     |   |              |   |       |   |   |              |
| Transportation   |   |              |   |       |   |   |              |
| Systems Series   |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
| \* Under         |   |              |   |       |   |   |              |
| Contract to:     |   |              |   |       |   |   |              |
| U.S. Department  |   |              |   |       |   |   |              |
| of               |   |              |   |       |   |   |              |
| Transportation   |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
| Research and     |   |              |   |       |   |   |              |
| Special Programs |   |              |   |       |   |   |              |
| Administration   |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
| John A. Volpe    |   |              |   |       |   |   |              |
| National         |   |              |   |       |   |   |              |
| Transportation   |   |              |   |       |   |   |              |
| Systems Center   |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
| Cambridge, MA    |   |              |   |       |   |   |              |
| 02142-1093       |   |              |   |       |   |   |              |
+------------------+---+--------------+---+-------+---+---+--------------+
| 12a.             |   |              |   |       | 1 |   |              |
| DISTRIBUT        |   |              |   |       | 2 |   |              |
| ION/AVAILABILITY |   |              |   |       | b |   |              |
| STATEMENT        |   |              |   |       | . |   |              |
|                  |   |              |   |       | D |   |              |
| This document is |   |              |   |       | I |   |              |
| available to the |   |              |   |       | S |   |              |
| public through   |   |              |   |       | T |   |              |
| the National     |   |              |   |       | R |   |              |
| Technical        |   |              |   |       | I |   |              |
| Information      |   |              |   |       | B |   |              |
| Service,         |   |              |   |       | U |   |              |
| Springfield, VA  |   |              |   |       | T |   |              |
| 22161. This      |   |              |   |       | I |   |              |
| document is also |   |              |   |       | O |   |              |
| available on the |   |              |   |       | N |   |              |
| FRA web site at  |   |              |   |       | C |   |              |
| www.fra.dot.gov. |   |              |   |       | O |   |              |
|                  |   |              |   |       | D |   |              |
|                  |   |              |   |       | E |   |              |
+------------------+---+--------------+---+-------+---+---+--------------+
| 13. ABSTRACT     |   |              |   |       |   |   |              |
|     (Maximum 200 |   |              |   |       |   |   |              |
|     words)       |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
| This report      |   |              |   |       |   |   |              |
| describes a      |   |              |   |       |   |   |              |
| study evaluating |   |              |   |       |   |   |              |
| the effects of   |   |              |   |       |   |   |              |
| train control    |   |              |   |       |   |   |              |
| technology on    |   |              |   |       |   |   |              |
| locomotive       |   |              |   |       |   |   |              |
| engineer         |   |              |   |       |   |   |              |
| performance.     |   |              |   |       |   |   |              |
| Several types of |   |              |   |       |   |   |              |
| train control    |   |              |   |       |   |   |              |
| systems were     |   |              |   |       |   |   |              |
| evaluated:       |   |              |   |       |   |   |              |
| partial          |   |              |   |       |   |   |              |
| automation       |   |              |   |       |   |   |              |
| (cruise control  |   |              |   |       |   |   |              |
| and programmed   |   |              |   |       |   |   |              |
| stop) and full   |   |              |   |       |   |   |              |
| automation were  |   |              |   |       |   |   |              |
| compared to      |   |              |   |       |   |   |              |
| manual train     |   |              |   |       |   |   |              |
| control. The     |   |              |   |       |   |   |              |
| study evaluated  |   |              |   |       |   |   |              |
| how these        |   |              |   |       |   |   |              |
| systems affected |   |              |   |       |   |   |              |
| human            |   |              |   |       |   |   |              |
| performance      |   |              |   |       |   |   |              |
| related to       |   |              |   |       |   |   |              |
| position         |   |              |   |       |   |   |              |
| control, speed   |   |              |   |       |   |   |              |
| regulation and   |   |              |   |       |   |   |              |
| response to      |   |              |   |       |   |   |              |
| system failures, |   |              |   |       |   |   |              |
| using a          |   |              |   |       |   |   |              |
| h                |   |              |   |       |   |   |              |
| uman-in-the-loop |   |              |   |       |   |   |              |
| locomotive       |   |              |   |       |   |   |              |
| simulator.       |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
| The study found  |   |              |   |       |   |   |              |
| a significant    |   |              |   |       |   |   |              |
| difference in    |   |              |   |       |   |   |              |
| the variance of  |   |              |   |       |   |   |              |
| response times   |   |              |   |       |   |   |              |
| to brake         |   |              |   |       |   |   |              |
| failures and     |   |              |   |       |   |   |              |
| traction motor   |   |              |   |       |   |   |              |
| failures for the |   |              |   |       |   |   |              |
| partial          |   |              |   |       |   |   |              |
| automation       |   |              |   |       |   |   |              |
| condition        |   |              |   |       |   |   |              |
| compared to      |   |              |   |       |   |   |              |
| manual and full  |   |              |   |       |   |   |              |
| automation       |   |              |   |       |   |   |              |
| conditions. In   |   |              |   |       |   |   |              |
| this condition,  |   |              |   |       |   |   |              |
| participants     |   |              |   |       |   |   |              |
| biased toward    |   |              |   |       |   |   |              |
| monitoring       |   |              |   |       |   |   |              |
| events outside   |   |              |   |       |   |   |              |
| the locomotive   |   |              |   |       |   |   |              |
| instead of the   |   |              |   |       |   |   |              |
| instrument       |   |              |   |       |   |   |              |
| panel.           |   |              |   |       |   |   |              |
+------------------+---+--------------+---+-------+---+---+--------------+
| 14. SUBJECT      |   |              |   |       |   | 1 |              |
|     TERMS        |   |              |   |       |   | 5 |              |
|                  |   |              |   |       |   | . |              |
|     automation,  |   |              |   |       |   |   |              |
|     high-speed   |   |              |   |       |   | N |              |
|     trains,      |   |              |   |       |   | U |              |
|     human        |   |              |   |       |   | M |              |
|     factors,     |   |              |   |       |   | B |              |
|     h            |   |              |   |       |   | E |              |
| uman-in-the-loop |   |              |   |       |   | R |              |
|     simulation,  |   |              |   |       |   |   |              |
|     risk         |   |              |   |       |   |   |              |
|     estimation,  |   |              |   |       |   |   |              |
|     safety,      |   |              |   |       |   |   |              |
|     supervisory  |   |              |   |       |   | O |              |
|     controls,    |   |              |   |       |   | F |              |
|     train        |   |              |   |       |   |   |              |
|     control,     |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|   transportation |   |              |   |       |   |   |              |
|                  |   |              |   |       |   | P |              |
|                  |   |              |   |       |   | A |              |
|                  |   |              |   |       |   | G |              |
|                  |   |              |   |       |   | E |              |
|                  |   |              |   |       |   | S |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   | 8 |              |
|                  |   |              |   |       |   | 8 |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   | 1 |              |
|                  |   |              |   |       |   | 6 |              |
|                  |   |              |   |       |   | . |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   | P |              |
|                  |   |              |   |       |   | R |              |
|                  |   |              |   |       |   | I |              |
|                  |   |              |   |       |   | C |              |
|                  |   |              |   |       |   | E |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   | C |              |
|                  |   |              |   |       |   | O |              |
|                  |   |              |   |       |   | D |              |
|                  |   |              |   |       |   | E |              |
+------------------+---+--------------+---+-------+---+---+--------------+
| 17. SECURITY     | 1 |              | 1 |       |   |   | LIMITATION   |
|                  | 8 |              | 9 |       |   |   | OF ABSTRACT  |
|   CLASSIFICATION | . |              | . |       |   |   |              |
|     OF REPORT    |   |              |   |       |   |   | Unclassified |
|                  | S |              | S |       |   |   |              |
|     Unclassified | E |              | E |       |   |   |              |
|                  | C |              | C |       |   |   |              |
|                  | U |              | U |       |   |   |              |
|                  | R |              | R |       |   |   |              |
|                  | I |              | I |       |   |   |              |
|                  | T |              | T |       |   |   |              |
|                  | Y |              | Y |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  | C |              | C |       |   |   |              |
|                  | L |              | L |       |   |   |              |
|                  | A |              | A |       |   |   |              |
|                  | S |              | S |       |   |   |              |
|                  | S |              | S |       |   |   |              |
|                  | I |              | I |       |   |   |              |
|                  | F |              | F |       |   |   |              |
|                  | I |              | I |       |   |   |              |
|                  | C |              | C |       |   |   |              |
|                  | A |              | A |       |   |   |              |
|                  | T |              | T |       |   |   |              |
|                  | I |              | I |       |   |   |              |
|                  | O |              | O |       |   |   |              |
|                  | N |              | N |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  | O |              | O |       |   |   |              |
|                  | F |              | F |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  | T |              | A |       |   |   |              |
|                  | H |              | B |       |   |   |              |
|                  | I |              | S |       |   |   |              |
|                  | S |              | T |       |   |   |              |
|                  |   |              | R |       |   |   |              |
|                  |   |              | A |       |   |   |              |
|                  |   |              | C |       |   |   |              |
|                  |   |              | T |       |   |   |              |
|                  | P |              |   |       |   |   |              |
|                  | A |              |   |       |   |   |              |
|                  | G |              |   |       |   |   |              |
|                  | E |              |   |       |   |   |              |
|                  |   |              |   |       |   |   |              |
|                  |   |              | U |       |   |   |              |
|                  |   |              | n |       |   |   |              |
|                  |   |              | c |       |   |   |              |
|                  |   |              | l |       |   |   |              |
|                  | U |              | a |       |   |   |              |
|                  | n |              | s |       |   |   |              |
|                  | c |              | s |       |   |   |              |
|                  | l |              | i |       |   |   |              |
|                  | a |              | f |       |   |   |              |
|                  | s |              | i |       |   |   |              |
|                  | s |              | e |       |   |   |              |
|                  | i |              | d |       |   |   |              |
|                  | f |              |   |       |   |   |              |
|                  | i |              |   |       |   |   |              |
|                  | e |              |   |       |   |   |              |
|                  | d |              |   |       |   |   |              |
+------------------+---+--------------+---+-------+---+---+--------------+

NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89)

> Prescribed by ANSI Std. 239-18
>
> 298-102

METRIC/ENGLISH CONVERSION FACTORS

+---------------+---+---+----------------+---------------+---+---+-----------------+
| **ENGLISH TO  |   |   |                | **METRIC TO   |   |   |                 |
| METRIC**      |   |   |                | ENGLISH**     |   |   |                 |
+===============+===+===+================+===============+===+===+=================+
| **LENGTH      |   |   |                | **LENGTH      |   |   |                 |
| (A            |   |   |                | (A            |   |   |                 |
| PPROXIMATE)** |   |   |                | PPROXIMATE)** |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 inch      | * | * |                | **1           | * |   | **0.04 inch     |
| (in)**        | * | * |                | millimeter    | * |   | (in)**          |
|               | = | 2 |                | (mm)**        | = |   |                 |
|               | * | . |                |               | * |   |                 |
|               | * | 5 |                |               | * |   |                 |
|               |   | c |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | n |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | i |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | s |                |               |   |   |                 |
|               |   | ( |                |               |   |   |                 |
|               |   | c |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | ) |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 foot      | * | * |                | **1           | * |   | **0.4 inch      |
| (ft)**        | * | * |                | centimeter    | * |   | (in)**          |
|               | = | 3 |                | (cm)**        | = |   |                 |
|               | * | 0 |                |               | * |   |                 |
|               | * | c |                |               | * |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | n |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | i |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | s |                |               |   |   |                 |
|               |   | ( |                |               |   |   |                 |
|               |   | c |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | ) |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 yard      | * | * |                | **1 meter     | * |   | **3.3 feet      |
| (yd)**        | * | * |                | (m)**         | * |   | (ft)**          |
|               | = | 0 |                |               | = |   |                 |
|               | * | . |                |               | * |   |                 |
|               | * | 9 |                |               | * |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | ( |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | ) |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 mile      | * | * |                | **1 meter     | * |   | **1.1 yards     |
| (mi)**        | * | * |                | (m)**         | * |   | (yd)**          |
|               | = | 1 |                |               | = |   |                 |
|               | * | . |                |               | * |   |                 |
|               | * | 6 |                |               | * |   |                 |
|               |   | k |                |               |   |   |                 |
|               |   | i |                |               |   |   |                 |
|               |   | l |                |               |   |   |                 |
|               |   | o |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | s |                |               |   |   |                 |
|               |   | ( |                |               |   |   |                 |
|               |   | k |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | ) |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
|               |   |   |                | **1 kilometer | * |   | **0.6 mile      |
|               |   |   |                | (km)**        | * |   | (mi)**          |
|               |   |   |                |               | = |   |                 |
|               |   |   |                |               | * |   |                 |
|               |   |   |                |               | * |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **AREA        |   |   |                | **AREA        |   |   |                 |
| (A            |   |   |                | (A            |   |   |                 |
| PPROXIMATE)** |   |   |                | PPROXIMATE)** |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 square    | * | * |                | **1 square    | * |   | **0.16 square   |
| inch (sq in,  | * | * |                | centimeter    | * |   | inch (sq in,    |
| in^2^)**      | = | 6 |                | (cm^2^)**     | = |   | in^2^)**        |
|               | * | . |                |               | * |   |                 |
|               | * | 5 |                |               | * |   |                 |
|               |   | s |                |               |   |   |                 |
|               |   | q |                |               |   |   |                 |
|               |   | u |                |               |   |   |                 |
|               |   | a |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | c |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | n |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | i |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | s |                |               |   |   |                 |
|               |   | ( |                |               |   |   |                 |
|               |   | c |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | ^ |                |               |   |   |                 |
|               |   | 2 |                |               |   |   |                 |
|               |   | ^ |                |               |   |   |                 |
|               |   | ) |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 square    | * | * |                | **1 square    | * |   | **1.2 square    |
| foot (sq ft,  | * | * |                | meter         | * |   | yards (sq yd,   |
| ft^2^)**      | = | 0 |                | (m^2^)**      | = |   | yd^2^)**        |
|               | * | . |                |               | * |   |                 |
|               | * | 0 |                |               | * |   |                 |
|               |   | 9 |                |               |   |   |                 |
|               |   | s |                |               |   |   |                 |
|               |   | q |                |               |   |   |                 |
|               |   | u |                |               |   |   |                 |
|               |   | a |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | ( |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | ^ |                |               |   |   |                 |
|               |   | 2 |                |               |   |   |                 |
|               |   | ^ |                |               |   |   |                 |
|               |   | ) |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 square    | * | * |                | **1 square    | * |   | **0.4 square    |
| yard (sq yd,  | * | * |                | kilometer     | * |   | mile (sq mi,    |
| yd^2^)**      | = | 0 |                | (km^2^)**     | = |   | mi^2^)**        |
|               | * | . |                |               | * |   |                 |
|               | * | 8 |                |               | * |   |                 |
|               |   | s |                |               |   |   |                 |
|               |   | q |                |               |   |   |                 |
|               |   | u |                |               |   |   |                 |
|               |   | a |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | ( |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | ^ |                |               |   |   |                 |
|               |   | 2 |                |               |   |   |                 |
|               |   | ^ |                |               |   |   |                 |
|               |   | ) |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 square    | * | * |                | **10,000      | * |   | **1 hectare     |
| mile (sq mi,  | * | * |                | square meters | * |   | (ha) = 2.5      |
| mi^2^)**      | = | 2 |                | (m^2^)**      | = |   | acres**         |
|               | * | . |                |               | * |   |                 |
|               | * | 6 |                |               | * |   |                 |
|               |   | s |                |               |   |   |                 |
|               |   | q |                |               |   |   |                 |
|               |   | u |                |               |   |   |                 |
|               |   | a |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | k |                |               |   |   |                 |
|               |   | i |                |               |   |   |                 |
|               |   | l |                |               |   |   |                 |
|               |   | o |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | s |                |               |   |   |                 |
|               |   | ( |                |               |   |   |                 |
|               |   | k |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | ^ |                |               |   |   |                 |
|               |   | 2 |                |               |   |   |                 |
|               |   | ^ |                |               |   |   |                 |
|               |   | ) |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 acre =    | * | * |                |               |   |   |                 |
| 0.4 hectare   | * | * |                |               |   |   |                 |
| (he)**        | = | 4 |                |               |   |   |                 |
|               | * | , |                |               |   |   |                 |
|               | * | 0 |                |               |   |   |                 |
|               |   | 0 |                |               |   |   |                 |
|               |   | 0 |                |               |   |   |                 |
|               |   | s |                |               |   |   |                 |
|               |   | q |                |               |   |   |                 |
|               |   | u |                |               |   |   |                 |
|               |   | a |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | t |                |               |   |   |                 |
|               |   | e |                |               |   |   |                 |
|               |   | r |                |               |   |   |                 |
|               |   | s |                |               |   |   |                 |
|               |   | ( |                |               |   |   |                 |
|               |   | m |                |               |   |   |                 |
|               |   | ^ |                |               |   |   |                 |
|               |   | 2 |                |               |   |   |                 |
|               |   | ^ |                |               |   |   |                 |
|               |   | ) |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **MASS -      |   |   |                | **MASS -      |   |   |                 |
| WEIGHT        |   |   |                | WEIGHT        |   |   |                 |
| (A            |   |   |                | (A            |   |   |                 |
| PPROXIMATE)** |   |   |                | PPROXIMATE)** |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 ounce     | * | * |                | **1 gram      | * | * |                 |
| (oz)**        | * | * |                | (gm)**        | * | * |                 |
|               | = | 2 |                |               | = | 0 |                 |
|               | * | 8 |                |               | * | . |                 |
|               | * | g |                |               | * | 0 |                 |
|               |   | r |                |               |   | 3 |                 |
|               |   | a |                |               |   | 6 |                 |
|               |   | m |                |               |   | o |                 |
|               |   | s |                |               |   | u |                 |
|               |   | ( |                |               |   | n |                 |
|               |   | g |                |               |   | c |                 |
|               |   | m |                |               |   | e |                 |
|               |   | ) |                |               |   | ( |                 |
|               |   | * |                |               |   | o |                 |
|               |   | * |                |               |   | z |                 |
|               |   |   |                |               |   | ) |                 |
|               |   |   |                |               |   | * |                 |
|               |   |   |                |               |   | * |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 pound     | * | * |                | **1 kilogram  | * | * |                 |
| (lb)**        | * | * |                | (kg)**        | * | * |                 |
|               | = | 0 |                |               | = | 2 |                 |
|               | * | . |                |               | * | . |                 |
|               | * | 4 |                |               | * | 2 |                 |
|               |   | 5 |                |               |   | p |                 |
|               |   | k |                |               |   | o |                 |
|               |   | i |                |               |   | u |                 |
|               |   | l |                |               |   | n |                 |
|               |   | o |                |               |   | d |                 |
|               |   | g |                |               |   | s |                 |
|               |   | r |                |               |   | ( |                 |
|               |   | a |                |               |   | l |                 |
|               |   | m |                |               |   | b |                 |
|               |   | ( |                |               |   | ) |                 |
|               |   | k |                |               |   | * |                 |
|               |   | g |                |               |   | * |                 |
|               |   | ) |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
|               |   | * |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 short ton | * | * |                | **1 tonne     | * | * |                 |
| = 2,000       | * | * |                | (t)**         | * | * |                 |
| pounds (lb)** | = | 0 |                |               | = | 1 |                 |
|               | * | . |                |               | * | , |                 |
|               | * | 9 |                |               | * | 0 |                 |
|               |   | t |                |               |   | 0 |                 |
|               |   | o |                |               | * | 0 |                 |
|               |   | n |                |               | * | k |                 |
|               |   | n |                |               | = | i |                 |
|               |   | e |                |               | * | l |                 |
|               |   | ( |                |               | * | o |                 |
|               |   | t |                |               |   | g |                 |
|               |   | ) |                |               |   | r |                 |
|               |   | * |                |               |   | a |                 |
|               |   | * |                |               |   | m |                 |
|               |   |   |                |               |   | s |                 |
|               |   |   |                |               |   | ( |                 |
|               |   |   |                |               |   | k |                 |
|               |   |   |                |               |   | g |                 |
|               |   |   |                |               |   | ) |                 |
|               |   |   |                |               |   | * |                 |
|               |   |   |                |               |   | * |                 |
|               |   |   |                |               |   |   |                 |
|               |   |   |                |               |   | * |                 |
|               |   |   |                |               |   | * |                 |
|               |   |   |                |               |   | 1 |                 |
|               |   |   |                |               |   | . |                 |
|               |   |   |                |               |   | 1 |                 |
|               |   |   |                |               |   | s |                 |
|               |   |   |                |               |   | h |                 |
|               |   |   |                |               |   | o |                 |
|               |   |   |                |               |   | r |                 |
|               |   |   |                |               |   | t |                 |
|               |   |   |                |               |   | t |                 |
|               |   |   |                |               |   | o |                 |
|               |   |   |                |               |   | n |                 |
|               |   |   |                |               |   | s |                 |
|               |   |   |                |               |   | * |                 |
|               |   |   |                |               |   | * |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **VOLUME      |   |   |                | **VOLUME      |   |   |                 |
| (A            |   |   |                | (A            |   |   |                 |
| PPROXIMATE)** |   |   |                | PPROXIMATE)** |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 teaspoon  | * |   | **5            | **1           | * |   | **0.03 fluid    |
| (tsp)**       | * |   | milliliters    | milliliter    | * |   | ounce (fl oz)** |
|               | = |   | (ml)**         | (ml)**        | = |   |                 |
|               | * |   |                |               | * |   |                 |
|               | * |   |                |               | * |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1           | * |   | **15           | **1 liter     | * |   | **2.1 pints     |
| tablespoon    | * |   | milliliters    | (l)**         | * |   | (pt)**          |
| (tbsp)**      | = |   | (ml)**         |               | = |   |                 |
|               | * |   |                |               | * |   |                 |
|               | * |   |                |               | * |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 fluid     | * |   | **30           | **1 liter     | * |   | **1.06 quarts   |
| ounce (fl     | * |   | milliliters    | (l)**         | * |   | (qt)**          |
| oz)**         | = |   | (ml)**         |               | = |   |                 |
|               | * |   |                |               | * |   |                 |
|               | * |   |                |               | * |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 cup (c)** | * |   | **0.24 liter   | **1 liter     | * |   | **0.26 gallon   |
|               | * |   | (l)**          | (l)**         | * |   | (gal)**         |
|               | = |   |                |               | = |   |                 |
|               | * |   |                |               | * |   |                 |
|               | * |   |                |               | * |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 pint      | * |   | **0.47 liter   |               |   |   |                 |
| (pt)**        | * |   | (l)**          |               |   |   |                 |
|               | = |   |                |               |   |   |                 |
|               | * |   |                |               |   |   |                 |
|               | * |   |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 quart     | * |   | **0.96 liter   |               |   |   |                 |
| (qt)**        | * |   | (l)**          |               |   |   |                 |
|               | = |   |                |               |   |   |                 |
|               | * |   |                |               |   |   |                 |
|               | * |   |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 gallon    | * |   | **3.8 liters   |               |   |   |                 |
| (gal)**       | * |   | (l)**          |               |   |   |                 |
|               | = |   |                |               |   |   |                 |
|               | * |   |                |               |   |   |                 |
|               | * |   |                |               |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 cubic     | * |   | **0.03 cubic   | **1 cubic     | * |   | **36 cubic feet |
| foot (cu ft,  | * |   | meter (m^3^)** | meter         | * |   | (cu ft,         |
| ft^3^)**      | = |   |                | (m^3^)**      | = |   | ft^3^)**        |
|               | * |   |                |               | * |   |                 |
|               | * |   |                |               | * |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **1 cubic     | * |   | **0.76 cubic   | **1 cubic     | * |   | **1.3 cubic     |
| yard (cu yd,  | * |   | meter (m^3^)** | meter         | * |   | yards (cu yd,   |
| yd^3^)**      | = |   |                | (m^3^)**      | = |   | yd^3^)**        |
|               | * |   |                |               | * |   |                 |
|               | * |   |                |               | * |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **TEMPERATURE |   |   |                | **TEMPERATURE |   |   |                 |
| (EXACT)**     |   |   |                | (EXACT)**     |   |   |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+
| **\[          | * |   | **y C**        | **\[(9/5) y + | * | * |                 |
| (x-32)(5/9)\] | * |   |                | 32\] C**      | * | * |                 |
| F**           | = |   |                |               | = | x |                 |
|               | * |   |                |               | * | F |                 |
|               | * |   |                |               | * | * |                 |
|               |   |   |                |               |   | * |                 |
+---------------+---+---+----------------+---------------+---+---+-----------------+

![](media/image4.wmf)

![](media/image5.wmf)

For more exact and or other conversion factors, see NIST Miscellaneous
Publication 286, Units of Weights and Measures. Price \$2.50 SD Catalog
No. C13 10286 **Updated 6/17/98**

PREFACE

This report summarizes work performed under an ongoing research program
at the Volpe National Transportation Systems Center, Cambridge,
Massachusetts, in collaboration with the Human-Machine Systems
Laboratory at the Massachusetts Institute of Technology (Cambridge,
Massachusetts). Supported by the Office of Research and Development,
Federal Railroad Administration, the program is part of a comprehensive
effort to identify and develop the technical information required for
safety regulation of high-speed ground transportation. This is a final
report on one component of the overall research program.

As vehicle speed increases, the information processing demands on the
locomotive engineer become more significant. Relevant information is
presented to the sensory systems at a higher rate, thereby reducing the
available latency time for decisions and control actuation. To ensure
that the engineer can adequately control the vehicle, human factors
issues relative to this task must be sufficiently investigated. An
earlier component of this research identified the task requirements of
the locomotive engineers and central traffic control operators (Sheridan
et al., 1994). This work also included review of the operator tasks in
existing high-speed rail systems throughout the world.

More recent efforts focused on locomotive engineer performance and
determined that there are two categories of operator aids most likely to
be implemented in actual vehicles: advanced display-based decision aids,
and advanced supervisory control. In the first case, the engineer is
provided with additional information via advanced display technology,
with the intent of improving the planning and decision capabilities of
the engineer while underway. The second approach provides the engineer
with supervisory control systems that reduce the required decision and
actuation task load.

Simulation experiments have been conducted to explore the effects of
these aids on operator performance. In order to determine the individual
effects of each type of aid, separate experiments were conducted for
each. The results of the experiment that evaluated the decision aids
were reported in (Askey and Sheridan, 1996). This report focuses on the
human factors issues of advanced supervisory control. In particular,
this work addresses the effects of supervisory control on operator
performance.

A companion report describes the theoretical development and
experimental demonstration of the safety state model (Lanzilotta, 1996).
The safety state model is a stochastic model of human-machine system
behavior. The model utilizes a finite discrete Markov process to
estimate the dynamic risk probability as a function of system state. The
model is calibrated using observational data from an operational system.
Application of the model is demonstrated through application to
high-speed rail systems, using data obtained in the experiment described
in this report.

Thus, the supervisory control experiment serves a dual purpose. First,
it is a human behavioral study in the effects of supervisory control on
human operator behavior in high-speed rail systems. Second, the
experiment is a data generator for demonstration of a novel technique
for estimating dynamic risk probability.

# ACKNOWLEDGMENTS {#acknowledgments .WW-Contents-1}

The authors would like to acknowledge and thank the many people who were
involved with and contributed to the completion of this work. In
particular, we would like to thank Dr. Thomas Raslear of the Federal
Railroad Administration for his guidance and support. Dr. Donald Sussman
and Mr. Robert Dorer, at the Volpe National Transportation Systems
Center (Volpe Center), lent significant contributions to the shape and
direction of the work, and were able to provide key contacts and
references. In addition, we would like to thank Dr. Peter Mengert and
Mr. Robert DiSario for graciously sharing their knowledge and experience
in matters of statistical analysis and experiment design. Mr. J. K.
Pollard was instrumental in building the simulator throttle.

At the Massachusetts Institute of Technology, we would like to thank our
colleagues in the Human-Machine Systems Laboratory for their
contributions and support. Through collaborative work in simulation
system development and complementary experimental work, my association
with Ms. Shumei Yin Askey was fruitful and enlightening. Mr. Nicholas
Patrick was especially helpful with statistical analysis and
interpretation. Messrs. Jacob Einhorn, Bernardo Aumond, Steven
Villareal, and Helias Marinakos have all been of assistance while in the
process of taking on the next phases of the project. Our undergraduate
assistants, Ms. Sapna Augustine, Ms. Wendy Chang, Ms. Grace Park, Mr.
Joseph Wenish, and Ms. Jill Chen, were helpful in preparing for and
conducting the experimental portion of the research. Dr. Jie Ren built
the analog-to-digital converter used with the simulator throttle.

We would also like to acknowledge Messrs. John Tolman, George Newman,
and Walter Nutter, of the Brotherhood of Locomotive Engineers, for their
input during focus group discussions. Mr. Dennis Coffey and the
Massachusetts Department of Transportation and Mr. Jack Flaherty of the
Massachusetts Bay Transportation Authority were instrumental in
arranging head-end rides, which provided valuable hands-on experience
for the authors. Mr. Stephen Jones organized a visit to the Amtrak
Centralized Traffic and Electrification Control facility.

Finally, special thanks to Dr. Judith Bürki-Cohen, of the Volpe Center,
for her guidance and enthusiasm throughout this work. Her experience in
experimental research was invaluable throughout the project, and was,
along with her editorial input, critical to the successful completion of
the experiments and subsequent reports.

# TABLE OF CONTENTS {#table-of-contents .WW-Contents-1}

**[Section]{.underline}** **[Page]{.underline}**

[EXECUTIVE SUMMARY ix](#executive-summary)

[1. INTRODUCTION 1](#introduction)

[2. METHOD 7](#method)

[2.1 High-Speed Rail Simulation System
7](#high-speed-rail-simulation-system)

[2.2 Experiment Design 10](#experiment-design)

[2.3 Subjects 14](#subjects)

[2.4 Procedures 14](#procedures)

[3. RESULTS 17](#results)

[3.1 Response Time to Unexpected Failures
17](#response-time-to-unexpected-failures)

[3.2 Response Accuracy 21](#response-accuracy)

[3.3 Subjective Evaluation 23](#subjective-evaluation)

[4. DISCUSSION AND INTERPRETATION 25](#discussion-and-interpretation)

[5. CONCLUSIONS AND RECOMMENDATIONS
27](#conclusions-and-recommendations)

[APPENDIX A. TRAINING TUTORIAL 31](#appendix-a.-training-tutorial)

[APPENDIX B. WRITTEN REVIEW QUIZ 57](#appendix-b.-written-review-quiz)

[APPENDIX C. TRAIN SCHEDULE 65](#appendix-c.-train-schedule)

[APPENDIX D. EXIT QUESTIONNAIRE 67](#appendix-d.-exit-questionnaire)

[APPENDIX E. INTERACTIVE TRAINING PROCEDURE
69](#appendix-e.-interactive-training-procedure)

[REFERENCES 71](#references)

# LIST OF FIGURES {#list-of-figures .WW-Contents-1}

**[Figure]{.underline} [Page]{.underline}**

[1. Closed-Loop Vehicle Control 2](#__RefHeading___Toc84667730)

[2. Simulation System Configuration 7](#__RefHeading___Toc84667731)

[3. Box-Plot Display of Brake Failure Response Time
19](#__RefHeading___Toc84667732)

[4. Box-Plot Display of Motor Failure Response Time
19](#__RefHeading___Toc84667733)

[5. Box-Plot Display of Obstruction Failure Response Time
20](#__RefHeading___Toc84667734)

[A-1. Track Layout, Simulated Rail System
32](#__RefHeading___Toc84667735)

[A-2. Block Signaling System 34](#__RefHeading___Toc84667736)

[A-3. Instrument Panel Layout 35](#__RefHeading___Toc84667737)

[A-4. Full-Throttle Acceleration Profile
46](#__RefHeading___Toc84667738)

[A-5. Full-Service Braking Profile 47](#__RefHeading___Toc84667739)

[A-6. Emergency Braking Profile 48](#__RefHeading___Toc84667740)

[A-7. Bonus Point Diagram for Station Stopping Accuracy
53](#__RefHeading___Toc84667741)

# LIST OF TABLES {#list-of-tables .WW-Contents-1}

**[Table]{.underline} [Page]{.underline}**

[Table 1. Subject Counterbalancing 12](#__RefHeading___Toc90287949)

[Table 2. Failure Scenarios 13](#__RefHeading___Toc90287950)

[Table 3. Response Time Data for Brake Failure
18](#__RefHeading___Toc90287951)

[Table 4. Response Time Data for Motor Failure
18](#__RefHeading___Toc90287952)

[Table 5. Response Time Data for Obstruction Failure
18](#__RefHeading___Toc90287953)

[Table 6. Results of Bartlett's Test 21](#__RefHeading___Toc90287954)

[Table 7. Summary of Brake Failure Response Accuracy
22](#__RefHeading___Toc90287955)

[Table 8. Summary of Motor Failure Response Accuracy
22](#__RefHeading___Toc90287956)

[Table 9. Summary of Obstruction Failure Response Accuracy
22](#__RefHeading___Toc90287957)

[Table 10. Computed X2 Values for Response Accuracy
23](#__RefHeading___Toc90287958)

[Table 11. Subjective Situation Awareness Evaluation and Preference
24](#__RefHeading___Toc90287959)

[Table A-1. Rail Signal Codes 34](#__RefHeading___Toc90287960)

[Table A-2. Relationship Between Vehicle Position and Out-the-Window
View 38](#__RefHeading___Toc90287961)

[Table A-3. Summary of Low-Speed Braking Distances
39](#__RefHeading___Toc90287962)

[Table A-4. Standard Communications Message Initiated by Vehicle
Operator 50](#__RefHeading___Toc90287963)

[Table A-5. Standard Communications Messages Initiated by CTC Operator
50](#__RefHeading___Toc90287964)

[Table A-6. Bonus Point Schedule for Station Stopping Accuracy
53](#__RefHeading___Toc90287965)

[Table A-7. Bonus Point Schedule for Schedule Accuracy
54](#__RefHeading___Toc90287966)

[Table A-8. Bonus/Penalty Point Schedule for Emergency Response
54](#__RefHeading___Toc90287967)

[Table A-9. Penalty Point Schedule for Violations
55](#__RefHeading___Toc90287968)

[Table A-10. Penalty Point Schedule for Grade Crossing Collisions
56](#__RefHeading___Toc90287969)

#   {#section .unnumbered}

# EXECUTIVE SUMMARY

This report describes the motivation, background, and results of a set
of experiments that evaluated the effects of supervisory control on the
performance of locomotive engineers in high-speed train operations.

Control automation specifically refers to automatic devices designed to
perform the fundamental tasks of vehicle control. These tasks include
speed regulation (between stations) and position control (within
stations). Three types of automatic control systems were considered:
cruise control, programmed stop, and autopilot. A cruise control system
maintains a constant speed, which is set by the engineer. A programmed
stop system stops the vehicle at a precise location within the
station---the engineer merely invokes the system under a set of
prescribed circumstances to achieve accurate stopping performance. An
autopilot system regulates the vehicle speed such that it follows a
pre-programmed speed trajectory (as a function of vehicle position), and
meets a set of pre-programmed stopping points. Once the vehicle is in
motion and under autopilot control, no further input is required for
standard operation.

As the level of supervisory control increases, the effect automation has
on human operator performance when called upon to respond to emergency
situations is unknown. Under fully manual operation, the engineer is
responsible for speed regulation, position control, and system
monitoring. In general rail vehicle operation, these tasks do not seem
to present notably high mental workload levels. Increasing the level of
supervisory control further lessens the engineer's workload. The result
could lead to locomotive engineer performance improvement relative to
system monitoring, due to greater availability of mental resources. On
the other hand, the reduction in workload could result in a higher level
of complacency or boredom, ultimately leading to a decrease in
performance of the locomotive engineer relative to the system monitoring
task.

Experimental work to explore this question was conducted using a
laboratory-based simulation system. Twelve subjects drawn from the
general student population were tested. Each subject had to undergo a
6-hour training course, to familiarize each of them with the locomotive
engineers tasks. Each test subject then participated in a total of 9
hours of experimental tests, consisting of three individual 3-hour
sessions. Each subject was given three variations of automation level:
fully manual control, partial automation (cruise control and programmed
stop), and full automation (autopilot). Each subject was exposed to the
three treatments across three test sessions; each test session utilized
only one treatment. The dependent variable was response to "unexpected"
emergencies. Three emergencies were used: brake failure, traction motor
failure, and grade crossing obstruction. All emergencies were
recoverable (i.e., the test did not end upon the occurrence of an
emergency). The responses to the emergencies were measured for both
response time and response accuracy.

The results showed that there was a significant difference in the
variance of response times to the brake failures and traction motor
failures for the partial automation treatment when compared with the
manual and full automation treatments. This suggests that, when using
cruise control, the engineers had more of a tendency to bias their
visual attention toward monitoring the external environment and away
from the instrument panel. There was no significant difference found
between the treatments (for either the mean response time or the
response time variance) in the case of grade crossing obstruction. There
was no significant difference in the response accuracy in any of the
test comparisons.

The experimental results suggest that the use of cruise control reduces
attention relative to failure detection indicated on the instrument
panel. However, the experimental results also revealed that none of the
treatments had an adverse effect on attention with respect to grade
crossing obstructions. This finding is significant because, in general,
grade crossings represent a significant risk in rail operations. No
conclusions could be drawn with regard to response accuracy. The number
of data points available from this experiment was not large enough to
provide a statistically significant sample of data for such a
comparison. In reviewing responses to a subjective rating questionnaire,
it was concluded that the engineers believed full automation resulted in
the lowest level of awareness, while the manual control treatment
provided the highest level of awareness.

# 1. INTRODUCTION

As the United States moves toward high-speed passenger rail service,
questions emerge regarding the usefulness and implications of vehicle
automation. Study of existing foreign high-speed passenger rail
operations, Train à Grande Vitesse (TGV) in France, Inter-City Express
(ICE) in Germany, and Shinkansen in Japan, shows that implementing
automation in these systems differ in degree and philosophy. In
particular, the ICE embraces a high degree of automation; the TGV system
provides the engineer with more advanced electronic assistance while
retaining a high human interaction level for vehicle control (Bing,
1990).

Incorporating automation in rail vehicles simplifies the task of train
operation while gaining greater consistency in overall system
performance. The primary task in rail vehicle operation is speed
control. Automating the speed control task will allow the engineer to
focus on higher-level tasks, including monitoring for vehicle failures
and other emergencies. The implication is increased use of automation
will improve the overall performance of the locomotive engineer and the
system.

The goal of this research is to gain a better understanding of the
implications of supervisory control on human operator performance. Any
automatic system will necessarily be designed to a set of performance
criteria, and a successful implementation will meet those criteria.
However, in introducing automation into the human machine system, the
automatic systems change the nature of the interaction between the human
and the machine. While in manual control, the engineer interacts
directly with the vehicle; with supervisory control, the task of the
locomotive engineer becomes a monitoring task, leading to a more
indirect role of the engineer in vehicle control. Automation has
potential implications in the areas of system safety and overall system
performance; in addition, there are issues relative to task loading,
complacency, and training of locomotive engineers.

Concerns identified include the effects of differing levels of
supervisory control on human operator monitoring and intervention
performance, as well as related effects on overall system performance.
If introducing automation results in perfect "operator performance" as
it is traditionally measured (for example, station-stopping performance
or schedule maintenance) but degrades the overall system performance
(for example, with regard to safety), this is a negative overall system
impact.

System performance with respect to safety is of particular concern.
Logically, perfect operator performance should result in perfect system
performance with regard to safety, provided the operator performance is
appropriately defined and measured. However, vehicle automation systems
are designed to improve the traditional measures of operator
performance, such as station stopping and schedule keeping. In the
absence of an appropriate measure of operator performance relative to
safety, it is possible that an automation system could improve the
operator performance according to the traditional measures while
adversely affecting overall system safety.

Early in this work, vehicle automation was divided into two broad
categories. If you imagine the locomotive engineer as a component of a
closed-loop control system (Figure 1), you will observe a
*perception*-*decision-actuation* paradigm---the engineer perceives the
state of the vehicle and environment, decides on a course of action, and
takes action through the available vehicle controls (actuators).
Typically, the engineer learned the operating rules through formal
training. The perceived state of the vehicle and environment is compared
to the allowed states governed by the operating rules, and any perceived
differences are cause for a decision process, culminating in a plan of
action modifying the vehicle state.

![](media/image6.wmf)

[]{#__RefHeading___Toc84667730 .anchor}Figure 1. Closed-Loop Vehicle
Control

Two of the most significant subtasks performed by the engineer are data
gathering (perception) and control command (decision). Data gathering is
the process of observing and interpreting available vehicle and system
state information. State information may be obtained from in-vehicle
instruments or displays, or it may be observed on wayside signals or
signs. The data gathering generally occurs through the visual and aural
information channels. Control command is the process of using the
observed and interpreted data in conjunction with the operating rules
and regulations, to make a control decision and perform the actuation
required to implement that control decision. The control command process
generally involves physical interaction between the engineer and the
vehicle, typically through throttle and brake levers and control
buttons.

Data gathering and control command together form the basis of
operator-based closed-loop speed and position control. Speed control
involves regulating the vehicle speed such that the vehicle complies
with schedule and speed limit constraints. These two constraints run
counter to one other. Tighter schedules imply higher speeds, while speed
limits restrict the vehicle speed in the interest of safety. An optimum
schedule minimizes the travel time without requiring speed in excess of
known fixed speed limits. Position control involves stopping the vehicle
at prescribed stop points, typically at stations or terminals. The
significance of data gathering and control command subtasks is supported
by a task analysis of the locomotive engineer, as performed in the early
part of this research (Sheridan et al., 1994).

Based on this task division, automation in the cab can be separated into
display automation and supervisory control. Display automation modifies
the data gathering process, while supervisory control modifies the
control command process. With increased levels of display automation,
the information presented to the locomotive engineer includes higher
levels of processing that otherwise might be performed internally by the
engineer. For example, adding a preview display provides advance
information about the track ahead, even if this portion of the track is
out of visible range. A predictor display provides advance information
on the vehicle state trajectory, based on the current vehicle and
control states. An advisor display provides a suggested vehicle state
trajectory, optimized for various constraints. The combination of these
three systems provides the locomotive engineer with a powerful set of
tools for improving performance.

The human performance concern, with regard to display automation, is
potential overload of the operator sensory channels. Too much
information will ultimately degrade overall performance due to the
inability to process that information and extract the pertinent data
from it. Experimental research in this area is part of the overall
research project task reported in Askey and Sheridan (1996) and
Askey (1995).

With supervisory control, an automatic system assumes the control of
vehicle speed and position. The three types of supervisory control
expected in high-speed rail systems are cruise control, programmed stop,
and autopilot. A cruise control system is designed to maintain a
constant speed set by the locomotive engineer, functionality similar to
automobile cruise control systems. This frees the engineer from
regulating vehicle speed in normal operational scenarios. However, the
engineer still must monitor the wayside (for observation of speed limit
indicators, such as signals and block markers) and vehicle systems (for
observation of cruise control status, such as set speed), and the
engineer must be ready to take control of the vehicle if the situation
warrants. A programmed stop system will stop the vehicle at a
pre-specified position, typically at a station. An autopilot is similar
to cruise control, except that the desired speed is pre-programmed as a
function of vehicle position. In addition, an autopilot incorporates the
programmed stop for automatic station stopping.

The human performance concern, with respect to supervisory control, is
that the engineer's situation awareness may be reduced as automation
systems assume more of the control task. This reduction in situation
awareness, characterized as an "out-of-the-loop" situation, is where the
engineer is no longer actively involved with the immediate task. The
implication is that in the event of an emergency or fault situation, the
operator may consume precious response time trying to gain a perspective
on the system state that might require the engineer to take control of
the vehicle from the automation system, resulting in a delayed response.
In addition, the engineer may respond in an inappropriate manner as a
result of being "out-of-the-loop." Thus, the "operator out-of-the-loop"
situation poses serious safety implications.

The goal of this work is to investigate the relationship between
supervisory control and performance of the locomotive engineer in
high-speed rail vehicles. Of particular interest are the effects of
supervisory control on operator attentiveness and situation awareness.
Much situation awareness work comes from the perspective of aircraft
control. Characteristics of aircraft include rapid motion, highly
dynamic scenario evolution, and the potential for grave consequences in
the event of an accident, characteristics especially suitable for the
study of situation awareness. With increasing levels of supervisory
control and display aids in aircraft cockpits, there is heightened
concern that the operator will lose perspective and awareness of the
vehicle and environment states, and thus compromise the ability to
operate the vehicle.

As rail vehicles move into high-speed operation, with speeds approaching
or exceeding 186 mph (300 km/h), the concerns become similar to those of
aircraft. High speed and momentum carry the risk of grave consequences
in the event of a collision. In addition, the related high rate of
ground coverage, along with increasing levels of automation and other
forms of operator aids, increase the risk of operator error and
resultant accident. This is of concern especially when automation
transforms the task of the locomotive engineer from actuator control to
instrument monitoring, thus lowering the level of direct interaction.

In the human factors research literature, the concept, definition, and
measurement of situation awareness remains a topic of debate (Endsley,
1987; Endsley, 1988; Endsley, 1995; Gaba, et al., 1995; Hendy, 1995;
Smith and Hancock, 1995; Sarter and Woods, 1995). For the purpose of
this research, situation awareness was considered to be a useful
qualitative concept for discussing the effects of automation. The
overall notion that situation awareness includes the adaptive coupling
between humans and machines is of central importance. However, many of
the techniques currently available for evaluating situation awareness
incur some level of intrusiveness into the operational scenario. The
experiment described herein uses emergency response measurement in an
effort to avoid the problem of task intrusion.

Attention allocation is a research area related to situation awareness.
Operator attention is a limited resource which is dynamically allocated.
There are three categories of attention allocation: selective attention,
focused attention, and divided attention (Sanders and McCormick, 1987;
Wickens, 1992). With *selective attention*, an operator monitors several
sources of information, looking for the occurrence of particular events.
The *load stress* increases with an increasing number of channels of
information, while the *speed stress* increases by increasing the
information rate. According to work by Goldstein and Dorfman (1978),
load stress is more likely to degrade performance than speed stress.
*Focused attention* occurs when an operator attempts to monitor a few
information sources, often in the presence of distracting noise. The
noise is considered information on other channels---focused attention is
the process of "tuning out" the less important information in favor of
the more critical information. If competing information occurs in the
visual mode, spatial proximity of the two sources of information can
degrade focused attention. *Divided attention*, also termed
*timesharing*, occurs when an operator must perform more than one task
at a given time. Divided attention differs from selective attention in
that the operator is actively performing useful work while monitoring
information sources; with selective attention, the primary task is
information monitoring. There is general agreement that there is limited
human capacity for divided attention, although cognitive psychologists
have a variety of theories for describing the mechanisms involved
(Senders, 1964; Wickens, 1994; Sanders and McCormick, 1987). Despite the
theories and classifications of attention allocation, much remains
unknown. Sanders and McCormick (1987) succinctly state: "Even with all
the theory building and research in the area of divided attention, there
is still much we do not understand. How these factors come together to
influence performance is still not entirely clear. Predictions on the
outcome of timesharing real-world tasks, therefore, are still relatively
primitive."

Regardless of the theoretical models, a practical issue relative to
operation of high-speed rail vehicles remains: How does the transition
to higher speeds affect the ability of a locomotive engineer to obtain,
interpret, and act on information pertinent to vehicle operation? When
engineers monitor one or more displays, they should view (sample) each
display frequently enough and for sufficient duration to extract the
information presented. Typically, the monitoring field of the engineer
is distributed across two broad areas of potential visual focus: the
instrument panel (located within the cab, also known as the dashboard),
and the environment outside the cab. The focal distances of the two
focus areas differ enough that it is generally difficult for an engineer
to have concurrent visual focus on both. As a result, the engineer must
alternate his visual attention between the instrument panel and the
external environment. The instruments on the dashboard are considered to
be displays in the typical human factors sense; we can also consider the
external view to be a "display," as it could be implemented with a
camera and monitor screen in place of a traditional window.

Operating a rail vehicle (and, in general, operating any vehicle) can be
considered a combination of divided attention and selective attention
tasks. The task is divided attention, in that the locomotive engineer
must attend to several different tasks at once, including speed control,
position control, system status monitoring, and vehicle status
monitoring. The monitoring subtasks can each be considered as selective
attention tasks. The objective is to identify a system or vehicle fault,
and the engineer must monitor several channels of information to detect
a fault. From a different perspective, the task of a locomotive engineer
is a combination of relatively high frequency monitoring and control (to
fulfill the task of speed and position control) with vigilance (for
system failures and emergencies).

Attention bias is the degree to which the operator's attention is
allocated within an attention classification scheme. For rail vehicle
operation, allocation of attention is discussed in several areas:
separate visual focus areas (in-cab instrument versus external
environment), separate types of attention allocation (divided attention
versus selective attention), and different levels of information
bandwidth (monitoring versus vigilance).

Introducing supervisory control at high speed has the potential for
significantly altering the role of the locomotive engineer. Potential
effects include degrading situation awareness and attention allocation,
as well as increasing fatigue, complacency, and boredom. The
experimental work described in this report determined the extent of the
impact on human performance by incorporating supervisory control in
high-speed rail. Subjects were asked to operate a passenger train in a
high-speed rail simulation system, according to a set of operating rules
and schedule. The subjects performed three separate test runs, each with
a different level of supervisory control. During the test runs, the
subjects were exposed to various emergency situations requiring active
response. Response times and response accuracy to these emergencies were
measured and compared. The hypothesis is that increasing the level of
supervisory control will have a significant effect on the attention bias
of the engineer, and the overall effect of supervisory control on
engineer response will depend on the significance level of the
emergency.

# 2. METHOD

## 2.1 High-Speed Rail Simulation System

The High-Speed Rail Simulation System was used to conduct the
experiment. This system is a human-in-the-loop simulator designed for
use in human factors experiments. Through a modular design philosophy,
this system can be reconfigured for a variety of experimental needs. The
following sections describe the configuration used for the supervisory
control experiment. For a more detailed description of the design and
implementation of the high-speed rail simulation, see Appendix A of
Lanzilotta, 1996.

### **2.1.1 System Configuration**

The simulation system operated on a set of Silicon Graphics graphics
workstations, which communicated via a local area network. The system
used C programming language and ran under the Irix operating system. For
the experiment described in this report, the system configuration
utilized three workstations (Figure 2) manufactured by Silicon Graphics,
Inc. (SGI). The workstations included one Indigo-2 model and two
Personal Iris machines.

![](media/image7.wmf)

> []{#__RefHeading___Toc84667731 .anchor}Figure 2. Simulation System
> Configuration

One Personal Iris was configured as the Central Traffic Control (CTC)
operator interface. The experimenter operated this machine. The CTC
operator (also called the dispatcher) normally monitors the overall
state of the system, controlling the state of the switches, and acts as
supervisor for the vehicles in the system. The primary display at this
interface was a plan-view map of the rail system. Figure 2 depicts this
workstation on the left, and describes its function (CTC) and display
features.

The train simulation required the use of two workstations. One
workstation, an Indigo-2 (with Extreme graphics), provided the
out-the-window (OTW) display. The software used to create the OTW view
operated in conjunction with the vehicle dynamics computations. The
other workstation, a Personal Iris, was configured as the instrument
panel (dashboard) display. The subjects acted as locomotive engineers,
applying input via a control lever (used for the combined functionality
of thrust and brake commands) and keyboard inputs. Figure 2 shows these
two workstations on the right. The rectangular box around the two
workstation icons shows that they have related functionality (vehicle
simulation), while the individual icons identify the type of machine and
display functions of each workstation.

The train cab environment in the simulation system consisted of two
workstations on a large computer table. Mounted on the right-hand side
of the table was a full-size throttle lever (adapted from a conventional
boat throttle). The table was in an isolated room; partitions enclosed
the test subject. The CTC operator environment consisted of a computer
table and a single workstation.

### **2.1.2 Subject Interface**

In addition to the two computer displays, computer keyboard, and control
lever on the computer table, additional information was available to the
test subjects on paper. This information could be used at their
discretion, and included a map of the rail system, a summary of the
operating schedule, and a summary of the rail signal codes.

The display on the left had a dedicated OTW view. The OTW view as
designed is a night view of the environment, with objects lighted by the
vehicle (e.g., a headlight). The rails and roadbed were drawn as fading
into the distance. The roadbed included simple rock-like objects to
provide a sense of motion, especially at lower vehicle speeds. In
addition, the view of the rails was designed to vibrate with vehicle
motion, with increasing amplitude at higher speeds, heightening the
perception of speed.

Static objects in the environment appeared as wire-frame images. There
were several types and sizes of objects, and simple object shapes
combined to create more complex structures. Mileposts appeared as
reflective black-on-white signs on the right side of the road, and block
signals appeared overhead, with "light-emitting" signals and reflective
identification numerals above. Grade crossings appeared as gray
roadways, and the highway vehicles appeared as solid blue cars. Stations
appeared as wire frame shapes, with purple and blue walls. When the
front edge of the vehicle was within the boundaries of the station, a
head-up display appeared on the windscreen, for the engineer to use as
an aid for vehicle positioning in the station.[^1]

The display on the right showed the vehicle's instrument panel,
containing the gauges, displays, and warning lights available to the
engineer (Figure A-3 on page 39). In the center of this display was a
large round speedometer dial gauge. This gauge was calibrated to 217.5
mph (350 km/h), and had a red pointer to indicate current speed. A
yellow pointer, located beneath the red pointer, indicated the
controlled speed when the vehicle was operating in one of the automation
modes (cruise control, programmed stop, or autopilot). Four smaller
round gauges displayed system values, including brake tank pressure (two
gauges), wheel bearing temperature, and power supply voltage. Three
color-coded indicator lights showed automation mode engagement. Four
vertical LED-bar indicators indicated the current level applied to the
four traction motors. Four color-coded indicator lights showed other
vehicle warnings and status, including ATP system warning/penalty,
emergency brake activation, alerter system warning/penalty, and door
status. In-cab signaling provided for both the currently occupied block
and the next approaching block. A text display was used for the
communication channel. A digital system clock was provided.

The primary input device was a combination control lever. Built from a
modified boat throttle and mounted into the computer table, the subject
used this control to issue thrust and brake commands to the vehicle. The
full forward position (i.e., away from the engineer), applied maximum
thrust to the vehicle. Conversely, in the full backward position,
maximum braking was applied. A detent in the center of travel was used
for coasting. The control lever was connected to a potentiometer, which
controlled a voltage converted by an analog-to-digital (A/D) converter
into a digital number. The digital form of the control command was sent,
via a serial link, to the workstation for use in the vehicle dynamics
software.

All other engineer input was performed through the computer keyboard.
The top row of function keys acted as control buttons for a variety of
vehicle functions, including alerter response, automation mode enable,
motor circuit breaker reset, brake system reset, door control, manual
control of emergency braking, and emergency brake reset. The "arrow"
keys ("up-arrow" and "down-arrow") controlled the set speed in cruise
control mode. In addition, the alphanumeric keys were used to type
messages in the communications channel.

### **2.1.3 Design and Implementation of Control Automation Systems**

Included in the train simulation were three supervisory control systems:
cruise control, programmed stop, and autopilot.

The cruise-control system was designed to maintain a constant,
operator-selected speed. The system was engaged by depressing the
appropriate control button, which maintained the current vehicle speed.
The set speed was modulated via the up-down arrow keys on the keyboard.
The controller was implemented as a proportional-integral (PI)
controller that regulates speed, using thrust only. Manual application
of service brakes disengaged the cruise control system.

The programmed stop system was designed to stop the vehicle at the end
of the current block. It was, in effect, a closed-loop position control
system. Depressing the appropriate control button engaged the system. If
engaged properly, the system stopped the vehicle using a brake curve
lookup table to determine braking force. Several safeguards protected
against improper usage: 1) the engagement speed must be below 49.7 mph
(80 km/h), and 2) the distance to the stop point must exceed the minimum
required braking distance. Violating either of these conditions caused
the emergency brakes to be applied. During normal operation of the
programmed stop system, manually applying the service brakes disengaged
the programmed stop system.

The autopilot was a speed regulation system, similar to the
cruise-control system. Depressing the appropriate control button engaged
the system. The set speed was pre-programmed as a speed trajectory
function of vehicle position. The controller was implemented as a PI
controller for thrust and brakes, in conjunction with the programmed
stop system in the vicinity of stations. Manually applying the service
brakes disengaged the autopilot system.

## 2.2 Experiment Design

### **2.2.1 Subject Task**

At the highest level, the task was to control a simulated rail vehicle
through a virtual rail system. The objective was to involve the subject
to the highest degree possible, in the task of a locomotive engineer.
This overall task has two components---vehicle control and system
monitoring. Vehicle control includes active participation on the part of
the human, by manipulating control levers and switches; system
monitoring is entirely passive.

Vehicle control consists of speed and position control of the vehicle.
Vehicle speed is regulated through monitoring of speed and active
response using the throttle and brake, to meet conflicting constraints
of schedule requirements and speed limits. Position control occurs when
stopping the vehicle at stations and terminals. The level of vehicle
control varied for the subject as the level of supervisory control was
varied in the experiment.

System monitoring included monitoring the vehicle systems. With respect
to the vehicle systems, the subject monitored for brake and motor
failures specifically, and system anomalies in general. The subject
monitored the environment in which the train was passing, including
observing passing mileposts (for position identification), block signals
(for both position identification and signal observance), wayside
landmarks (to identify braking points), and grade crossing status (to
identify obstructions in the crossings). In addition, the subject
monitored the vehicle speed and the in-cab signals at all times to
determine whether current vehicle speed complied with applicable speed
limits, regardless of the level of supervisory control in use.

The rail system used was a two-station shuttle system, separated by 31.1
mi (50 km) of track. Outside each station a looping section of track
(with a switch) reversed the vehicle on the main track (see Figure A-1
on page 36). The one-way travel time between the two stations was
approximately 18 minutes, and the travel time around the loop
approximately 7 minutes. In each test session, the subject operated the
vehicle on three roundtrip circuits of the system. Each test session
required approximately 3 hours.

The subject controlled the speed (and consequently, the position) of the
vehicle by applying either thrust or braking forces, through the
combined control lever. The selected speed was subject to speed limit
constraints that were due to either civil speed limits (static) or
signal speed limits (dynamic). The selected speed was also subject to
the prescribed schedule, implying that a minimum average speed be
maintained over each trip leg.

### **2.2.2 Independent Variable**

The independent variable for this experiment was the level of
supervisory control. Three levels of automation were used: no automation
(manual control only), partial automation (use of both cruise control
and programmed stop), and full automation (autopilot).

Under manual control, the subject was required to perform all vehicle
operation tasks, including monitoring vehicle speed, vehicle position,
block signal states, determining block speed limits, and actuation of
throttle and brake controls to vary vehicle speed. When using cruise
control and programmed stop, the requirement for modulating the throttle
and brake controls was removed, implicitly relaxing the requirement for
monitoring the instantaneous vehicle speed. However, monitoring vehicle
position, monitoring signal states, and selection of a desired speed
were required tasks. In the case of autopilot operation, all normal
speed regulation tasks were removed from the responsibility of the
locomotive engineer, who was required to monitor only for and respond to
emergency situations.

### **2.2.3 Dependent Variables**

The primary dependent measure was response to unexpected failures. Two
types of response measures were made at each failure point. One was the
response time, which was measured from the onset of the failure to the
proper action taken in response to that failure. The response time could
vary as a result of perception, decision, or action latencies, or any
combination of the three. The second measure was a rating of the
accuracy or correctness of the response. This measure is, by nature,
more qualitative than the response time measure.

### **2.2.4 Subject Counterbalancing**

To counterbalance possible learning effects, the presentation order of
the automation level was counterbalanced among each group of six
subjects. That is, each subject within a group of six experienced the
three automation modes in a different order. The resultant design
appears in Table 1.

Table 1 identifies the counterbalancing design for a within-subject,
three-treatment experiment. Such an experiment has six different
variants of treatment presentation order. As a result, six subjects
formed a counterbalance group. Each subject test session is known as a
*shift*, and the *shift number* represents the relative shift count for
each individual subject. For example, Subject 1 was asked to use manual
mode for the entire first shift, partial automation for Shift 2,
followed by full automation in Shift 3.

The fourth column of Table 1 presents the failure scenarios. Each
failure scenario represents a set of failures that occurred in a
prescribed order at prescribed positions along the route. The failure
scenarios were designed such that occurrence of failure events would be
perceived to be random. The occurrences of failure types in the set of
scenarios were distributed to reinforce the perception of randomness.
The failure scenarios were not counterbalanced with respect to shift
position. As a result, the failure scenarios are counterbalanced with
respect to automation type. Two different sets of failure scenarios were
utilized, dividing the 12 subjects into 2 groups of 6.

### **2.2.5 Failure Scenarios**

Three different types of failure modes were possible during the test
sessions: brake failure, motor failure, and grade crossing obstruction.
Each represented a different type of detection-response paradigm. Two of
the failure modes can be considered system failures, while the third is
considered an environment failure.

The brake failure was the simplest type of failure. One of the brake
reservoirs lost pressure, which was detected by a slowly dropping
pressure on the brake reservoir pressure gauge. Switching to an
alternate compressor (via a manually controlled switch on the control
panel) rectified the fault. This failure had the simplest
detection-response pattern---the detection was direct, via instrument
panel gauges, and the response required one step. This is a vehicle
system failure.

A motor failure was the other vehicle-based failure. In this scenario,
the circuit breaker "tripped" for one motor (i.e., the circuit was
broken, interrupting power to the motor). The circuit breaker had to be
reset to restore motor operation. The failure was detected by a zero
current reading on one of the motor ammeters located on the instrument
panel. The response consisted of two steps: power to the motors had to
be removed, and the appropriate circuit breaker reset switch had to be
depressed. If the circuit breaker reset button was depressed before
power was removed, all of the other circuit breakers would trip,
necessitating reset of all the motors.

  -------------------------------- --------------- -------------------- --------------------
  []{#__RefHeading___Toc90287949                                        
  .anchor}Table 1. Subject                                              
  Counterbalancing                                                      

  Subject Number                   Shift Number    Automation Type      Failure Scenario

                                   1               m                    a

  1                                2               p                    b

                                   3               f                    c

                                   1               m                    a

  2                                2               f                    b

                                   3               p                    c

                                   1               p                    a

  3                                2               m                    b

                                   3               f                    c

                                   1               p                    a

  4                                2               f                    b

                                   3               m                    c

                                   1               f                    a

  5                                2               m                    b

                                   3               p                    c

                                   1               f                    a

  6                                2               p                    b

                                   3               m                    c
  -------------------------------- --------------- -------------------- --------------------

A grade crossing obstruction was the third failure. In this case, a car
crossing the track became stuck while still partly in the crossing. The
engineer had to identify that the car was stuck, and apply the brakes so
that the train did not collide with the car. Depending on the speed of
the train and the point at which the obstruction was detected the proper
response could be either full service braking or emergency braking.
Thus, this failure required a three-step detection-decision-action
sequence: first, identifying the obstruction; then determining the
proper braking strategy; then enacting the braking strategy. This
failure was considered an environment failure.

The grade crossing failure also differed from the other two failures in
that a strategy decision was required. The engineer determined the
proximity of the danger, and chose a braking strategy based on an
estimation of the danger status. In the other two failure scenarios,
reacting to the failure was always the same; the engineer was only
required to detect the failure and then correctly enact one possible
course of action.

In the course of three test sessions, each subject experienced a total
of six occurrences of each failure type. An important design goal was
maintenance of the perception, from the perspective of the subjects,
that the failures were generated randomly. This goal was subject to the
constraint that the failures actually occur in fixed positions on the
track, in order to maintain experimental control.

To meet these criteria, six track positions were designated for each
failure type. The total number of failures in each test session would be
four, six, or eight, as a function of the test number. Each
counterbalanced group of six subjects (Section 2.2.4) received the same
presentation of failures, with respect to relative test number. However,
because of the counterbalancing design, the distribution of failure
scenarios with respect to automation mode was also counterbalanced with
respect to automation level. See Table 2 for the distribution of failure
scenarios used in the experiment.

The notation used in the table is as follows: Each subject group
consisted of a set of six subjects, with the order of automation
counterbalanced as specified in Table 2. The individual failures are
notated with the letter codes "o" for obstruction, "b" for brake
failure, and "m" for motor failure. The numeral next to the letter code
specifies the position on the track for the failure. For each round trip
(consisting of two consecutive trip legs), six failure points were
specified for each type of failure. Thus, the numeral corresponds to the
relative position of the failure for that failure type. The failure
points were specified such that the different failure types occurred at
different points, precluding a combination failure.

+-----------+-------+---------------+---------------+---------------+
| []{       |       |               |               |               |
| #__RefHea |       |               |               |               |
| ding___To |       |               |               |               |
| c90287950 |       |               |               |               |
| .anc      |       |               |               |               |
| hor}Table |       |               |               |               |
| 2.        |       |               |               |               |
| Failure   |       |               |               |               |
| Scenarios |       |               |               |               |
+-----------+-------+---------------+---------------+---------------+
| Subject   | Shift | 1,2           | Trip Leg      | 5,6           |
| Group     |       |               |               |               |
|           |       |               | 3,4           |               |
+-----------+-------+---------------+---------------+---------------+
|           | 1     | m2,b4         | b3,m4,o4      | o3,b5,m6      |
+-----------+-------+---------------+---------------+---------------+
| A         | 2     | O5,b6         | b2,o6         | o2,m5         |
+-----------+-------+---------------+---------------+---------------+
|           | 3     | b1            | m1            | o1,m3         |
+-----------+-------+---------------+---------------+---------------+
|           | 1     | b2,o3         | b4            | m3            |
+-----------+-------+---------------+---------------+---------------+
| B         | 2     | m1,o1,b6      | m4,o4,b5      | b1,m2         |
+-----------+-------+---------------+---------------+---------------+
|           | 3     | o2,b3         | m6,o6         | o5,m5         |
+-----------+-------+---------------+---------------+---------------+

### **2.2.6 Performance Monitoring and Incentives**

To ensure that proficiency of the test subject, relative to the tasks of
a locomotive engineer, would not affect the test results (i.e., to
assure that the test subjects were capable of adequately controlling the
train), the performance of each test subject was monitored throughout
the test sessions. A bonus system providing monetary rewards for good
performance was a performance incentive for the subjects. In addition,
penalties were assessed for prohibited behavior. At the end of each test
session, the subject's performance was evaluated with regard to bonuses
and penalties. A detailed discussion of the bonus and penalty points
schedule is included in Appendix A. The bonus point schedules appear in
Tables A-6 through A-8 on pages 58-60, and the penalty point schedules
appear in Tables A-8 through A-10 on pages 60-61.

## 2.3 Subjects

In the course of the experiment, there were 12 paid subjects. An
additional eight subjects were used for development of the training and
test procedures. The subjects were selected from the MIT student
population and no restrictions were placed on age or gender. The ages of
the subject group ranged from (approximately) 19 to 35 years old. There
were 16 undergraduate students, 3 graduate students, and 1 alumnus. The
division by gender was 3 women and 17 men.

The basic criterion for subject selection was current or recent status
as an MIT student. The proximity to an educational institution like MIT
allowed access to a population that is enthusiastic about transportation
and technology, reasonably well trained in the relevant principles of
physics, and capable of rapid assimilation of technical material. No
arbitrary limits were placed on academic experience. Instead, level of
interest in the project was used as a filter, through the use of written
preparatory material (described in Section 2.4.1).

## 2.4 Procedures

### **2.4.1 Training**

To provide the subject candidates with sufficient background in rail
systems operation, a written tutorial was prepared for their review.
Tutorial material included general rail concepts (such as block
signaling), implementation-specific design features (such as the
available supervisory control modes), and experiment details (for
example, training procedures and performance incentives). See Appendix A
for the tutorial. Prior to scheduling an initial training session,
tutorial material was distributed to subject candidates.

Written preparatory material served two purposes. One was the consistent
and efficient presentation of fundamental concepts of rail operation.
All potential subjects were exposed to the same material, in the same
format. Second, the tutorial acted as a filter for subject interest in
the project. Tutorial review required an investment on the part of the
subject candidates. Those subject candidates not sufficiently interested
were not inclined to continue with participation. As a result, the
profile of the participating subjects was appropriately biased toward
people interested in rail systems.

Subjects were trained to respond to failures through a variety of
mechanisms. Details of the potential failures and the appropriate
responses were included in the tutorial material. The subjects were then
introduced to the failures by demonstration in the early part of the
hands-on training procedures. Finally, near the end of the training
procedures, subjects were given the opportunity to experience the
failures and practice response to those failures.

Training for each subject was conducted over two sessions, each lasting
3 hours, on separate days. The first training session commenced with a
brief written quiz, to gauge the subject's understanding of the
tutorial. The quiz (Appendix B) consisted of 25 multiple-choice
questions, and required approximately 10 minutes to complete. When
completed, the experimenter and subject reviewed the quiz and discussed
any problem areas. The first training session then continued with
hands-on instruction on the simulator (Appendix E). The next half-hour
period consisted of experimenter demonstrations of the displays and
controls of the simulator, as well as the operational modes and
automation systems. Strategies for operating the train and utilizing the
automation were discussed. The subject was then instructed to take one
solo, round-trip passage of the system. At this point, no failures were
activated, and the experimenter acted as the CTC operator. Each subject
subsequently performed a second solo, round-trip, with failures
activated at expected points for practice.

The second training session was dedicated to practice and evaluation of
manual control skills. Each subject was instructed to take a full
three-round-trip shift using manual control only. The subjects were
instructed to abide by the published schedule, and were informed that
random failures might occur. The first hour was considered a practice
period, during which the subjects were encouraged to experiment with
strategies to improve their station stopping and schedule performance.
The latter 2 hours of the shift were considered a road test, during
which the performance of station stopping was measured. At the end of
the shift, the station stopping performance was evaluated, and a
recommendation for continuing with the test sessions was made, based on
the results of this evaluation.

Criteria for subject continuation with the test portion were based on
performance during the road test portion of the second training session.
Acceptance criteria included station-stopping accuracy, with less than
32.8 ft (10 m) allowed for undershoot or overshoot as a requirement. In
addition, the subjects were informed that any penalty applications of
the emergency brake, due to the ATP or alerter systems, were not
acceptable, and would result in disqualification. Schedule performance
was measured during the road test and reviewed with the subjects after
training was completed; however, schedule performance was not used as an
objective criterion for evaluation during the road test sessions.

### **2.4.2 Tests**

The test phase consisted of three separate test sessions termed *shifts*
(described in Section 2.2.4). Each shift corresponded to an operating
shift, during which the subject was expected to follow a 3-hour
operating schedule. Only one level of automation was to be used
throughout each shift. For example, if a subject was operating in a
manual control shift, the use of any automation was prohibited for the
duration of the shift.

**2.4.3 Data Collection and Processing**

In operating the vehicle simulator, a variety of vehicle state data were
recorded. Each data record included a time stamp, an event code symbol,
the total distance traveled, the current position (in terms of the
current occupied block and the position within that block), and the
current vehicle speed. With certain events, an optional field could be
recorded. The disk file format used was ASCII text.

Data records indicating the vehicle position and speed were written
continuously during the test runs, at the rate of one every 0.6 seconds.
An additional field in this record, containing a number between 1.0 and
-1.0, indicated the position of the combined control lever (and
corresponding to maximum thrust and maximum brake, respectively). In the
event that the engineer was moving the control lever, the write rate of
these records was increased to capture all of the input of the test
subject, to a maximum rate of the simulation cycle (60 milliseconds per
cycle).

Data records also were written when the user depressed any of the
control keys. These records, in conjunction with the vehicle state
records, were used to identify the actions of the test subjects. Other
data records were written whenever the vehicle changes operating state
(e.g., when an automation mode was successfully engaged). Note that a
distinction was made between an operator command that may result in
vehicle state change, and the actual change of vehicle state resulting
from the command. Separating the command from the state change allowed
identification of erroneous operator input, as well as vehicle state
changes that occurred independently of operator command.

After completing each subject test run, a raw data file was stored on
disk. Each file contained all the events, as described in Section 3,
recorded during the test run. The file format was ASCII text, and a
typical data file for each 3-hour test run occupied approximately
1.5 MB. The data files were post-processed to extract the pertinent
response data.

Immediately after the subject completed a test session, a program named
BONUS processed the raw data file. This program calculated the bonus
points that the subject earned throughout the test. In addition to the
default mode, which identified station stop performance, schedule
performance, and failure response performance, BONUS also included
operating modes which allowed isolation of any of these categories of
performance measurement. After the subjects were apprised of their BONUS
performance, BONUS calculated and stored the stopping performance and
schedule maintenance data in separate disk files.

A program named TRANSFORM calculated the response times and accuracy to
the failure events. The output of this program is an ASCII data file
containing the response time and accuracy for each failure experienced
by the subject. Comparable data from the TRANSFORM output and the BONUS
output were used for accuracy crosscheck and verification.

# 3. RESULTS

The experimental results were based on measuring subject response to
unexpected emergencies during normal operation. Each subject session
(*shift*) had a designated automation mode (manual, partial, or full),
and the pattern of emergencies experienced during a shift depended on
the *shift number* and *subject group*. As detailed in Section 2.2.4,
the automation type was counterbalanced with respect to shift number. As
a result, the failure patterns were counterbalanced with respect to
automation type.

## 3.1 Response Time to Unexpected Failures

The primary measure used to compare subject performance was response
time to unexpected failures using three distinct failure modes: brake
failure, motor failure, and track obstruction. The response time was
measured as the elapsed time between the onset of the failure and
execution of the correct response to that failure. In the case of brake
failure, brake pressure decreased at the onset of failure, and the
correct response to depress the brake pump button on the dashboard. In
the case of motor failure, the motor current was interrupted in one of
the traction motors at the onset of failure, indicated by a zero current
reading on the corresponding ammeter (on the instrument panel). The
correct response was to restore motor power through reset of the
appropriate motor circuit breaker. For track obstruction, the onset of
the failure was defined as the moment the car stops on the track, and
the correct response to apply either full service braking or the
emergency brake.

Tables 3 through 5 illustrate an analysis of the measured response times
for the 12 subjects. Due to the counterbalancing design, the exact
number of failures of each type and under each treatment varied from
subject to subject. The tables highlight the minimum and maximum
response times for each failure, as well as the mean, standard
deviation, and variance of each data set. Table 3 contains the response
time data for the brake failures. Table 4 contains the response time
data for the motor failures. Table 5 contains the response time data for
the obstruction failures. Figures 3 through 5 display the data in
box-plot representation (Tukey, 1977). The box-plot display includes a
two-segment box, identifying the median value (represented by the center
line) as well as the 25 and 75 percentile values (shown as the lower and
upper edges of the box). The 25 and 75 percentile values also are known
as *hinges*. The range between the hinges is the *H-spread*. The value
of *one step* is calculated as 150 percent of the H-spread. The *inner
fences* are defined as the bounds one step from the hinges. In the event
that the data fell within the inner fences, the whiskers show the extent
of the range. The crosses beyond the whiskers identify the *outliers*,
which are data beyond the inner fences. In all the box-plot figures,
automation level is labeled such that automation Level 1 corresponds to
manual control, automation Level 2 refers to partial automation (cruise
control and programmed stop), and automation Level 3 corresponds to full
automation (autopilot).

  -------------------------------- ------------------ ------------------ ------------------
  []{#__RefHeading___Toc90287951                                         
  .anchor}Table 3. Response Time                                         
  Data for Brake Failure                                                 

                                   Manual             Partial            Full

  Min                              5.5                5.6                4.4

  Max                              61.9               119.2              78.1

  Mean                             22.8               32.7               22.0

  Standard Deviation               16.26              30.37              16.39

  Variance                         264.41             922.35             268.67
  -------------------------------- ------------------ ------------------ ------------------

  -------------------------------- ------------------ ------------------ ------------------
  []{#__RefHeading___Toc90287952                                         
  .anchor}Table 4. Response Time                                         
  Data for Motor Failure                                                 

                                   Manual             Partial            Full

  Min                              2.7                2.6                2.9

  Max                              78.7               122.6              38.6

  Mean                             11.4               20.1               12.7

  Standard Deviation               15.11              29.49              10.62

  Variance                         228.28             869.67             112.75
  -------------------------------- ------------------ ------------------ ------------------

  -------------------------------- ------------------ ------------------ ------------------
  []{#__RefHeading___Toc90287953                                         
  .anchor}Table 5. Response Time                                         
  Data for Obstruction Failure                                           

                                   Manual             Partial            Full

  Min                              0.9                1.0                1.3

  Max                              14.8               14.8               17.4

  Mean                             4.1                4.1                5.1

  Standard Deviation               4.17               3.54               4.36

  Variance                         17.38              12.51              19.04
  -------------------------------- ------------------ ------------------ ------------------

![](media/image8.wmf){width="5.0in" height="4.0in"}

> []{#__RefHeading___Toc84667732 .anchor}Figure 3. Box-Plot Display of
> Brake Failure Response Time

![](media/image9.wmf){width="5.0in" height="4.0in"}

> []{#__RefHeading___Toc84667733 .anchor}Figure 4. Box-Plot Display of
> Motor Failure Response Time

![](media/image10.wmf){width="5.0in" height="4.0in"}

> []{#__RefHeading___Toc84667734 .anchor}Figure 5. Box-Plot Display of
> Obstruction Failure Response Time

The scientific hypothesis postulates that there exists a difference in
response time to unexpected failures, when comparing performance between
the applied levels of supervisory control. The corresponding null
hypothesis is that there are no differences in emergency response times,
with respect to automation level. The related statistical null
hypothesis is that there are no statistically significant differences in
the response times; in other words, any observed differences are due to
random sampling and measurement noise.

A typical approach would be to compare the mean response times, using a
one-way analysis of variance (ANOVA) technique. However, the ANOVA
technique assumes that the population variance of the different
treatment populations is equal. A quick inspection of the sample
variances (Tables 3 through 5) shows that observed variances are
substantially different, leading to a suspicion that this data might not
support the assumption. The observed variances are especially disparate
in the cases of brake and motor failures.

To test for equality of variance, Bartlett's test (Hald, 1952) was
applied. In summary, this test is based on the principle that the sum of
the ratios of individual treatment-group variances to overall combined
variance (i.e., all treatment groups) has a X^2^ distribution. The null
hypothesis asserts that the population variances of the three treatments
are equal, and that the observed sample variances are due to the
sampling process. The level of significance was set to 1 percent
(p=0.01). With 2 degrees of freedom in this comparison, a 1 percent
level of significance means that the null hypothesis can be refuted if
the computed X^2^ value is greater than 9.21.

Table 6 lists X^2^ values found using Bartlett's test on the response
time data. It is shown that, for the brake and motor failures, the
differences in observed variances are statistically significant at the 1
percent level, leading to the conclusion that the population variances
are not equal. Although Hald (1952) describes further quantitative tests
used to identify individual treatments, which differ significantly.
These tests are designed for experiments with a large number of
treatments and are not well suited for a three-treatment experiment.
However, inspecting variance statistics leads us to the qualitative
conclusion that, in both the brake and motor failure data, the variance
of the partial automation treatment far exceeds the other two
treatments. Thus, we can conclude that the use of partial automation
leads to a change in the visual attention bias of the engineer from
in-cab monitoring to environment monitoring, and the use of partial
automation therefore has a negative impact on the consistency of
response to unexpected brake and motor failures because the visual
attention of the engineer is biased away from the instrument panel.

With obstruction data, Bartlett's test showed there was no significant
difference between the sample variances of the three treatments. Thus,
we can conclude that the population variances of the three treatments
are equal, and sample variances can be combined to estimate the
population variance used in the ANOVA.

  -------------------------------- ------------------- ------------------- -------------------
  []{#__RefHeading___Toc90287954                                           
  .anchor}Table 6. Results of                                              
  Bartlett's Test                                                          

                                   Brake Failure       Motor Failure       Obstruction

  *X*^2^ value                     12.5                24.3                1.1
  -------------------------------- ------------------- ------------------- -------------------

A one-way ANOVA was performed on the obstruction data to identify the
significance of differences in observed mean response times. In this
test, the null hypothesis states that the population means are equal. A
significance level of 5 percent (p=0.05) was used. With values of 2
and 69 for the degrees of freedom, the null hypothesis can be refuted if
the computed F statistic exceeds a value of 3.13.

In the case of the obstruction data, the resulting F statistic from the
ANOVA was calculated to be equal to 0.4415. Since this value does not
exceed the 5 percent significance value of 3.13, the null hypothesis
cannot be refuted---there was no difference, at the 5 percent
significance level, between the three levels of automation when
comparing mean response time to the obstruction failure. Therefore, we
can conclude that varying the automation level has no effect on response
time when the engineer is presented with an unexpected obstruction.

## 3.2 Response Accuracy

In addition to the response time measures, subject response to failure
events was evaluated with respect to response accuracy. This evaluation
focused on determining whether the engineer's first response was correct
for the failure that had occurred.

For each failure scenario, there was a prescribed response pattern. This
response was specified in the tutorial material, and practiced during
the training sessions. Based on the training, a *correct* response was
judged as one in which the subject followed the procedure. A *mistake*
occurred when a subject response included an action, which was not part
of the prescribed procedure, but was not judged to have a high level of
risk to either the passengers or the machinery. An example of a mistake
is the depression of the wrong circuit breaker reset button when a motor
failure has occurred. A *serious error* is defined as a subject action,
which might have a high level of risk to either the passengers or the
machinery. An example of a serious error is opening the passenger doors
while the vehicle is moving.

Prior to the experimental tests, each subject experienced each failure
at least five times, in both expected and unexpected scenarios
(Section 2.4.1). Based on the subject responses to the failures during
the training sessions, it was observed that they were sufficiently
trained in the response procedures to allow adequate response when the
failures occurred unexpectedly.

As shown in Tables 7 through 9, very few mistakes occurred, and even
fewer serious errors occurred. Table 7 shows the response accuracy data
for the brake failures; Table 8 shows the response accuracy data for the
motor failures; Table 9 contains the response accuracy data for the
obstruction failures. In all cases, the total number of opportunities
for mistakes and serious errors is 24---each failure occurrence
represents an opportunity for inaccurate response. Tables 7 through 9
contain the total number of inaccurate responses per treatment and error
category, as well as the computed error percentages.

  -------------------------------- -------- ------- --------- ------- ------- -------
  []{#__RefHeading___Toc90287955                                              
  .anchor}Table 7. Summary of                                                 
  Brake Failure Response Accuracy                                             

                                   Manual           Partial           Full    

                                   N        \%      N         \%      N       \%

  Mistakes                         1        4.2     2         8.3     0       0.0

  Serious Errors                   0        0.0     0         0.0     0       0.0
  -------------------------------- -------- ------- --------- ------- ------- -------

  -------------------------------- -------- ------- --------- ------- ------- -------
  []{#__RefHeading___Toc90287956                                              
  .anchor}Table 8. Summary of                                                 
  Motor Failure Response Accuracy                                             

                                   Manual           Partial           Full    

                                   N        \%      N         \%      N       \%

  Mistakes                         2        8.3     2         8.3     2       8.3

  Serious Errors                   0        0.0     1         4.2     0       0.0
  -------------------------------- -------- ------- --------- ------- ------- -------

  -------------------------------- -------- ------- --------- ------- ------- -------
  []{#__RefHeading___Toc90287957                                              
  .anchor}Table 9. Summary of                                                 
  Obstruction Failure Response                                                
  Accuracy                                                                    

                                   Manual           Partial           Full    

                                   N        \%      N         \%      N       \%

  Mistakes                         0        0.0     0         0.0     0       0.0

  Serious Errors                   0        0.0     0         0.0     1       4.2
  -------------------------------- -------- ------- --------- ------- ------- -------

The best statistical analysis for comparing these data is an X^2^
goodness-of-fit test (Hamburg and Young, 1994). The goal was to
determine whether the occurrence of operator error differs significantly
in any of the test treatments. If there were no difference among the
treatments, the percentage of error would be equal across all three
treatments for each failure type and seriousness level. Thus, the null
hypothesis states that the distribution of failure occurrence is uniform
among the three levels of automation. An X^2^ value was calculated for
each category of accuracy data (three types of failures, each having two
levels of accuracy). The expected value is estimated from the observed
data, the number of degrees of freedom in each test is therefore equal
to one. At a significance level of 5 percent (p=0.05), the resultant
X^2^ value must exceed 3.84 in order to refute the null hypothesis and
conclude that there are significant differences in the observed response
accuracy. In all cases, the calculated X^2^ value was substantially less
than the decision threshold shown in Table 10. As a result, it was
concluded that there is no significant difference in response accuracy
between the treatments. This conclusion holds across all three failure
types.

  -------------------------------------------------------- --------------
  []{#__RefHeading___Toc90287958 .anchor}Table 10.         
  Computed X2 Values for Response Accuracy                 

  Test                                                     X^2^ Value

  Brake Failure, Mistake                                   0.667

  Brake Failure, Serious Error                             0.000

  Motor Failure, Mistake                                   0.000

  Motor Failure, Serious Error                             0.667

  Obstruction, Mistake                                     0.000

  Obstruction, Serious Error                               0.667
  -------------------------------------------------------- --------------

It is important to interpret these results in context. Determining the
response error data poses great difficulty, as a result of the
difficulty inherent in differentiating between an incorrect response to
a perceived failure versus an incidental action in absence of failure
perception. The major difficulty lies in the lack of a method for
determining whether the subject actually perceives the failure. In light
of this difficulty, the response accuracy results lead to limited
conclusions. In addition, the subjects' performance displayed a ceiling
effect, in that there were too few errors to detect any differences
between the treatments.

## 3.3 Subjective Evaluation

After the final test session, each subject completed an exit
questionnaire (Appendix D), which requested subjective opinions about
the correlation between situation awareness and supervisory control. The
questionnaire also asked the subjects to rank their preferences.
Tabulated results appear in Table 11. The data in Table 11 includes
responses from the 12 subjects that completed the full sequence of
tests.

  -------------------------------- ---------- ----------- ---------- ---------- ------------ ----------
  []{#__RefHeading___Toc90287959                                                             
  .anchor}Table 11. Subjective                                                               
  Situation Awareness Evaluation                                                             
  and Preference                                                                             

                                              Awareness                         Preference   

                                   High       Medium      Low        High       Medium       Low

  Manual                           9          3           0          3          4            5

  Partial                          3          6           3          3          5            4

  Full                             0          3           9          6          3            3
  -------------------------------- ---------- ----------- ---------- ---------- ------------ ----------

There is a negative correlation between the degree of automation and the
perceived situation awareness (i.e., most of the subjects correlated the
highest relative level of awareness with manual control and the lowest
relative level of awareness with full automation).[^2] However, Table 11
also shows that there is no clear correlation between preference and
automation level. This indicates that, despite their perception of a
degrading effect of supervisory control on operator awareness, some
subjects still prefer to use the supervisory control. This leads to the
belief that the individual decision to use supervisory control systems
was determined by a more complex set of criteria than the perception of
awareness.

In addition to eliciting subject preferences, the exit questionnaire
contained a section for additional comments. These, along with informal
comments during the tests, led to some conclusions, which were not
exposed objectively by the experiment. With regard to task workload, the
subjects generally felt underutilized. Even in the highest workload case
(i.e., manual control), subjects indicated that the overall task was
fairly boring. (One subject joked about naming the wayside objects to
alleviate the boredom.) It was also evident that the period of highest
workload was during station-stopping maneuvers.

With regard to the programmed stop functionality, it was generally
agreed that programmed stop was a valuable addition. The consistency in
station stopping provided by programmed stop (and by the autopilot, by
association) was roundly appreciated. However, as a result of the payoff
from the bonus system, some subjects would have preferred to use manual
control to achieve more accurate stopping performance, at the risk of
consistency, if they had been allowed to choose. It is not clear that
such a preference would exist in the absence of a bonus system.

# 4. DISCUSSION AND INTERPRETATION

The results suggest that certain types of supervisory control do impact
locomotive engineers' performance in high-speed rail systems. Of the
three automation levels used by the subjects, partial automation (cruise
control, in particular) led to a higher level of variability in response
time to brake and motor failures. This effect was not observed with
respect to grade crossing obstructions. Failure response accuracy did
not show any significant differences in performance across the three
automation treatments. This relationship held true for all three of the
failure types experienced by the subjects.

Based on the quantitative results, in combination with qualitative input
from the subjects after completion of the experiment, observed effects
are believed to be due to differences in attention allocation between
automation levels. In all of the attention allocation models presented
in Section 1, the capacity for human attention is considered a finite
resource. The attention allocation models describe different theories
regarding the division or partitioning of this limited resource.

With rail vehicle operation, the task required substantial monitoring.
The engineer was required to monitor the instruments in order to perform
speed and position control, the primary task in rail operation. In
addition, the engineer was required to monitor the vehicle systems
status displays, to detect a vehicle-based failure or emergency that
might require immediate action. Finally, the engineer was required to
observe and monitor the wayside, in order to identify the position of
the vehicle and detect any emergency situations that might require
action.

During vehicle operation, the engineer dynamically allocated limited
available attention resources. The monitoring task, perceived as "most
important" presumably, was allocated the highest proportion of
attention. The task identified as "most important" varied as the vehicle
proceeded through the system.

At higher levels of supervisory control, engineer monitoring
requirements changed. The monitoring load was highest using manual
control. The engineer was required to monitor the speed and position
displays on the instrument panel, as well as the wayside and the vehicle
system status displays. However, because the primary task was speed and
position control, attention allocation was biased toward monitoring the
speed and position instruments.

With partial automation, the requirement for monitoring the speed and
position instruments was relieved. However, the engineer was still
required to identify the positions along the route requiring active
control. For example, with cruise control, the wayside had to be
monitored in order to identify points at which the cruise control could
be engaged or disengaged, or points at which the speed setting of the
cruise control should be altered. (Because of the high vehicle mass, the
response to control inputs is slow. As a result, the engineers tended to
use manual control for gross speed changes, and use the cruise control
speed modulation for fine tuning of the set speed.) In this operational
scenario, the "most important" attention item was the position of the
vehicle along the route, and a sizable portion of the available
attention monitored the wayside and maintained awareness of vehicle
position.

In the full automation mode, the requirement for monitoring the wayside
was relieved. Although it was still important for the engineer to
maintain an awareness of the vehicle position, the autopilot now had to
identify speed change waypoints along the route and control the vehicle
speed accordingly. The locomotive engineer's role had been altered to
one, more accurately described as supervisory. In this scenario, the
"most important" task became failure and emergency situation
identification.

It is important to consider the impact of the seriousness of the
emergency. The experimental results show the diminishing effects of
supervisory control in the grade crossing obstruction emergency, as
compared to the brake and motor failures. (There were no significant
differences in emergency response performance for the grade crossing
obstruction among the three treatment groups.) Because the response time
results in the partial automation mode indicate that the attention of
the engineer was biased toward the external environment, one might
expect the response time data for the grade crossing to be shorter in
the partial automation case than the other two scenarios. With no
significant difference found in the response time to the grade crossing
obstruction implies that the subjects perceived the grade crossing
obstruction to be a more serious emergency, and therefore allocated more
attention to detection of this condition. It is also noteworthy that the
grade crossing obstruction could occur only at a few known points on the
track. Knowing about the potential emergency, subjects may have paid
greater attention to the grade crossings as they approached them,
decreasing the likelihood of differences in the response times to
obstructions.

# 5. CONCLUSIONS AND RECOMMENDATIONS

In summary, we can draw the following conclusions:

1\. Certain types of supervisory control had a significant effect on
variance in response times to the brake and motor failures. In both
types of failure, the highest variance was observed with partial
automation (i.e., the engineer used the cruise-control and
programmed-stop systems). Increase in response time variance can be an
indication of an operator out-of-the-loop condition, suggesting degraded
situation awareness on the part of the locomotive engineer.

2\. Different levels of supervisory control had no significant effect on
the response time to the grade crossing obstruction failures, suggesting
that engineers were equally attentive to risks in the grade crossings,
despite the level of supervisory control. Because the grade crossings
occurred at fixed locations, the opportunities for grade crossing
obstruction occurred at those known fixed points. This suggests that it
might be easier for engineers to prepare for obstruction response than
for brake and motor failures, which could occur at any point along the
travel route.

3\. The response accuracy data, for all failure types, imply that no
significant differences in response accuracy exist as a result of using
supervisory control. However, this analysis is limited by the quantity
of data obtained in the experiment. The occurrence of such errors may be
rare enough that true estimates of the relative error rate could not be
obtained with the limited number of data points. Expanding the
experiment to better capture these effects was beyond the scope of this
experiment.

4\. The subjective preference data indicate that the subjects perceived
a difference in their own situation awareness between the presented
levels of supervisory control. Specifically, the subjects felt that
increasing the level of supervisory control led to a degradation in
awareness. Despite this trend, some subjects preferred to use the
automation, leading to the conclusion that the selection of automation
level is governed by additional factors.

Based on these conclusions, we can also draw some additional inferences
about the effects of supervisory control. Observed differences in
behavior were related to the nature of the vehicle speed control loop
and shifts in attention resources. In manual mode, the primary task of
the locomotive engineer was speed regulation, and the engineer made
heavy use of the instruments to perform the task. Although the engineer
also observed the wayside for position fixes, braking points, and
potential obstructions in grade crossings, the attention allocation was
biased toward the instruments. When cruise-control operation was
invoked, speed regulation was relaxed. When using cruise control, the
engineer was relieved from the lower level control loop, and a greater
portion of operator attention was available for greater concentration on
the wayside for observance of braking points and other pertinent
information. In the process, less attention was directed toward the
instrument panel, leading to a higher variability in response time to
failures that are detected via the instrument panel. In autopilot mode,
the need to observe the wayside was relaxed, as braking points were
automatically monitored by the autopilot. The operator could then
redirect the available attention resources toward monitoring the
instrument panel.

Despite the time spent by each subject, it is believed that performance
effects due to complacency were not observed. Although 15 hours per
subject is a substantial level of participation, it does not nearly
approach the level required to induce complacency and boredom.

Advantages of supervisory control include performance consistency. In
general, when comparing automatic control against human control,
automatic control provides better performance with regard to consistent
and accurate behavior in routine tasks, while the human controller is
better suited to adaptation under unexpected circumstances. These
characteristics hold true in rail operation. The automatic control
systems in the high-speed rail simulator provided tightly maintained
speed control (cruise control), consistent station stopping performance
(programmed stop), and accurate tracking of pre-determined speed
trajectories (autopilot).

However, when considering the overall human-machine system performance,
it was observed that the use of cruise control led to a higher
variability in the human response to certain emergency situations,
thereby offsetting the consistency that had been gained through use of
the automatic system. The overall system performance, relative to the
specific failures tested, was in fact degraded by this partial
automation when compared to the fully manual scenario.

Implementing full automation would be useful in high-speed rail systems.
Full automation (autopilot) provides advantages in stopping and schedule
consistency, and the overall safety-related performance of the vehicle
operators was not degraded when compared to the fully manual control
scenario. Full automation use freed sufficient attention resources to
maintain or improve response to vehicle-related failures, without
significant degradation in response to wayside-related failures.

However, there is concern regarding potential effects of complacency and
boredom of incorporating a fully automatic vehicle control system for
high-speed rail systems. Although degradation of emergency performance
in wayside-related failures was not observed in the short-term, it is
not clear that such performance would be maintained over longer-term
operating periods. The subjective assessment that situation awareness is
degraded when using full automation provides cause to suspect the
potential for longer-term effects. Additional research should be
conducted to further explore the effects of supervisory control on
operator complacency.

The experimental results also raise concerns with regard to
safety-related system performance in using cruise control in high-speed
rail systems. Cruise control use seems to bias the operator's visual
attention away from the in-cab instruments and toward the external
environment. This is a benefit in the traditional automotive application
of cruise control as attention to the environment results in improved
vehicle control performance in dense and highly dynamic traffic.
However, in the high-speed rail application, a high percentage of the
operator's attention should be focused on monitoring the vehicle
systems, and the use of cruise control degrades performance of the
operator with regard to vehicle systems monitoring. Because the
operator's visual attention is directed out of the cab, the operator
performance relative to grade crossing safety was not compromised to any
significant degree.

It is possible that the use of a head-up display (HUD), in conjunction
with cruise control, might ameliorate the effects of the attention bias
induced by the cruise control. A properly designed HUD would display the
pertinent systems state information in the line of sight of the operator
when looking out the windshield toward the environment. Having these
data in the direct field of view would potentially result in faster
response times to systems failures (assuming that the HUD provides a
detectable indication of the system failures). It is suggested that a
follow-up experiment be conducted to evaluate the changes in operator
performance that result from the use of an HUD in conjunction with
cruise control.

# APPENDIX A. TRAINING TUTORIAL

This appendix presents the written tutorial document, provided to all of
the candidate subjects prior to the first training session in the
simulation system. The tutorial appears exactly as presented to the test
subjects, with the exception that the reference numbers for the figures
and tables have been altered to reflect their location in this report
(for the purpose of clarifying references to the figures from other
sections of the report).

#### Experiment --- General

You are participating in an experiment which will answer questions about
the relationship between control automation and operator situation
awareness in high-speed rail operation. Although the control of rail
vehicles and systems can be automated, there are concerns about
potential side effects when using automated control in high-speed rail
systems. In order to explore these effects, test subjects like yourself
are asked to operate a simulated high-speed train in a virtual reality
environment. Your actions are measured during the tests, and later
analyzed.

Participation in the experiment consists of two phases. The first phase
is a period of training, which consists of a 3-hour instruction session
and a 3-hour practice session. Prior to the instruction session, you are
asked to review this document, which is a tutorial on the operation of
the simulated train vehicle. At the start of the instruction session,
you will take a written review quiz, which will gauge your understanding
of this material. The written review quiz consists of 25 multiple-choice
questions, and is closed book. The quiz is graded immediately after
completion. You will then be directed by the instructor through a set of
training instructions, which will familiarize you with normal operation
of the vehicle. You will also be exposed to a set of emergency
scenarios, allowing you to learn the proper responses to these
situations.

The second half of the training phase consists of a combination practice
and test session. This session is conducted like a regular experiment
session, in that it is a 3-hour session consisting of three round trips
between the two stations in the system. The first hour is considered to
be the practice portion. During this period, you will reacquaint
yourself with the operation of the train simulator. The remaining 2
hours is considered a "road test" which will further gauge your
abilities to operate the train. Your performance with regard to speed
compliance, signal compliance, and station stopping accuracy will be
evaluated. If you pass this test, you will be ready ("certified") to
perform the experiment trials. You will be eligible for payment for the
training phase upon completion of the practice and test session.

The second phase consists of a set of experiment trials. These
experiment trials will take place in three separate 3-hour sessions.
Each session is called a **shift**, and corresponds to a shift of
operation in an actual rail operation. During each shift, you will
operate the simulated vehicle as if it were part of an actual rail
system. Once underway, you will be expected to remain at the simulator
controls ("in the vehicle") until the shift is complete. Brief break
periods are allowed, as approved by the experimenter (acting as the CTC
operator \[and also called the train dispatcher\]). The three experiment
trials will be conducted on 3 separate days. You will be eligible for
payment for the experiment trials upon completion of the third shift.

Payment for the experiment is through the MIT voucher payroll system.
The rate of pay is \$25 per 3-hour session. Therefore, the subtotal for
the training phase is \$50, and the subtotal for the experiment phase is
\$75, resulting in a total payment of \$125. (Payment for the experiment
phase is subject to performance bonuses, as well as penalties that
result from illegal behavior---please refer to the section titled
"System Operation --- Operator Performance Requirements" for details.)
Subjects are paid for each phase completed, regardless of performance.
However, subjects that do not pass the training phase will not be
allowed to continue with the experimental phase. Subjects can elect
payment for the training and experimental phases to be separate
(resulting in two checks), or payment for the two phases can be lumped
together into one check.

This tutorial is organized so that the reader can learn the fundamentals
of rail system operation in a logical order. Important terms and
concepts are highlighted with bold-faced text.

## System Operation --- General {#system-operation-general .Appendix-2}

The rail system used in the experiment is a fictitious rail system
connecting two stations, named West Station and East Station (Figure
A-1). The two stations are connected via a single track that is 31 miles
(50 km) in length. At each end of system, beyond the stations, there is
a loop of track that is used to turn the vehicles around for the return
trip.

![](media/image11.emf){width="3.1944444444444446in"
height="2.8333333333333335in"}

> []{#__RefHeading___Toc84667735 .anchor}Figure A-1. Track Layout,
> Simulated Rail System

The system is operated as a high-speed shuttle between these two
stations. There is one vehicle in operation. That vehicle will travel
from one station to the other, discharge passengers, loop around to
reverse direction, board new passengers, and proceed to the other
station. This procedure is followed throughout the duration of the
shift.

Operation of the system is coordinated through a **central traffic
control** operator (**CTC**). This person is located in a fixed position
in the system, and has access to the state of all the vehicles operating
in the system. The CTC operator has the task of coordinating the
operation of several vehicles that must share resources (such as the
track system). To carry this task out, the CTC operator has control over
the switches in the system, and can set signal levels manually. In
addition, the CTC operator is able to communicate directly with vehicle
operators.

The **wayside** is a general term which refers to all objects in the
environment which do not move. This includes items such as the ground,
the track, the signal lights, the surrounding trees and buildings, and
so on.

**System Operation --- Block Signal System**

Rail systems have traditionally used a system known as **block
signaling** for control of trains in the rail system. With block
signaling, the track is divided into fixed length chunks known as
**blocks**. While the length of each block does not change, different
blocks are not necessarily of equal length. Typically, shorter block
lengths are used in the near vicinity of stations, while longer block
lengths are used in regions away from the stations. Block lengths are
generally on the order of one mile. In the road system used in the
simulation, all blocks between stations are 1.2 miles (2 km), and all
blocks in the loop sections are 0.6 miles (1 km) in length.

At the boundaries of each block is a **signal light**. This signal light
displays a color-coded signal, which indicates the maximum speed
permitted throughout the block. The signal acts as a dynamic **speed
limit**, and it is the responsibility of the vehicle operator to
identify the signal as the block boundary is approached and set the
vehicle speed accordingly.

A fundamental rule in block signaling is that no more than one train can
occupy a block at any given time. A red signal is used to indicate that
another train currently occupies the block, and the approaching train is
not permitted to enter that block. The blocks that precede the occupied
block have signal levels which ensure that the train can be slowed in
time to stop before entering the occupied block.

In addition to the speed limits imposed by the block signal system,
there are also **civil speed limits**, which are static. These limits
are either memorized or written down by the operator. In all cases, the
prevailing speed limit is the lesser of the block signal limit and the
civil speed limit.

The exact specification of signals used and speed limits associated with
those signals is a design parameter for a rail system, and varies from
system to system. In the simulation system, a five-aspect signaling
system is used. This means that there are five color codes used in the
system, with the codes defined as shown in Table A-1.

If a train was occupying block 157, then the signal at the entrance to
block 157 would show STOP (red), the signal at the entrance to block 156
would show RESTRICTED (red/yellow), the signal at the entrance to block
155 would show APPROACH (yellow), the signal at the entrance to block
154 would show APPROACH MEDIUM (green/yellow), and the signals at blocks
prior to 154 would show CLEAR (green). The speed limits apply to the
entire block, which means an approaching train must reduce speed to the
limit before reaching the entrance of the block. So, in this example
scenario, another train approaching the train in block 157 must be going
slower than 143 mph (230 km/h) before entering block 154, slower than 93
mph (150 km/h) before entering block 155, and slower than 50 mph (80
km/h) before entering block 156 (see Figure A-2).

  -------------------------------- ------------------- ----------------------------------
  []{#__RefHeading___Toc90287960                       
  .anchor}Table A-1. Rail Signal                       
  Codes                                                

  **COLOR**                        **CODE**            **ACTION**

  Red                              stop                not permitted to enter the block

  red/yellow                       restricted          maximum speed of 50 mph (80 km/h)
                                                       in this block

  Yellow                           approach            maximum speed of 93 mph (150 km/h)
                                                       in this block

  green/yellow                     approach medium     maximum speed of 143 mph (230
                                                       km/h) in this block

  Green                            clear               maximum speed of 186 mph (300
                                                       km/h) in this block
  -------------------------------- ------------------- ----------------------------------

![](media/image12.emf){width="6.541666666666667in"
height="1.6111111111111112in"}

> []{#__RefHeading___Toc84667736 .anchor}Figure A-2. Block Signaling
> System

Located throughout the system are position markers known as
**mileposts**. The use of these by vehicle operators is discussed in
detail in the next section. It is important to note the difference
between block signals and mileposts. At the entrance to each block,
there is a signal board which identifies the block number and displays
the current signal level for that block. Because block boundaries occur
at 1.2 mi (2 km) intervals on the main line in this system, there is
also typically a milepost at the block boundaries. So, for example,
block 13 comprises the distance of track between mileposts 26 and 28.
This provides opportunity for confusion: When traveling eastbound, the
entrance to block 13 is marked by mile post 26, but when traveling
westbound, the entrance to the same block occurs at mile post 28.
Operators must take care to differentiate between block identifiers and
mileposts, as the relationship between them is not as simple as it might
at first appear.

## Vehicle Operation --- User Interface {#vehicle-operation-user-interface .Appendix-2}

The user interface for the train simulation consists of two graphics
displays, a computer keyboard, and the combined control lever. The two
graphics displays are placed side by side on a table, with the computer
keyboard between them and the combined control lever to the right.

The display to the right is the instrument panel for the train. A
schematic drawing of the instrument layout is shown in Figure A-3. In
this figure, we can locate the speedometer, the secondary gauges (brake
tank pressure, wheel bearing temperature, and trolley voltage), the mode
indicators, the warning indicators, the motor current meters, the system
clock, and the communications display.

![](media/image13.emf){width="6.291666666666667in"
height="5.430555555555555in"}

[]{#__RefHeading___Toc84667737 .anchor}Figure A-3. Instrument Panel
Layout

The graphics display on the left is the out-the-window view port. This
is also known as the **windscreen**. In this view, the operator is able
to view the world outside the vehicle. The scene presented is a night
scene, with wire-frame objects along the wayside. This port also
provides a head-up display for assistance in station stopping (described
in a later section), as well as an indication of collision with a
highway vehicle in a grade crossing (described in a later section).

The **combination control lever** is a joystick-like lever to the right
of the keyboard (beside the instrument panel display). Although there
are two handles on the control, only the right black-handled lever is
used. This lever is used to control both the thrust and braking
commands, with the forward (up) direction for thrust and the backward
(down) direction for braking. The center position (coast) is notched for
reference.

The computer keyboard is used for both control buttons and alphanumeric
communications input. The function buttons in the top row have specific
operator control functions, described in the following sections. The
main part of the keyboard is for entry of communications messages. These
messages are typed in, and are displayed in the communications area of
the instrument panel. While a message is being composed, it appears in
the lower portion of the communications display, and is visible to only
the operator. When the carriage return is depressed, the message is
"sent" to all other operators on the system, including the CTC operator.
The message then appears in the "receive" area (top portion) of the
communications display. The messages that appear in the top portion are
visible to all operators in the system.

## Vehicle Operation --- Head-Up Display for Station Stopping {#vehicle-operation-head-up-display-for-station-stopping .Appendix-2}

Because of the braking dynamics of rail trains, one of the more
challenging aspects of train operation is stopping the vehicle at an
appropriate point in the station. This becomes very important when the
vehicle must be stopped at a precise point, for example, to allow proper
alignment of handicapped ramps.

Because of the limited perspective through the out-the-window viewport,
a decision aid is provided in the train simulator to assist the vehicle
operator in this task. The aid takes the form of a **head-up display**
(or HUD), which is a graphical icon superimposed on the windscreen.
(Head-up displays are commonly found in military aircraft, where a set
of instrument displays is projected on the windscreen so that the pilots
can monitor the vehicle status while concurrently performing other
visual tasks.) The HUD in the train is a yellow rectangular box, which
appears when the train is within the confines of the station. When the
HUD is aligned with the back wall of the station, the train is at the
ideal stopping point in the station.

In the event that the vehicle comes to a stop before it is in the
station (i.e., before the HUD appears), the operator can slowly bring
the vehicle into the appropriate position. If the vehicle comes to a
stop after the station is passed (overshoot), the operator must contact
the CTC to report the situation and request further instruction. Under
no circumstances should the vehicle operator open the passenger doors if
the vehicle is not within the boundaries of the station.

## Vehicle Operation --- Speed and Position Control {#vehicle-operation-speed-and-position-control .Appendix-2}

The most important task required of a train vehicle operator is the
control of vehicle speed. The operator uses the position of the vehicle
to obtain the current speed limit, through a combination of civil speed
limits (which are memorized or written down) and block signal states
(which are observed on the wayside). The operator then uses the traction
motor system and the braking system to adjust the speed of the vehicle
accordingly.

The vehicle operator gets information about vehicle speed through the
speedometer, which is located on the instrument panel in the locomotive
cab. In the train simulation, this speedometer is implemented as a round
dial gauge. The units shown are kilometers per hour (km/h), and the
available range of speeds is from 0 to 217.5 mph (350 km/h). The major
increments of the gauge display are 31.1 mph (50 km/h), with minor
increments each 6.2 mph (10 km/h). The red pointer indicates the current
speed, while the smaller yellow pointer (underneath the red pointer)
indicates the set speed (used by the automation systems).

Another important task of the vehicle operator is monitoring the
position of the vehicle in the rail system. Monitoring the
out-the-window view accomplishes this. Along the wayside, distance is
marked through the use of "mile posts." Typically, at one-mile
intervals, a post is placed on the wayside with numbers indicating the
mile marker. Vehicle operators use the difference between posts to
measure distances along the road. Because the simulation system is
implemented using the metric system, these posts are referred to as
"mile posts," and are located at one-kilometer intervals.

When approaching a stopping point, such as a station, the vehicle
operator uses out-the-window cues to identify points at which the brakes
should be applied to stop at a particular position. Because of the high
mass of the train (with resultant high momentum when in motion),
accurately braking the vehicle requires relatively long lead times for
the control commands. As a result, it is common for train operators in
real systems to use stationary objects on the wayside as braking point
markers. Learning the proper braking points represents a significant
part of the training process for vehicle operators.

To assist in learning and remembering the appropriate braking points,
there are significant landmarks placed in the wayside environment at
points that help locate the braking points. During the training phase,
the subject is provided with a three-page chart titled "Brake Point
Specification Worksheet." This worksheet shows a schematic diagram of
the track, and identifies the speed restricted areas, as well as the
braking points for these areas. The chart also identifies the landmarks
which are placed near each braking point.

Blocks 0, 1, 11, 12, and 13 all have speed restrictions, due to the
grade crossings present in these blocks. When traveling from West
Station to East Station, the first major braking point occurs at
milepost 17, to slow from 186 mph (300 km/h) to 62 mph (100 km/h) before
reaching block 11. At 17, on the right, there is a group of 5 red
columns that serve as a landmark. The next major braking point is at
milepost 44, for stopping at East Station. The landmark at this point is
a large red building on the left, surrounded by a blue fence. When
traveling from East Station to West Station, the first braking point
occurs at milepost 33, to slow in time for the speed restriction at
block 13. In this case, the landmark is a red pedestrian bridge over the
track. Finally, at milepost 9, there is a large red building with a
green pointed crown on its roof, located to the left side, signifying
the braking point for entrance to block 1. These landmarks are noted on
the Brake Point Specification Worksheet.

The skill of stopping the train at the station is a critical component
of vehicle operation in passenger rail systems. Tables A-2 and A-3 are
provided to assist in learning this skill. In the simulation system, the
ideal stopping point in the station is defined as the point at which the
front of the train is just underneath the block signal sign. As
described in the previous section ("Vehicle Operation --- Head-Up
Display for Station Stopping"), there is a decision aid to assist in
locating this position. Table A-2 is a summary of the relationship
between the position in the station and the visual cues in the
out-the-window view. Table A-3 provides a summary of the braking
distances from low speed, using full service braking. From the
information provided in these tables, the following strategy for
accurate station stopping can be determined:

1\) Enter the station at about 21.7 mph (35 km/h).

2\) Apply full service braking as the vehicle passes through the
entrance doorway.

3\) When the vehicle slows to 6.2 mph (10 km/h), ease off the brakes to
coast.

4\) When the middle of the block signal sign intersects the top of the
windscreen, re-apply full service braking.

In addition, Table A-3 shows that entrance to the station at a speed in
excess of 24.9 mph (40 km/h) will result in overshoot, and may result in
a missed station stop.

## Vehicle Operation --- Control Modes {#vehicle-operation-control-modes .Appendix-2}

There are four basic **control modes** available with the high-speed
rail simulation vehicle: a) manual mode, b) cruise control mode,
c) programmed stop mode, and d) autopilot mode. The latter three are
considered **automatic control modes** because part of the vehicle
control task is performed by a computer-based control system.

In **manual mode**, the vehicle operator is responsible for all aspects
of vehicle control. Using the **combination control lever**, the vehicle
operator provides all thrust and brake commands required to achieve
speed and position control of the vehicle.

In **cruise control mode**, the automatic control system applies the
appropriate level of thrust force to maintain a constant speed setting.
The vehicle operator is responsible for determining the proper speed for
the conditions, and then setting the cruise control system for that
speed.

  -------------------------------- ---------------------------------------
  []{#__RefHeading___Toc90287961   
  .anchor}Table A-2. Relationship  
  Between Vehicle Position and     
  Out-the-Window View              

  **Position, relative to stopping **visual cue**
  point**                          

  -360.9 ft (-110 m) (undershoot)  entrance doorway is just visible in
                                   windscreen

  -328 ft (-100 m)                 HUD (yellow rectangle) appears on
                                   windscreen

  -180.4 ft (-55 m)                HUD top bar at top of block signal sign

  -180.4 ft (-40 m)                HUD top bar across middle of block sign

  -91.8 ft (-28 m)                 HUD top bar at bottom of block sign

  -65.6 ft) (-20 m)                HUD top bar midway between bottom of
                                   block sign and top of back wall

  -39.4 ft (-12 m)                 top of block sign at top of windscreen

  -29.5 ft (-9 m)                  middle of block sign at top of
                                   windscreen

  -19.7 ft (-6 m)                  bottom of block sign at top of
                                   windscreen

  0                                HUD aligned with back wall

  +98.4 ft (+30 m)                 top of HUD halfway down upper portion
                                   (purple) of back wall

  +187 ft (+57 m)                  HUD top bar at top of exit doorway

  +239.5 ft (+73 m)                HUD side bars at sides of exit doorway

  +295.3 ft (+90 m)                exit doorway is just visible in
                                   windscreen

  +328 ft (+100 m) (overshoot)     HUD display disappears
  -------------------------------- ---------------------------------------

  ----------------------------------- -----------------------------------
  []{#__RefHeading___Toc90287962      
  .anchor}Table A-3. Summary of       
  Low-Speed Braking Distances         

  **speed (mph)**                     **stopping distance (feet) (FSB)**

  24.9 (40 km/h)                      363 (110 m)

  21.7 (35 km/h)                      280.5 (85 m)

  18.6 (30 km/h)                      204.6 (62 m)

  15.5 (25 km/h)                      145.2 (44 m)

  12.4 (20 km/h)                      92.4 (28 m)

  9.3 (15 km/h)                       52.8 (16 m)

  6.2 (10 km/h)                       26.4 (8 m)

  3.1 (5 km/h)                        6.6 (2 m)
  ----------------------------------- -----------------------------------

In **programmed stop mode**, the automatic control system applies the
appropriate level of brake force to stop the vehicle at a specific
position. The vehicle operator is responsible for determining the
appropriate position to invoke the programmed stop mode.

In the **autopilot mode**, the automatic control system applies the
appropriate level of thrust and brake forces to follow a predetermined
speed trajectory. The vehicle operator is responsible for invoking the
autopilot control mode. Once vehicle control has been assumed by the
automatic control system, all necessary vehicle control commands are
provided by the control system. The task of the operator is reduced to
monitoring the vehicle and wayside systems, looking for potential
problems in operation.

## Vehicle Operation --- Traction System {#vehicle-operation-traction-system .Appendix-2}

In general, high-speed trains are propelled by electric motors, called
**traction motors**. Power for the traction motors is fed from a
high-voltage line, usually on overhead wires. The power is then passed
through a **motor controller**, which governs the amount of power
supplied to the traction motors based on the control command of either
the vehicle operator or automatic control system.

In the manual operating mode, the vehicle operator is in direct control
of the traction power via the combination control lever. Moving the
lever forward increases the level of power, and consequently, the
acceleration of the vehicle. When the control lever is in the center
position, no tractive power is provided, and the vehicle coasts. Moving
the lever back increases the braking force.

In the three automatic modes (autopilot, cruise control, and programmed
stop), the level of tractive power is determined automatically by the
control system, and a control command is provided to the traction motor
controller.

When tractive power is commanded, either manually or automatically, the
motor controller provides electrical power to the traction motors. The
tractive force provided by the motor is proportional to the current
through the motor windings. The dashboard display includes four current
meters (**ammeters**), which display the level of current through each
of the four traction motors. In manual mode, these displays will respond
directly to the input at the combination control lever, while in
automatic mode, they provide a mechanism for observing the operation of
the automatic systems.

The traction motors are protected by **circuit breakers**, which will
interrupt the flow of electrical power to the motors if a failure
condition is detected. Each of the four motors has a separate circuit
breaker. Under certain circumstances, the circuit breaker for a single
traction motor can be tripped, which results in no power being provided
to the traction motor. The occurrence of this event can be observed
through the ammeters---when one (or more) of the ammeters does not
respond with the others, the circuit breaker for that traction motor has
tripped and must be reset.

The procedure for resetting the circuit breaker is as follows: a) Remove
all power from the other traction motors, by moving the combination
control lever to a coast or brake position. b) Depress the appropriate
traction motor reset switch (F1 through F4 on the control panel).

c) Apply tractive power manually, using the combination control lever.
d) Resume the control mode previously in use. If any of the traction
motor reset switches are depressed while power is applied, a safety
system causes all of the traction motor circuit breakers to trip,
preventing motor overload. In this event, all of the circuit breakers
must be reset to resume proper operation.

#### Vehicle Operation --- Brake System

Train brakes utilize air pressure, which is stored in tanks on the
locomotive. Under non-braking circumstances, the pressure in the tanks
prevents the brakes from engaging. When the brakes are applied, pressure
is released from the tanks, causing the brake shoes to contact the
rotating surfaces and resulting in a force, which slows the vehicle. An
important variable to be monitored by the vehicle operator is the
**brake tank pressure.**

The braking system has two separate modes of operation, **service
braking** and **emergency braking**. During normal operation, the
vehicle operator uses service braking to apply various levels of braking
force to the vehicle. In this mode, the combination control lever
controls the level of service brake application. The level of braking
force can be varied continuously throughout the available range.
Application of the maximum available braking force is known as **full
service braking.**

In the emergency braking mode, all of the pressure in the brake system
is released, resulting in the maximum possible brake force. In general,
this is not a desirable event, as the forces generated result in severe
deceleration, which can damage equipment and can cause discomfort or
injury to passengers. The vehicle operator can command application of
the emergency brake via a control switch on the instrument panel. Also,
in certain operational modes, the emergency brake will be applied as a
result of dangerous conditions or improper control actions. Such
application of the emergency brake is known as a **penalty
application.**

During application of the emergency brakes, the emergency brake
indicator will be lit (red). Once the emergency brakes have been
applied, they cannot be released until the vehicle comes to a complete
stop. When the vehicle is stopped, the control lever is pulled back to a
position that results in application of the service brake, and the
emergency brake reset switch is depressed. At that point, the emergency
brake indicator light will be extinguished, and the vehicle will be
ready to continue with normal operation.

The pressure in the brake tanks is indicated by the brake tank pressure
gauges, which are located on the instrument panel. In the train
simulation, there are two brake tanks, one each for two separate halves
of the brake system. The corresponding gauges are round dial gauges,
calibrated in units of pounds per square inch (psi), with a range from
0 to 100 psi. The normal reading when the brakes are not applied (i.e.,
the nominal high pressure) is approximately 98 psi. When full service
braking is applied, the pressure drops to approximately 22 psi, and the
pressure further drops to 0 psi under emergency braking.

If there is a failure in the braking system, one or both of the tanks
may show a reduction in tank pressure. This situation will result in the
brakes being applied without being commanded by either the operator or
the control system. The procedure for rectifying this situation is to
switch to an alternate brake compressor. This is accomplished by
depressing the brake compressor switch (F10 key). The pressure in the
faulty tank will then rise to the appropriate level.

## Vehicle Operation --- Cruise Control Operation {#vehicle-operation-cruise-control-operation .Appendix-2}

The function of the cruise control system is to maintain a constant
vehicle speed. The vehicle operator invokes the cruise control by
depressing the cruise control enable switch (F5 key) while the vehicle
is traveling at the desired speed.

When the cruise control mode is enabled, the cruise control indicator
light (green) is illuminated, and the yellow pointer on the speedometer
indicates the set speed. When the cruise control is first selected, the
control system will adjust itself to determine the proper level of
thrust force required to maintain the selected speed. As a result, there
is a small amount of "hunting" around the set speed at first. The system
then settles down to the set speed, and small fluctuations in the motor
current indicate that the control system is operating.

The vehicle operator can alter the set speed by depressing the
"up-arrow" and "down-arrow" keys on the keyboard. With the depression of
each key, the set speed is adjusted up (or down) by 0.6 mph (1 km/h).
This feature allows the operator to "fine-tune" the set speed. When the
operator adjusts the set speed down to a lower speed, the vehicle will
coast down to the lower speed.

From cruise control mode, the vehicle operator can either select manual
mode or programmed stop mode. By pulling back on the combination control
lever, the braking system is actuated, and the vehicle returns to manual
mode. The vehicle operator can also directly select programmed stop mode
from cruise control mode.

For reasons of safety, application of the brakes will always disengage
the cruise control system. As a result, it is not possible to engage the
cruise control system when the brakes are in use. If the operator
attempts to engage the cruise control system while the brakes are
applied, the system will not respond to that mode command, and the
vehicle will remain in manual mode.

#### Vehicle Operation --- Programmed Stop Operation

The function of the programmed stop system is to bring the vehicle to a
smooth, controlled stop at a predetermined location (specifically, at
the end of the currently occupied block). The vehicle operator invokes
the programmed stop function by depressing the programmed stop enable
switch (F6 key) while the vehicle is traveling at a steady speed that is
less than 49.7 mph (80 km/h).

The programmed stop mode must not be invoked when the vehicle is
traveling at a speed greater than 49.7 mph (80 km/h). If the vehicle
speed is greater than 49.7 mph (80 km/h), activating this mode will
result in a penalty application of the emergency brakes. In addition,
the programmed stop controller must keep track of the distance between
the train and the stopping position (the end of the current block). If
the programmed stop mode is invoked while the vehicle is too close to
the end of the block to be stopped using full service braking, the
emergency brakes will be applied in an attempt to stop the vehicle
before the end of the block.

When the programmed mode is enabled, the programmed stop indicator light
(orange) is illuminated. The vehicle operator can return to manual mode
by pulling back on the combination control lever to activate the braking
system.

For reasons of safety, application of the brakes will always disengage
the programmed stop control system. As a result, it is not possible to
engage the programmed stop mode when the brakes are in use. If the
operator attempts to engage programmed stop operation while the brakes
are applied, the system will not respond to that mode command, and the
vehicle will remain in manual mode.

## Vehicle Operation --- Autopilot Operation {#vehicle-operation-autopilot-operation .Appendix-2}

The function of the autopilot system is to perform all thrust and brake
commands required to follow a pre-determined speed trajectory. The
vehicle operator invokes the autopilot function by depressing the
autopilot enable switch (F7 key) while the vehicle is in motion. For
best performance, the vehicle must be traveling at a speed greater than
6.2 mph (10 km/h) when the autopilot is activated.

When the autopilot mode is enabled, the autopilot indicator light (blue)
is illuminated. In addition, the yellow pointer on the speedometer
indicates the pre-determined speed setting. The vehicle operator can
return to manual mode by pulling back on the combination control lever
to activate the braking system.

For reasons of safety, application of the brakes will always disengage
the autopilot control system. As a result, it is not possible to engage
the autopilot mode when the brakes are in use. If the operator attempts
to engage the autopilot system while the brakes are applied, the system
will not respond to that mode command, and the vehicle will remain in
manual mode.

#### Vehicle Operation --- Alerter System

The **alerter system** is a safety system on the train, which reduces
the risk of accidents that are due to operator incapacitation or
inattention. The principle behind the system is the requirement for
periodic input from the vehicle operator, to determine if the operator
is still functional at the controls. If the operator does not respond in
a reasonable amount of time, the system assumes that the operator is
incapacitated, and applies the emergency brakes to stop the vehicle.

The alerter system, as implemented in the high-speed rail simulation, is
similar to those used internationally in actual rail systems. If the
operator does not depress the alerter response button ("escape" key)
within a period of 42 seconds from the last depression of that button,
the system issues a warning reminding the operator to do so. The warning
consists of a flashing yellow indicator light and an audible chime. If
the operator does not respond within 10 seconds of the onset of the
warning, the system assumes that the operator is incapacitated and
applies the emergency brakes. In this scenario, both the alerter warning
light and emergency brake light will be illuminated.

One type of alerter system, known as a **smart alerter**, will
acknowledge other command actions by the operator as a response to the
alerter system. For example, if the alerter issues a warning and the
operator pulls back on the combined control lever to apply the brakes,
the alerter system interprets that braking command as a response, and
ceases to issue the warning. This type of system presents less of a
workload to operators under hectic conditions. The alerter system
implemented in the simulation system is a smart alerter system.

#### Vehicle Operation --- ATP System

The **automatic train protection system** (**ATP**) is a safety system
on the train. Its function is to reduce the risk of accident by
preventing an overspeed condition to occur. An overspeed condition is
defined as operation of the vehicle at speeds in excess of either the
civil speed limit or the signal speed limit.

The ATP system continuously monitors the speed and position of the
vehicle. It also identifies the state of the block signal when the
vehicle enters a block. Based on the position of the vehicle and the
block signal state, the maximum allowable speed is determined. If the
vehicle exceeds that speed by no more than 9.3 mph (15 km/h), a warning
is issued. The warning consists of a flashing yellow indicator light and
an audible chime. If the speed is not reduced to a level less than the
limit within a period of 20 seconds, or if the speed is greater than 9.3
mph (15 km/h) over the limit, a penalty application of the emergency
brakes is invoked. In this scenario, both the ATP warning light and
emergency brake light will be illuminated.

## Vehicle Operation --- Door Control {#vehicle-operation-door-control .Appendix-2}

The vehicle operator is responsible for controlling the state of the
**passenger doors**. The doors are to be opened when the vehicle is
stopped in the station. In principle, the doors must not be opened at
any other point in the system, for the protection of the passengers.

Door control is accomplished through the door control button (F8
button). The door indicator light (red) on the instrument panel shows
the state of the doors. When the light is illuminated, the doors are
open. Depressing the door control button while the vehicle is stopped
will cause the state of the doors to change --- if the doors are open,
they will be closed, and if the doors are closed, they will be opened.

A safety system prevents the doors from being opened while the vehicle
is in motion. Door control commands while the vehicle is in motion will
be ignored. If the vehicle is stopped with the doors open, any attempt
to move the vehicle will cause a penalty application of the emergency
brake.

## Vehicle Operation --- In-Cab Signal System {#vehicle-operation-in-cab-signal-system .Appendix-2}

In many rail systems using block signal technology, the signal
information is available only on the wayside. This type of system
presents two distinct problems: the vehicle operator must remember the
state of the signal after the vehicle has passed the block boundary, and
there is no indication of the signal level of the next block to allow
the operator to make preparatory control commands.

Many contemporary locomotive cab designs include **in-cab signals**,
which are devices in the cab that display the signal level of the block
currently occupied. While this solves the problem of remembering the
signal state of the current block, it still does not solve the preview
problem.

At true high-speed operation (speeds in excess of 124.3 mph
\[200 km/h\]), it is virtually impossible to see wayside signals in time
to take appropriate corrective action. Therefore, such operations
require some form of signal preview as part of the in-cab signal system.
In the high-speed rail simulation vehicle, the in-cab signal system is
implemented with two color-coded light bars, each containing three
lights. The bottom light bar displays the color code of the signal state
of the currently occupied block when the vehicle entered it. The top
light bar displays the color code of the signal state of the next block.

## Vehicle Operation --- Bearing Temperature Display {#vehicle-operation-bearing-temperature-display .Appendix-2}

One of the secondary gauges provided on the instrument panel of the
train simulation displays **wheel bearing temperature**. Train
operations have traditionally been concerned about detecting overheated
wheel bearings, as an overheated wheel bearing could ultimately seize
and lead to derailment. Certain train operations have installed **hot
box detectors**, which are wayside-located boxes that detect a hot
bearing as the train passes by.

The wheel bearing temperature system in the train simulation uses
sensors on each wheel to measure the temperature. The display then shows
the temperature of the hottest bearing among those that are measured. In
normal operation, the temperature will rise as the speed of the vehicle
increases, and fall to ambient temperature when the vehicle slows down.
If a wheel bearing does fail, the wheel bearing temperature gauge will
reflect the temperature of the hottest bearing. It does not, however,
indicate which bearing is at fault---the vehicle operator must stop the
train and locate the faulty bearing (usually through observation of
smoke at the wheel).

## Vehicle Operation --- Trolley Voltage Display {#vehicle-operation-trolley-voltage-display .Appendix-2}

One of the secondary gauges in the instrument panel displays the
**trolley voltage**, which is the voltage available from the power
supply grid to the traction motor controllers (nominally 1500 VDC).

The gauge is provided so that the vehicle operator can detect problems
with the power supply voltage, which will have implications on the
performance of the vehicle. Although the vehicle operator cannot take
any action to rectify such an occurrence, the vehicle operator would be
able to inform the CTC operator, via the communication channel, of the
problem. The CTC operator would then contact the appropriate personnel
in the power supply department in an effort to rectify the problem.

## Vehicle Operation --- Acceleration and Braking Performance {#vehicle-operation-acceleration-and-braking-performance .Appendix-2}

Although there are many conceptual similarities between operating a rail
vehicle and driving an automobile, the biggest difference occurs in
braking and acceleration performance. Because of the very large mass of
a rail vehicle (typically in the range of hundreds of tons), the
distances required for acceleration and braking are much larger than
might be expected. This becomes more of an issue as the vehicle speed
grows larger---the stopping distances from a speed of 186.4 mph
(300 km/h) are on the order of several kilometers.

This situation has several implications. An important safety
consideration is that the large stopping distance makes it virtually
impossible for an operator to stop in time from high speed for an
unexpected track obstruction. The only reasonable solutions to this
problem are to reduce the allowable vehicle speeds in risk-prone areas,
and to provide additional driving aids, such as obstruction warning
systems. In general, operators are not held liable for situations, which
are beyond their control.

In the simulation system, this issue is addressed by taking care that
there are no unexpected hazards that are beyond the operator's control.
Grade crossing areas are the only places where track obstructions can
occur. These obstructions take the form of highway vehicles crossing the
track. In the grade crossing areas, the civil speed limit is reduced to
62.1 mph (100 km/h). These areas include blocks 0, 1, 11, 12, and 13.
Within these areas, the vehicle operator is able to detect and react to
an obstruction at a highway grade crossing. Highway vehicles that cross
the tracks will only do so when there is sufficient distance for them to
clear the crossing before the train arrives. Under certain
circumstances, however, the highway vehicle may get stuck at the
crossing in the path of the train. By design, the point in time at which
the vehicle gets stuck will be such that the train operator has
sufficient time to detect the obstruction and stop the train before a
collision occurs.

Another implication of large braking distances is the necessity for good
judgment of braking points. Because the braking distances are so large,
proper planning of braking points is essential for a vehicle to be
stopped accurately at stations (or other stopping points). This is a
skill, which requires a great deal of practice to master, and represents
an important component of operator training programs in actual rail
operations. Such training programs typically last for a year or more.

To shorten this learning curve, graphical representations of the vehicle
performance curves are shown in Figures A-4 through A-6. Figure A-4
displays the full-throttle acceleration profile on level ground. The
speed is shown as a function of distance. From this curve, we can see
that the distance required to reach 186.4 mph (300 km/h) from a standing
stop is approximately 7.1 mi (11.5 km).

![](media/image14.emf){width="6.375in" height="3.9027777777777777in"}

> []{#__RefHeading___Toc84667738 .anchor}Figure A-4. Full-Throttle
> Acceleration Profile

In Figure A-5, the full-service braking profile is shown again for the
case of travel on level ground. From this curve, we can see that the
braking distance from 186.4 mph (300 km/h) is approximately 3.2 mph
(5.2 km), which is substantially shorter than the distance required to
achieve that speed in the first place (Figure A-4). The reason for this
difference is twofold: a) peak braking forces are generally higher than
peak traction forces, for safety reasons, and b) at higher speeds, the
resultant aerodynamic drag works against acceleration, but contributes
to deceleration forces.

Note that the braking distance from 62.1 mph (100 km/h) is just a little
larger than a half kilometer. Obstructions in the grade crossings are
visible from the vehicle for a distance of almost one
kilometer---therefore, this braking performance provides adequate
opportunity for the vehicle operator to detect and react properly to an
obstruction in a grade crossing.

![](media/image15.wmf)

> []{#__RefHeading___Toc84667739 .anchor}Figure A-5. Full-Service
> Braking Profile

The full-service braking profile (Figure A-5) can be used to estimate
appropriate braking points under manual control. When approaching West
Station, there is a civil speed restriction of 62.1 mph (100 km/h) for
two blocks (2.5 mi -- 4 km) (blocks 0 and 1, which cover the track
between mile post 4 and the station) prior to the station, to reduce
speed for grade crossing safety. Approaching East Station, there is a
similar speed restriction for one block (1.2 mi -- 2 km) (block 24,
between mile post 48 and the station), to ensure that a train does not
go through the station at full speed. In addition, there is a
speed-restricted region in blocks 11 through 13 (covering the track
between mile posts 22 and 28), for reasons of grade crossing safety.
When approaching these regions, full-service braking from full speed
(186.4 mph \[300 km/h\]) should begin 2.8 mi (4.5 km) prior to the start
of the restricted block, to ensure that the vehicle speed is at or below
the restricted speed before entering that block. When approaching the
two stations, the vehicle operator can again apply full service braking
in the last block when the vehicle is about 0.6 mi (1 km) from the
station, bringing the vehicle to a coasting speed of slightly less than
24.9 mph (40 km/h). As the vehicle passes through the entrance of the
station, the vehicle operator can again apply the brakes to stop
precisely in the station. The ideal stopping point is the position at
which the block signal board is just visible in the windscreen. If the
operator stops the vehicle too soon, the vehicle must be brought forward
to this point so that the passenger doors may be opened. The operator
may legally stop the vehicle forward of this point, as long as the exit
doorway and back wall of the station are still visible through the
windscreen.

![](media/image16.wmf)

> []{#__RefHeading___Toc84667740 .anchor}Figure A-6. Emergency Braking
> Profile

Figure A-6 shows the braking profile under emergency braking conditions.
The distance required to brake from 186.4 mph (300 km/h) under emergency
stop conditions is only about 1.05 mi (1.7 km). However, this braking
performance has a high cost---the more severe deceleration experienced
during these stopping conditions is the result of severe forces at the
wheels which can result in damaged train equipment, as well as damaged
track. In addition, in passenger service, the resultant deceleration can
cause passengers to be thrown about in the passenger compartments,
opening the possibility of injury. Emergency braking procedures are
generally considered to be a last resort. For these reasons, penalty
applications of the emergency brake triggered by the alerter, ATP, or
programmed stop systems should be avoided whenever possible.

## System Operation --- Communications {#system-operation-communications .Appendix-2}

Communications in the high-speed rail simulation system is via a
broadcast text-based system. An operator in each vehicle, as well as the
CTC operator, can enter messages through the computer keyboard. When the
message is completed (either with a carriage return or when the message
length reaches 80 characters), it is sent out over the network and
received by all other active simulation elements. Thus, everybody hears
everybody.

The protocol used for these communications aids in reducing any
confusion in the messages. Specifically, the message sender identifies
the intended recipient of the message, adds the body of the message, and
terminates with self-identification. All identification is with vehicle
identifiers (vehicle ID numbers are issued when the operator starts a
shift).

For example, the following exchange might take place between the CTC and
a train operator in vehicle E48401:

"E48401, request position, CTC."

"CTC, block 5, kmpost 11, destination East Station, E48401."

In this exchange, the CTC operator requests a position update from
operator E48401, who responded with a summary of the current vehicle
position. All of the active vehicles in the simulation heard this
exchange. The exchange format could be shortened to the following,
without any loss of information:

"E48401, req pos, CTC."

"CTC, blk 5, km 11, dest E St, E48401."

Tables A-4 and A-5 contain a summary of the most frequently used
messages and responses used in the system. Although any text is
allowable, these tables summarize the set of the most frequently used
messages and responses, in shorthand form to minimize the necessary
typing.

Most of the messages included in these tables represent typical
information, which might be conveyed between a vehicle operator and a
CTC operator in an operational rail system. In a typical rail system,
there is very limited provision for exchange of data between vehicles
and centralized control. Although this is changing as technology
progresses, voice communications over radio still represent a
significant method for transferring state information between the
vehicles and the CTC.[^3]

## System Operation --- Schedules {#system-operation-schedules .Appendix-2}

During a shift of operation, the vehicle operator is required to make
three round trips in the shuttle operation. Each round trip starts at
West Station, proceeds to East Station, reverses direction, and returns
to West Station. Each trip leg (one-way) is scheduled to take twenty
minutes. When the train reaches the destination station, the vehicle is
stopped and the doors are opened for a period of one minute, to allow
the passengers onboard to disembark. The train is then routed around the
reversing loop to change direction. The looping procedure requires
approximately seven minutes. When the train arrives at the same station
in the opposite direction, it is again stopped, and the doors are again
opened for a period of two minutes, to allow new passengers to board.
The total scheduled round trip time is one hour. A printed schedule is
provided to the operator for each shift.

+-----------------+--------------------------+--------------------------+
| []{#__RefHeadin |                          |                          |
| g___Toc90287963 |                          |                          |
| .anchor}Table   |                          |                          |
| A-4. Standard   |                          |                          |
| Communications  |                          |                          |
| Message         |                          |                          |
| Initiated by    |                          |                          |
| Vehicle         |                          |                          |
| Operator        |                          |                          |
+-----------------+--------------------------+--------------------------+
| Messages        | Message Shorthand Form   | Response From CTC        |
| Initiated by    |                          | Operator                 |
| Vehicle         |                          |                          |
| Operator        |                          |                          |
+-----------------+--------------------------+--------------------------+
| announce        | "CTC, depart             | "\<vehID\>, ack depart   |
| departure       | \<station\>, \<vehID\>"  | \<station\>, CTC"        |
+-----------------+--------------------------+--------------------------+
| announce        | "CTC, arrive             | "\<vehID\>, ack arrive   |
| arrival         | \<station\>, \<vehID\>"  | \<station\>, CTC"        |
+-----------------+--------------------------+--------------------------+
| inform of       | "CTC, \<brake \| motor\> | "\<vehID\>, ack fail,    |
| vehicle failure | fail, fixed, \<vehID\>"  | CTC"                     |
+-----------------+--------------------------+--------------------------+
| inform of       | "CTC, obstruct at        | "\<vehID\>, ack          |
| obstruction     | \<cross num\>,           | obstruct, CTC"           |
|                 | \<vehID\>"               |                          |
+-----------------+--------------------------+--------------------------+
| inform of       | "CTC, collide at \<cross | "\<vehID\>, ack collide, |
| collision       | num\>, \<vehID\>"        | CTC"                     |
+-----------------+--------------------------+--------------------------+
| request break   | "CTC, req break at       | "\<vehID\>, break req    |
|                 | \<station\>, \<vehID\>"  | accept, CTC"             |
|                 |                          |                          |
|                 |                          | "\<vehID\>, break req    |
|                 |                          | deny, CTC"               |
+-----------------+--------------------------+--------------------------+

+-----------------+--------------------------+--------------------------+
| []{#__RefHeadin |                          |                          |
| g___Toc90287964 |                          |                          |
| .anchor}Table   |                          |                          |
| A-5. Standard   |                          |                          |
| Communications  |                          |                          |
| Messages        |                          |                          |
| Initiated by    |                          |                          |
| CTC Operator    |                          |                          |
+-----------------+--------------------------+--------------------------+
| Messages        | Message Shorthand Form   | Response From Vehicle    |
| Initiated by    |                          | Operator                 |
| CTC Operator    |                          |                          |
+-----------------+--------------------------+--------------------------+
| request vehicle | "\<vehID\>, req pos,     | "CTC, km \<num\>,        |
| position        | CTC"                     | \<vehID\>"               |
+-----------------+--------------------------+--------------------------+
| request vehicle | "\<vehID\>, req veh      | "CTC, status OK,         |
| status          | status, CTC"             | \<vehID\>"               |
|                 |                          |                          |
|                 |                          | "CTC, \<brake\|motor\>   |
|                 |                          | fail, \<vehID\>"         |
|                 |                          |                          |
|                 |                          | "CTC, obstruct at        |
|                 |                          | \<cross\>, \<vehID\>"    |
|                 |                          |                          |
|                 |                          | "CTC, collide at         |
|                 |                          | \<cross\>, \<vehID\>"    |
+-----------------+--------------------------+--------------------------+
| request         | "\<vehID\>, req mode     | "CTC, man mode,          |
| automation mode | status, CTC"             | \<vehID\>"               |
| status          |                          |                          |
|                 |                          | "CTC, cruise mode,       |
|                 |                          | \<vehID\>"               |
|                 |                          |                          |
|                 |                          | "CTC, pstop mode,        |
|                 |                          | \<vehID\>"               |
|                 |                          |                          |
|                 |                          | "CTC, auto mode,         |
|                 |                          | \<vehID\>"               |
+-----------------+--------------------------+--------------------------+

Under certain circumstances, there may be deviations from the prescribed
schedule. In this case, it is the responsibility of the CTC operator to
adjust the schedules accordingly. The vehicle operator must wait for CTC
instructions before departing a station at any time that is not in
compliance with the prescribed schedule.

## System Operation --- Role of CTC Operator {#system-operation-role-of-ctc-operator .Appendix-2}

The central traffic control operator (CTC operator) is the coordinating
element in the rail system. The operator must monitor the positions and
speeds (when possible) of the vehicles in the system, and adjust
operating parameters of the system in order to achieve the system goals.
The CTC operator also represents the coordination point between the
vehicles, as well as with "outside" agencies (such as fire, police,
power, maintenance, etc.).

Given this perspective, the CTC operators have a level of jurisdiction
that is higher than the wayside signals, the operating rules, and any
other influence. In short, when there is a conflict between influences
that govern the action taken by a vehicle operator, the CTC operator is
always the highest authority. Therefore, CTC operators are supervisors,
with respect to the vehicle operators, and vehicle operators are
required to follow all directions given by the CTC operators. This
supervisory role has a higher level of responsibility than the task of
monitoring.

## System Operation --- Obstruction Hazards {#system-operation-obstruction-hazards .Appendix-2}

As mentioned in the braking performance section, the track used in the
simulation system has **highway grade crossings**. These are points in
the rail system where highway roads and rail tracks intersect. In total,
there are five grade crossings, one each located in blocks 0, 1, 11, 12,
and 13. At each grade crossing, highway vehicles (cars) can cross in
front of the train from either direction. These vehicles are visible at
over a half-kilometer distance.

In each of the blocks containing grade crossings, there is a civil speed
limit of 62.1 mph (100 km/h). This means that, regardless of the signal
level in the block, the maximum speed of a vehicle in the block is 62.1
mph (100 km/h). The ATP system is programmed to detect when these blocks
are entered, and will use this civil speed limit in its restriction
rules.

Traffic at the grade crossings arrives according to a probabilistic
process.[^4] A car will proceed across the crossing only if there is
sufficient distance to clear the crossing before the train. (In other
words, a car will not proceed if there is not enough room.) However, it
is possible for a car to become disabled as it is crossing the tracks,
which will result in an obstruction for the train. In this event, the
train operator must bring the train to a stop before the intersection.
If the train is not stopped in time, a collision will occur, which will
be indicated by a cracked windscreen.

It is important that the train operator be able to quickly assess the
crossing traffic and determine whether the train must be stopped. On one
hand, a collision is a major event, and will result in a significant
delay in operation. On the other hand, stopping the train unnecessarily
will also cause delays in service. It is up to the vehicle operator to
evaluate the situation and determine the best course of action under
these constraints.

If a collision occurs, the vehicle operator must stop the vehicle and
immediately contact the CTC operator to report the collision. In the
case of a collision, the windscreen will appear "cracked." This crack
will remain for the remainder of the shift. For each of three collisions
that might occur within a shift, the windscreen will become
progressively more "cracked."

## System Operation --- Operator Performance Requirements {#system-operation-operator-performance-requirements .Appendix-2}

In order to assure that each vehicle operator is capable of adequately
controlling the train, the performance of each operator (test subject)
is monitored throughout the test sessions. As an incentive, there is a
bonus system that provides monetary rewards for good performance. If
operator performance does not fall within certain minimum criteria,
penalties may be assessed. At the end of each experiment session, the
subject's performance is evaluated with regard to bonuses and penalties.

By decree of the Federal Code of Regulations, Number 49, Part 240, the
performance of rail vehicle operators (locomotive engineers) is
regulated such that any willful violation of speed restrictions or
signal indications is punishable with both a monetary fine and a loss of
certification (which may be permanent or temporary, depending on the
circumstances). The monetary fines are substantial, and can range from a
minimum of \$250 to a maximum of \$20,000. In short, these violations
are considered serious offenses, and are not tolerated.

Because of these regulations, speed and signal compliance are considered
key performance items. In the simulation system, violations are defined
by ATP-induced or signal-induced penalty applications of the emergency
brakes. During the road test period of the training phase, such a
violation will result in disqualification of the subject from further
participation. In this case, the subject will be paid for training
period. During the experiment phase, the first violation in a shift will
result in a penalty of 100,000 bonus points. If a second violation
occurs in the same shift, the subject will be disqualified from further
participation in the experiment. In this case, payment will cover the
sessions that have been completed to date.

In addition, willful circumvention of the vehicle safety systems, such
as the alerter system, will not be tolerated. If a subject is found to
have bypassed these safety systems, the subject will not be permitted to
complete the experimental tests. In this case, payment will cover the
sessions that have been completed to date.

Other key operator performance items include station stopping accuracy,
schedule maintenance, and response to emergency (or failure) situations.
In general, good performance in these areas will result in the award of
bonus points, which result in an increase in payment for that session.
The bonus point's schedules are shown in Tables A-6 and A-7, and the
penalty point's schedules are shown in Tables A-8 through A-10.

Table A-6 shows the bonus points that result from station stopping
performance. The stopping point is defined as the first point at which
the vehicle stops, in the vicinity of the station. The closer the stop
occurs to the designated stopping point, the more bonus points are
awarded. The bonus points are distributed to favor undershoot (i.e.,
it's preferable to stop before the designated point than after). Figure
A-7 shows this relationship in graphical form.

+-----------------------------------+-----------------------------------+
| []{#__RefHeading___Toc90287965    |                                   |
| .anchor}Table A-6. Bonus Point    |                                   |
| Schedule for Station Stopping     |                                   |
| Accuracy                          |                                   |
+-----------------------------------+-----------------------------------+
| **station stop accuracy**         | **bonus points**                  |
+-----------------------------------+-----------------------------------+
| more than 10m before stop point   | 0                                 |
|                                   |                                   |
| deviation \< -10.0 (undershoot)   |                                   |
+-----------------------------------+-----------------------------------+
| -10.0 \<= deviation \< -8.0       | +400                              |
+-----------------------------------+-----------------------------------+
| -8.0 \<= deviation \< -6.0        | +800                              |
+-----------------------------------+-----------------------------------+
| -6.0 \<= deviation \< -4.0        | +1200                             |
+-----------------------------------+-----------------------------------+
| -4.0 \<= deviation \< -2.0        | +1600                             |
+-----------------------------------+-----------------------------------+
| -2.0 \<= dev \<= +2.0             | +2000                             |
+-----------------------------------+-----------------------------------+
| +2.0 \< deviation \<= +3.0        | +1600                             |
+-----------------------------------+-----------------------------------+
| +3.0 \< deviation \<= +4.0        | +1200                             |
+-----------------------------------+-----------------------------------+
| +4.0 \< deviation \<= +5.0        | +800                              |
+-----------------------------------+-----------------------------------+
| +5.0 \< deviation \<= +6.0        | +400                              |
+-----------------------------------+-----------------------------------+
| more than 6m beyond stop point    | 0                                 |
|                                   |                                   |
| +6.0 \< deviation (overshoot)     |                                   |
+-----------------------------------+-----------------------------------+

![](media/image17.emf){width="4.736111111111111in"
height="0.6805555555555556in"}

> []{#__RefHeading___Toc84667741 .anchor}Figure A-7. Bonus Point Diagram
> for Station Stopping Accuracy

Table A-7 shows the bonus points that result from schedule accuracy.
Because there may be emergency situations that will affect schedule
maintenance (such as an obstruction or collision), the schedule is
adjusted for such occurrences. As with station stopping accuracy, the
bonus point distribution shows a preference for early arrivals over late
arrivals. Although the bias fosters early arrivals over late arrivals,
this bias is small relative to the total number of points the
participant could earn. This bias is countered by penalties for going
too fast through overspeed protection. If the engineer speeds, a penalty
brake application is applied which results in a schedule delay far in
excess of the benefits of speeding. A graphical representation is shown
in Figure A-8.

Table A-8 shows the bonus point schedule associated with failure and
emergency response. In general, you are evaluated in terms of the
response time to the failure, as well as the accuracy ("correctness") of
the first response action. The actual events used to evaluate the
accuracy depend on the specific emergency being evaluated. A summary of
these appears in the bottom portion of Table A-8.

+--------------------------------------+-------------------------------+
| []{#__RefHeading___Toc90287966       |                               |
| .anchor}Table A-7. Bonus Point       |                               |
| Schedule for Schedule Accuracy       |                               |
+--------------------------------------+-------------------------------+
| **schedule accuracy**                | **bonus points**              |
+--------------------------------------+-------------------------------+
| more than 26 secs early              | 0                             |
|                                      |                               |
| deviation \< -26.0                   |                               |
+--------------------------------------+-------------------------------+
| -26.0 \<= deviation \< -22.0         | +400                          |
+--------------------------------------+-------------------------------+
| -22.0 \<= deviation \< -18.0         | +800                          |
+--------------------------------------+-------------------------------+
| -18.0 \<= deviation \< -14.0         | +1200                         |
+--------------------------------------+-------------------------------+
| -14.0 \<= deviation \< -10.0         | +1600                         |
+--------------------------------------+-------------------------------+
| -10.0 \<= deviation \<= +8.0         | +2000                         |
+--------------------------------------+-------------------------------+
| +8.0 \< deviation \<= +12.0          | +1600                         |
+--------------------------------------+-------------------------------+
| +12.0 \< deviation \<= +16.0         | +1200                         |
+--------------------------------------+-------------------------------+
| +16.0 \< deviation \<= +20.0         | +800                          |
+--------------------------------------+-------------------------------+
| +20.0 \< deviation \<= +24.0         | +400                          |
+--------------------------------------+-------------------------------+
| more than 24 secs late               | 0                             |
|                                      |                               |
| +24.0 \< deviation                   |                               |
+--------------------------------------+-------------------------------+

![](media/image18.emf){width="3.6944444444444446in"
height="0.6666666666666666in"}

> Figure A-8. Bonus Point Diagram for Schedule Accuracy

  ----------------------------------- -----------------------------------
  []{#__RefHeading___Toc90287967      
  .anchor}Table A-8. Bonus/Penalty    
  Point Schedule for Emergency        
  Response                            

  **Emergency response time (sec)**   **bonus points**

  less than 2.0                       +1000

  more than 2.0, less than 5.0        +750

  more than 5.0, less than 10.0       +500

  more than 10.0, less than 20.0      +250

  more than 20.0                      0

  **first response accuracy,          **bonus/penalty points**
  obstruction**                       

  correct braking action              +1000

  incorrect braking action            +500

  error (other command action)        0

  safety hazard (door open command)   -1000

  **first response accuracy, brake    **bonus/penalty points**
  failure**                           

  correct action (switch brake pump)  +1000

  incorrect command action            0

  safety hazard (estop, door open     -1000
  commands)                           

  **first response accuracy, motor    **bonus/penalty points**
  failure**                           

  correct action (brake, then reset   +1000
  failed motor)                       

  partially correct action (depress   +500
  reset button for wrong motor,       
  failure to apply brakes first)      

  incorrect command action            0

  safety hazard (estop, door open     -1000
  commands)                           
  ----------------------------------- -----------------------------------

Tables A-9 and A-10 show the penalties that can be levied for poor
performance. Table A-9 identifies penalties that result from explicit
violations of the operating rules. The most significant is a penalty
application of the emergency brakes, resulting from either a speed
violation (via the ATP system) or a signal violation. Both of these are
considered serious offenses, and the resultant penalty is substantial.
The next penalty is for opening the passenger doors when the vehicle is
outside the station. This action is considered a serious compromise of
passenger safety, and is penalized accordingly. The third penalty is for
unnecessary use of the emergency brake. Use of the emergency brake takes
a heavy mechanical toll on the train systems, and results in a very
uncomfortable ride for the passengers. Gratuitous use of the emergency
brake is inappropriate, and the penalty for unnecessary use is
significant enough to outweigh any benefit that might be obtained (such
as improving the station stopping or schedule accuracy). The fourth
penalty is imposed if the operator fails to stop the vehicle within the
station. In this event, the doors must not be opened. In addition, the
vehicle operator must notify the CTC operator of the situation, and
await further instructions from the CTC operator.

+------------------------------------------+---------------------------+
| []{#__RefHeading___Toc90287968           |                           |
| .anchor}Table A-9. Penalty Point         |                           |
| Schedule for Violations                  |                           |
+------------------------------------------+---------------------------+
| **infraction**                           | **penalty points**        |
+------------------------------------------+---------------------------+
| Penalty application for speed compliance | -50,000                   |
| (ATP) or signal compliance violation     |                           |
+------------------------------------------+---------------------------+
| Passenger doors opened outside of        | -10,000                   |
| station bounds (more than 20m undershoot |                           |
| or 100m overshoot)                       |                           |
+------------------------------------------+---------------------------+
| Unnecessary application of emergency     | -5,000                    |
| brake                                    |                           |
|                                          |                           |
| (no emergency present)                   |                           |
+------------------------------------------+---------------------------+
| Station overrun                          | -2,000                    |
+------------------------------------------+---------------------------+

Table A-10 shows the penalty points that occur if there is a collision
with a highway vehicle at a grade crossing. The intent of this schedule
is to impart a sense that collisions at higher velocities are more
serious---in the event that a collision is inevitable, the operator
should do as much as possible to reduce the impact of that collision by
reducing the vehicle as much as possible.

  ------------------------------------------------ ----------------------
  []{#__RefHeading___Toc90287969 .anchor}Table     
  A-10. Penalty Point Schedule for Grade Crossing  
  Collisions                                       

  **collision impact speed (mph)**                 **penalty points**

  Between 37.3 and 62.1 mph (60 and 100 km/h)      -1000

  Between 24.9 and 37.3 mph (40 and 60 km/h)       -750

  Between 12.4 and 24.9 mph (20 and 40 km/h)       -500

  Between 0 and 12.4 mph (20 km/h)                 -250
  ------------------------------------------------ ----------------------

After the total bonus points are computed for a shift, the bonus points
are converted into a pay bonus, at the rate of one dollar for each ten
thousand points. There are a total of eleven station stops per shift,
for a maximum possible 44,000 points per shift for station stopping
performance. Because the number of failures and obstructions will vary
from shift to shift, it is not possible to determine beforehand the
maximum possible bonus points that are available. However, in most
cases, there will be sufficient opportunity for an excess of 50,000
bonus points, which will yield an equivalent pay rate in excess of \$10
per hour.

# APPENDIX B. WRITTEN REVIEW QUIZ

Instructions: For each question, circle the letter of the answer you
feel best answers the question.

1\. "Kilometer posts" are located where?

> a\) on the wayside, at tenth-kilometer intervals
>
> b\) on the vehicle instrument panel
>
> c\) on the wayside, at kilometer intervals
>
> d\) on a monitor screen in the CTC operations center

2\. Which of the following is considered an automatic mode?

> a\) programmed stop
>
> b\) emergency stop
>
> c\) ATP warning
>
> d\) alerter warning

3.  If the signal level of the upcoming block is full yellow (YYY), what
    is the speed limit in

    that block?

> a\) 15 km/h (9.3 mph)
>
> b\) 150 km/h (93.2 mph)
>
> c\) 80 km/h (49.7 mph)
>
> d\) 230 km/h (142.9 mph)

4\. What is the expected one-way travel time between East Station and
West Station?

> a\) 5 minutes
>
> b\) 20 minutes
>
> c\) 15 minutes
>
> d\) 25 minutes

5\. How many signal levels are used?

> a\) one
>
> b\) seven
>
> c\) four
>
> d\) five

6\. How many control modes are available on the train?

> a\) none
>
> b\) four
>
> c\) three
>
> d\) ten

7\. When full service braking is applied, what is the typical tank
pressure?

> a\) 1000 psi
>
> b\) 100 psi
>
> c\) 0 psi
>
> d\) 22 psi

8\. Where are block signals located?

> a\) at the entrance to every block
>
> b\) in the middle of every block
>
> c\) every 50 m (164 ft)
>
> d\) on the back of the preceding train

9\. What is the expected distance to accelerate to 300 km/h from a
standing stop on level

ground?

> a\) 11.5 km (7.1 mi)
>
> b\) 21.2 km (13.2 mi)
>
> c\) 4.5 km (2.8 mi)
>
> d\) 5.7 km (3.5 mi)

10\. Which category best describes the type of system being operated?

> a\) shuttle service
>
> b\) subway
>
> c\) commuter rail
>
> d\) long-haul freight

11\. There are four electric traction motors. How many circuit breakers
in total are used to

protect these traction motors?

> a\) eight
>
> b\) four
>
> c\) one
>
> d\) none

12\. How is the programmed stop mode disabled?

> a\) by manually applying the brakes
>
> b\) by depressing the cruise control enable button
>
> c\) by depressing the programmed stop enable button
>
> d\) by waiting until the vehicle comes to a stop

13\. During system operation, how many trains are simultaneously in use?

> a\) four
>
> b\) one
>
> c\) ten
>
> d\) two

14\. In autopilot mode, the control system maintains the proper speed
through which control

mechanism?

> a\) thrust only
>
> b\) braking only
>
> c\) both thrust and braking
>
> d\) magnetic levitation

15\. How is the cruise control mode enabled?

> a\) by depressing the cruise control button while braking to the
> desired speed
>
> b\) by depressing autopilot and cruise control buttons simultaneously
>
> c\) by holding the vehicle at a steady speed under manual control
>
> d\) by depressing the cruise control button while traveling at the
> desired speed

16\. What is the relative status of the CTC operator, from the
perspective of a train operator?

> a\) supervisor
>
> b\) subordinate
>
> c\) monitor
>
> d\) peer

17\. If the vehicle speed exceeds the maximum allowable speed by more
than 15 km/h, the

ATP system does what?

> a\) applies the emergency brake
>
> b\) applies more thrust
>
> c\) limits the effectiveness of manual thrust commands
>
> d\) applies the service brake

18\. What is the purpose of the block signal system?

> a\) for vehicle operator to determine the number of vehicles allowed
> in the block
>
> b\) for vehicle operator to determine the maximum allowable speed in
> the block
>
> c\) give vehicle operators something to do
>
> d\) for vehicle operator to determine the number of passengers allowed
> on board

19\. In a block signaling system, how many trains are allowed to occupy
a single block at the

same time?

> a\) two
>
> b\) four
>
> c\) none
>
> d\) one

20\. How many different braking modes are available to the vehicle
operator?

> a\) one
>
> b\) three
>
> c\) five
>
> d\) two
>
> 21\. If the vehicle operator moves the vehicle when the doors are
> still open, what happens?
>
> a\) the motor circuit breakers are tripped
>
> b\) the passengers are warned over the intercom
>
> c\) the emergency brakes are applied
>
> d\) the doors close automatically

22\. What is the expected stopping distance from 300 km/h (186.4 mph) to
100 km/h

(62.1 mph) under full-service braking on level ground?

> a\) 21.2 km (13.2 mi)
>
> b\) 11.5 km (7.1 mi)
>
> c\) 4.5 km (2.8 mi)
>
> d\) 5.7 km (3.5 mi)

23\. What warning does the alerter system give the vehicle operator
before a penalty

application is imposed?

> a\) chime only, for 5 seconds
>
> b\) electric shock through the seat, for 5 seconds
>
> c\) flashing light only, for 15 seconds
>
> d\) flashing lights and chime, for 10 seconds

24\. How does the vehicle operator know the speed of the train?

> a\) from the CTC operator
>
> b\) from the speedometer, on the vehicle instrument panel
>
> c\) from the brake pressure gauge, on the vehicle instrument panel
>
> d\) from the block signaling system

25\. Where are CTC operators located?

> a\) in a maintenance shed
>
> b\) in small booths along the wayside
>
> c\) in a centralized operations center
>
> d\) in the last car of each train

#   {#section-1 .unnumbered}

# APPENDIX C. TRAIN SCHEDULE

00:05:00 Depart West Station

00:23:30 Arrive East Station --- discharge passengers

00:26:00 Depart East Station --- loop around

00:33:00 Arrive East Station --- board passengers

00:35:00 Depart East Station

00:53:00 Arrive West Station --- discharge passengers

00:56:00 Depart West Station --- loop around

01:03:00 Arrive West Station --- board passengers

01:05:00 Depart West Station

01:23:30 Arrive East Station --- discharge passengers

01:26:00 Depart East Station --- loop around

01:33:00 Arrive East Station --- board passengers

01:35:00 Depart East Station

01:53:00 Arrive West Station --- discharge passengers

01:56:00 Depart West Station --- loop around

02:03:00 Arrive West Station --- board passengers

02:05:00 Depart West Station

02:23:30 Arrive East Station --- discharge passengers

02:26:00 Depart East Station --- loop around

02:33:00 Arrive East Station --- board passengers

02:35:00 Depart East Station

02:53:00 Arrive West Station --- discharge passengers

# APPENDIX D. EXIT QUESTIONNAIRE

Please answer the following questions.

1.  Rate the levels of automation in order of preference (use "1" for
    the automation level you liked the most, "3" for the automation
    level you liked the least)?

> \_\_ full automation (autopilot)
>
> \_\_ partial automation (cruise control and programmed stop)
>
> \_\_ no automation (manual control)

2.  Rate the levels of automation according to level of "awareness" (use
    "1" for the

> automation level in which you felt the most aware, "3" for the
> automation level in
>
> which you felt the least aware)?
>
> \_\_ full automation (autopilot)
>
> \_\_ partial automation (cruise control and programmed stop)
>
> \_\_ no automation (manual control)
>
> 3\. Do you feel that the training process provided adequate
> preparation for the test task?
>
> \_\_ yes \_\_ no
>
> 4\. Any other comments? Critical comments are appreciated.

# APPENDIX E. INTERACTIVE TRAINING PROCEDURE

The subject training takes place over two 3-hour sessions. Prior to the
first session, the subjects are instructed to review the training
tutorial material, in preparation for a written quiz. The first training
session should begin with the subject completing this written review
quiz. This quiz consists of 25 multiple choice questions, and is
intended to be on the level of a written quiz given by a state driver
licensing department. The quiz is used to provide motivation for the
subjects to review the tutorial material, and to allow the instructor to
identify any weakness areas prior to the interactive training.

The first session continues with the interactive segment. The instructor
briefly introduces the subject to the CTC display, and explains the role
of the CTC operator with respect to overall system operation. The
instructor then introduces the subject to the train simulator, and
reviews the basics of operation in the following order:

1\. Identify the OTW viewport and all visual cues that appear in this
display

2\. Identify the instrument panel display and all of the instruments
that appear on that display

3\. Identify the combined control lever

4\. Identify the keyboard controls

5\. Have the subject move the train slowly out of the station, noting
behavior of the head-up

display

6\. Test operation of the alerter system

7\. Test operation of the ATP system

8\. Make note of grade crossing details, mile posts, block signals,
landmarks

9\. Describe operation of cruise control, test

10\. Describe operation of autopilot, test

11\. Describe operation of programmed stop, test, and

12\. Describe procedure for stopping in station, coach through the
procedure.

The first training session continues with two round trips. In effect,
this is the first opportunity for the subject to experience solo
operation, with the instructor acting as CTC controller. On the first,
the goal is to familiarize the subject with use of the automation modes,
as well as the operating schedule and interaction with the CTC operator.
The subject is instructed to use manual control for the first trip leg,
cruise control and programmed stop in the loop, and autopilot on the
return trip leg. On the second round trip, the goal is to familiarize
the subject with the failure modes. The subject is instructed to use
manual control for the entire trip, and experiences a series of expected
failures that require operator response.

The second training session represents a combination practice session
and road test. The subjects are instructed to treat this session as a
real shift of operation. They are to operate the train in manual mode,
and are to adhere to the schedule to the best of their abilities. The
first round trip (i.e., the first four station stops) is a practice
period, and the remaining time is a road test. Their proficiency is
judged on the basis of their station stopping accuracy.

# REFERENCES

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Control of High-Speed Trains: Experiments and Model. Ph.D. Thesis,
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Guided Ground Transportation Systems, Phase II: Design and Evaluation of
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Transportation, Federal Railroad Administration.

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and Research Needs*. Washington, DC: U.S. Department of Transportation,
Federal Railroad Administration.

Endsley, M. (1987). SAGAT: A methodology for the measurement of
situation awareness (NOR DOC 87-83). Hawthorne, CA: Northrup Corp.

Endsley, M. (1988). Situation Awareness Global Assessment Technique
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Conference. New York: IEEE.

Endsley, M. (1995). Toward a Theory of Situation Awareness in Dynamic
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Gaba, David M., Howard, Steven K., and Small, Stephen D. (1995).
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> pp. 5-19.

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[^1]: Locomotive engineers normally look out the side window to obtain
    information to brake as a station is approached. The part-task
    simulator had no window to see the boundaries of the station, so the
    information they were missing was given in the head-up display.

[^2]: There is difficulty using detailed statistical analysis on this
    type of data because of the subjective nature of the question and
    response. One possible approach is to assign values to each level
    (e.g., "high"=3, "medium"=2, and "low"=1), then tally up and compare
    the results. Using these numbers, it could be concluded that
    subjective situation awareness strongly favored manual control (with
    a score of 33, versus 24 for partial automation, and 15 for full
    automation), while the subject preferences show a slight favor of
    full automation (with a score of 27, versus 23 for partial
    automation and 22 for manual control). However, the assignment of
    numerical values to the ordinal rating is arbitrary, and a little
    number manipulation could alter those results. Thus, the authors are
    hesitant to use detailed analysis for this purpose.

[^3]: A complex keyboard was used for communications instead of the
    radio so that the communications could be easily recorded for
    analysis following an experiment.

[^4]: There wasn't a good way to model the motorist's motivation and the
    frequency with which the motorist crosses in front of the train. We
    addressed this problem by making a simplifying assumption and
    modeling the outcome of the motorist's behavior based upon a
    probabilistic process. This probabilistic process was intended to
    cover all the cases in which the motorist may or may not cross in
    front of the train.