+-----------+----------------------------------------------------------+
| ![](m     | **Supporting Railroad Roadway Worker Communications with |
| edia/imag | a Wireless Handheld Computer: Volume 1:\                 |
| e1.wmf){w | Usability for the Roadway Worker**                       |
| 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-04/13.1    | > Final Report     | This document is       |
|                        | >                  | available to the       |
|                        | > October 2004     |                        |
|                        |                    | 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 |   |                 |
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|                |     |          |           | v |   |                 |
|                |     |          |           | e |   |                 |
|                |     |          |           | d |   |                 |
|                |     |          |           | * |   |                 |
|                |     |          |           |   |   |                 |
|                |     |          |           | * |   |                 |
|                |     |          |           | O |   |                 |
|                |     |          |           | M |   |                 |
|                |     |          |           | B |   |                 |
|                |     |          |           | N |   |                 |
|                |     |          |           | o |   |                 |
|                |     |          |           | . |   |                 |
|                |     |          |           | 0 |   |                 |
|                |     |          |           | 7 |   |                 |
|                |     |          |           | 0 |   |                 |
|                |     |          |           | 4 |   |                 |
|                |     |          |           | - |   |                 |
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|                |     |          |           | 1 |   |                 |
|                |     |          |           | 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 other      |     |          |           |   |   |                 |
| aspect of this |     |          |           |   |   |                 |
| collection of  |     |          |           |   |   |                 |
| information,   |     |          |           |   |   |                 |
| including      |     |          |           |   |   |                 |
| suggestions    |     |          |           |   |   |                 |
| for reducing   |     |          |           |   |   |                 |
| this burden,   |     |          |           |   |   |                 |
| to Washington  |     |          |           |   |   |                 |
| Headquarters   |     |          |           |   |   |                 |
| Services,      |     |          |           |   |   |                 |
| Directorate    |     |          |           |   |   |                 |
| for            |     |          |           |   |   |                 |
| Information    |     |          |           |   |   |                 |
| Operations and |     |          |           |   |   |                 |
| Reports, 1215  |     |          |           |   |   |                 |
| Jefferson      |     |          |           |   |   |                 |
| Davis Highway, |     |          |           |   |   |                 |
| Suite 1204,    |     |          |           |   |   |                 |
| Arlington, VA  |     |          |           |   |   |                 |
| 22202-4302,    |     |          |           |   |   |                 |
| and to the     |     |          |           |   |   |                 |
| Office of      |     |          |           |   |   |                 |
| Management and |     |          |           |   |   |                 |
| Budget,        |     |          |           |   |   |                 |
| Paperwork      |     |          |           |   |   |                 |
| Reduction      |     |          |           |   |   |                 |
| Project        |     |          |           |   |   |                 |
| (0704-0188),   |     |          |           |   |   |                 |
| Washington, DC |     |          |           |   |   |                 |
| 20503.         |     |          |           |   |   |                 |
+----------------+-----+----------+-----------+---+---+-----------------+
| 1\. AGENCY USE |     | 2\.      |           | 3 |   |                 |
| ONLY (Leave    |     | REPORT   |           | \ |   |                 |
| blank)         |     | DATE     |           | . |   |                 |
|                |     |          |           | R |   |                 |
|                |     | October  |           | E |   |                 |
|                |     | 2004     |           | P |   |                 |
|                |     |          |           | O |   |                 |
|                |     |          |           | R |   |                 |
|                |     |          |           | T |   |                 |
|                |     |          |           | T |   |                 |
|                |     |          |           | Y |   |                 |
|                |     |          |           | P |   |                 |
|                |     |          |           | E |   |                 |
|                |     |          |           | A |   |                 |
|                |     |          |           | N |   |                 |
|                |     |          |           | D |   |                 |
|                |     |          |           | D |   |                 |
|                |     |          |           | A |   |                 |
|                |     |          |           | T |   |                 |
|                |     |          |           | E |   |                 |
|                |     |          |           | S |   |                 |
|                |     |          |           | C |   |                 |
|                |     |          |           | O |   |                 |
|                |     |          |           | V |   |                 |
|                |     |          |           | E |   |                 |
|                |     |          |           | R |   |                 |
|                |     |          |           | E |   |                 |
|                |     |          |           | D |   |                 |
|                |     |          |           |   |   |                 |
|                |     |          |           | F |   |                 |
|                |     |          |           | i |   |                 |
|                |     |          |           | n |   |                 |
|                |     |          |           | a |   |                 |
|                |     |          |           | l |   |                 |
|                |     |          |           | R |   |                 |
|                |     |          |           | e |   |                 |
|                |     |          |           | p |   |                 |
|                |     |          |           | o |   |                 |
|                |     |          |           | r |   |                 |
|                |     |          |           | t |   |                 |
|                |     |          |           |   |   |                 |
|                |     |          |           | S |   |                 |
|                |     |          |           | e |   |                 |
|                |     |          |           | p |   |                 |
|                |     |          |           | t |   |                 |
|                |     |          |           | e |   |                 |
|                |     |          |           | m |   |                 |
|                |     |          |           | b |   |                 |
|                |     |          |           | e |   |                 |
|                |     |          |           | r |   |                 |
|                |     |          |           | 1 |   |                 |
|                |     |          |           | 9 |   |                 |
|                |     |          |           | 9 |   |                 |
|                |     |          |           | 8 |   |                 |
|                |     |          |           | - |   |                 |
|                |     |          |           | O |   |                 |
|                |     |          |           | c |   |                 |
|                |     |          |           | t |   |                 |
|                |     |          |           | o |   |                 |
|                |     |          |           | b |   |                 |
|                |     |          |           | e |   |                 |
|                |     |          |           | r |   |                 |
|                |     |          |           | 1 |   |                 |
|                |     |          |           | 9 |   |                 |
|                |     |          |           | 9 |   |                 |
|                |     |          |           | 9 |   |                 |
+----------------+-----+----------+-----------+---+---+-----------------+
| 4\. TITLE AND  |     |          |           |   | 5 |                 |
| SUBTITLE       |     |          |           |   | \ |                 |
|                |     |          |           |   | . |                 |
| Supporting     |     |          |           |   | F |                 |
| Railroad       |     |          |           |   | U |                 |
| Roadway Worker |     |          |           |   | N |                 |
| Communications |     |          |           |   | D |                 |
| with a         |     |          |           |   | I |                 |
| Wireless       |     |          |           |   | N |                 |
| Handheld       |     |          |           |   | G |                 |
| Computer:      |     |          |           |   | N |                 |
| Volume 1:      |     |          |           |   | U |                 |
| Usability for  |     |          |           |   | M |                 |
| the Roadway    |     |          |           |   | B |                 |
| Worker         |     |          |           |   | E |                 |
|                |     |          |           |   | R |                 |
|                |     |          |           |   | S |                 |
|                |     |          |           |   |   |                 |
|                |     |          |           |   | R |                 |
|                |     |          |           |   | 2 |                 |
|                |     |          |           |   | 1 |                 |
|                |     |          |           |   | 0 |                 |
|                |     |          |           |   | 3 |                 |
|                |     |          |           |   | / |                 |
|                |     |          |           |   | R |                 |
|                |     |          |           |   | R |                 |
|                |     |          |           |   | 2 |                 |
|                |     |          |           |   | 0 |                 |
|                |     |          |           |   | 4 |                 |
+----------------+-----+----------+-----------+---+---+-----------------+
| 6\. AUTHOR(S)  |     |          |           |   |   |                 |
|                |     |          |           |   |   |                 |
| Nicolas Oriol, |     |          |           |   |   |                 |
| Thomas         |     |          |           |   |   |                 |
| Sheridan, and  |     |          |           |   |   |                 |
| Jordan Multer  |     |          |           |   |   |                 |
+----------------+-----+----------+-----------+---+---+-----------------+
| 7\. PERFORMING |     |          |           |   | 8 |                 |
| ORGANIZATION   |     |          |           |   | \ |                 |
| NAME(S) AND    |     |          |           |   | . |                 |
| ADDRESS(ES)    |     |          |           |   | P |                 |
|                |     |          |           |   | E |                 |
| U.S.           |     |          |           |   | R |                 |
| Department of  |     |          |           |   | F |                 |
| Transportation |     |          |           |   | O |                 |
|                |     |          |           |   | R |                 |
| Research and   |     |          |           |   | M |                 |
| Special        |     |          |           |   | I |                 |
| Programs       |     |          |           |   | N |                 |
| Administration |     |          |           |   | G |                 |
|                |     |          |           |   | O |                 |
| John A. Volpe  |     |          |           |   | R |                 |
| National       |     |          |           |   | G |                 |
| Transportation |     |          |           |   | A |                 |
| Systems Center |     |          |           |   | N |                 |
|                |     |          |           |   | I |                 |
| Cambridge, MA  |     |          |           |   | Z |                 |
| 02142-1093     |     |          |           |   | A |                 |
|                |     |          |           |   | T |                 |
|                |     |          |           |   | I |                 |
|                |     |          |           |   | O |                 |
|                |     |          |           |   | N |                 |
|                |     |          |           |   | R |                 |
|                |     |          |           |   | E |                 |
|                |     |          |           |   | P |                 |
|                |     |          |           |   | O |                 |
|                |     |          |           |   | R |                 |
|                |     |          |           |   | T |                 |
|                |     |          |           |   | N |                 |
|                |     |          |           |   | U |                 |
|                |     |          |           |   | M |                 |
|                |     |          |           |   | B |                 |
|                |     |          |           |   | E |                 |
|                |     |          |           |   | R |                 |
|                |     |          |           |   |   |                 |
|                |     |          |           |   | # |                 |
|                |     |          |           |   | # |                 |
|                |     |          |           |   | # |                 |
|                |     |          |           |   |   |                 |
|                |     |          |           |   |   |                 |
|                |     |          |           |   | { |                 |
|                |     |          |           |   | # |                 |
|                |     |          |           |   | s |                 |
|                |     |          |           |   | e |                 |
|                |     |          |           |   | c |                 |
|                |     |          |           |   | t |                 |
|                |     |          |           |   | i |                 |
|                |     |          |           |   | o |                 |
|                |     |          |           |   | n |                 |
|                |     |          |           |   |   |                 |
|                |     |          |           |   | . |                 |
|                |     |          |           |   | u |                 |
|                |     |          |           |   | n |                 |
|                |     |          |           |   | n |                 |
|                |     |          |           |   | u |                 |
|                |     |          |           |   | m |                 |
|                |     |          |           |   | b |                 |
|                |     |          |           |   | e |                 |
|                |     |          |           |   | r |                 |
|                |     |          |           |   | e |                 |
|                |     |          |           |   | d |                 |
|                |     |          |           |   | } |                 |
|                |     |          |           |   |   |                 |
|                |     |          |           |   | D |                 |
|                |     |          |           |   | O |                 |
|                |     |          |           |   | T |                 |
|                |     |          |           |   | - |                 |
|                |     |          |           |   | V |                 |
|                |     |          |           |   | N |                 |
|                |     |          |           |   | T |                 |
|                |     |          |           |   | S |                 |
|                |     |          |           |   | C |                 |
|                |     |          |           |   | - |                 |
|                |     |          |           |   | F |                 |
|                |     |          |           |   | R |                 |
|                |     |          |           |   | A |                 |
|                |     |          |           |   | - |                 |
|                |     |          |           |   | 0 |                 |
|                |     |          |           |   | 4 |                 |
|                |     |          |           |   | - |                 |
|                |     |          |           |   | 0 |                 |
|                |     |          |           |   | 2 |                 |
+----------------+-----+----------+-----------+---+---+-----------------+
| 9\.            |     |          |           |   | 1 |                 |
| SPONSOR        |     |          |           |   | 0 |                 |
| ING/MONITORING |     |          |           |   | \ |                 |
| AGENCY NAME(S) |     |          |           |   | . |                 |
| AND            |     |          |           |   | S |                 |
| ADDRESS(ES)    |     |          |           |   | P |                 |
|                |     |          |           |   | O |                 |
| U.S.           |     |          |           |   | N |                 |
| Department of  |     |          |           |   | S |                 |
| Transportation |     |          |           |   | O |                 |
|                |     |          |           |   | R |                 |
| Federal        |     |          |           |   | I |                 |
| Railroad       |     |          |           |   | N |                 |
| Administration |     |          |           |   | G |                 |
|                |     |          |           |   | / |                 |
| Office of      |     |          |           |   | M |                 |
| Research and   |     |          |           |   | O |                 |
| Development    |     |          |           |   | N |                 |
|                |     |          |           |   | I |                 |
| 1120 Vermont   |     |          |           |   | T |                 |
| Avenue, NW     |     |          |           |   | O |                 |
| Mail Stop 20   |     |          |           |   | R |                 |
|                |     |          |           |   | I |                 |
| Washington,    |     |          |           |   | N |                 |
| DC. 20590      |     |          |           |   | 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 |                 |
|                |     |          |           |   | 3 |                 |
|                |     |          |           |   | . |                 |
|                |     |          |           |   | 1 |                 |
+----------------+-----+----------+-----------+---+---+-----------------+
| 11\.           |     |          |           |   |   |                 |
| SUPPLEMENTARY  |     |          |           |   |   |                 |
| NOTES          |     |          |           |   |   |                 |
+----------------+-----+----------+-----------+---+---+-----------------+
| 12a.           |     |          |           |   | 1 |                 |
| DISTRIBUTIO    |     |          |           |   | 2 |                 |
| N/AVAILABILITY |     |          |           |   | b |                 |
| STATEMENT      |     |          |           |   | . |                 |
|                |     |          |           |   | D |                 |
| This document  |     |          |           |   | I |                 |
| is available   |     |          |           |   | S |                 |
| to the public  |     |          |           |   | T |                 |
| through the    |     |          |           |   | R |                 |
| National       |     |          |           |   | I |                 |
| Technical      |     |          |           |   | B |                 |
| Information    |     |          |           |   | U |                 |
| Service,       |     |          |           |   | T |                 |
| Springfield,   |     |          |           |   | I |                 |
| Virginia       |     |          |           |   | O |                 |
| 22161. This    |     |          |           |   | N |                 |
| document is    |     |          |           |   | C |                 |
| also available |     |          |           |   | O |                 |
| on the FRA     |     |          |           |   | D |                 |
| website at     |     |          |           |   | E |                 |
| ww             |     |          |           |   |   |                 |
| w.fra.dot.gov. |     |          |           |   |   |                 |
+----------------+-----+----------+-----------+---+---+-----------------+
| 13\. ABSTRACT  |     |          |           |   |   |                 |
| (Maximum 200   |     |          |           |   |   |                 |
| words)         |     |          |           |   |   |                 |
|                |     |          |           |   |   |                 |
| Communications |     |          |           |   |   |                 |
| in current     |     |          |           |   |   |                 |
| railroad       |     |          |           |   |   |                 |
| operations     |     |          |           |   |   |                 |
| rely heavily   |     |          |           |   |   |                 |
| on voice       |     |          |           |   |   |                 |
| c              |     |          |           |   |   |                 |
| ommunications. |     |          |           |   |   |                 |
| Radio          |     |          |           |   |   |                 |
| congestion     |     |          |           |   |   |                 |
| impairs        |     |          |           |   |   |                 |
| roadway        |     |          |           |   |   |                 |
| workers'       |     |          |           |   |   |                 |
| ability to     |     |          |           |   |   |                 |
| communicate    |     |          |           |   |   |                 |
| effectively    |     |          |           |   |   |                 |
| with           |     |          |           |   |   |                 |
| dispatchers at |     |          |           |   |   |                 |
| the Central    |     |          |           |   |   |                 |
| Traffic        |     |          |           |   |   |                 |
| Control Center |     |          |           |   |   |                 |
| and has        |     |          |           |   |   |                 |
| adverse        |     |          |           |   |   |                 |
| consequences   |     |          |           |   |   |                 |
| for the safety |     |          |           |   |   |                 |
| and efficiency |     |          |           |   |   |                 |
| of railroad    |     |          |           |   |   |                 |
| operations.    |     |          |           |   |   |                 |
|                |     |          |           |   |   |                 |
| A prototype    |     |          |           |   |   |                 |
| communications |     |          |           |   |   |                 |
| device was     |     |          |           |   |   |                 |
| developed for  |     |          |           |   |   |                 |
| roadway        |     |          |           |   |   |                 |
| workers to     |     |          |           |   |   |                 |
| request train  |     |          |           |   |   |                 |
| and territory  |     |          |           |   |   |                 |
| information    |     |          |           |   |   |                 |
| and to request |     |          |           |   |   |                 |
| track          |     |          |           |   |   |                 |
| protection     |     |          |           |   |   |                 |
| from the       |     |          |           |   |   |                 |
| dispatcher.    |     |          |           |   |   |                 |
| The device     |     |          |           |   |   |                 |
| uses a         |     |          |           |   |   |                 |
| wireless data  |     |          |           |   |   |                 |
| link to send   |     |          |           |   |   |                 |
| and receive    |     |          |           |   |   |                 |
| information in |     |          |           |   |   |                 |
| digital form.  |     |          |           |   |   |                 |
| The data link  |     |          |           |   |   |                 |
| device was     |     |          |           |   |   |                 |
| designed to    |     |          |           |   |   |                 |
| obtain         |     |          |           |   |   |                 |
| real-time      |     |          |           |   |   |                 |
| information    |     |          |           |   |   |                 |
| about train    |     |          |           |   |   |                 |
| location       |     |          |           |   |   |                 |
| without        |     |          |           |   |   |                 |
| assistance     |     |          |           |   |   |                 |
| from the       |     |          |           |   |   |                 |
| dispatcher.    |     |          |           |   |   |                 |
|                |     |          |           |   |   |                 |
| The report     |     |          |           |   |   |                 |
| describes the  |     |          |           |   |   |                 |
| development of |     |          |           |   |   |                 |
| this device    |     |          |           |   |   |                 |
| and a          |     |          |           |   |   |                 |
| usability      |     |          |           |   |   |                 |
| evaluation to  |     |          |           |   |   |                 |
| identify       |     |          |           |   |   |                 |
| safety and     |     |          |           |   |   |                 |
| productivity   |     |          |           |   |   |                 |
| issues that    |     |          |           |   |   |                 |
| must be        |     |          |           |   |   |                 |
| addressed for  |     |          |           |   |   |                 |
| successful     |     |          |           |   |   |                 |
| i              |     |          |           |   |   |                 |
| mplementation. |     |          |           |   |   |                 |
+----------------+-----+----------+-----------+---+---+-----------------+
| 14\. SUBJECT   |     |          |           |   |   | 15\. NUMBER OF  |
| TERMS          |     |          |           |   |   | PAGES           |
|                |     |          |           |   |   |                 |
| cognitive task |     |          |           |   |   | 76              |
| analysis, data |     |          |           |   |   |                 |
| link           |     |          |           |   |   |                 |
| c              |     |          |           |   |   |                 |
| ommunications, |     |          |           |   |   |                 |
| de             |     |          |           |   |   |                 |
| cision-making, |     |          |           |   |   |                 |
| intelligent    |     |          |           |   |   |                 |
| railroad       |     |          |           |   |   |                 |
| systems,       |     |          |           |   |   |                 |
| railroad       |     |          |           |   |   |                 |
| dispatcher,    |     |          |           |   |   |                 |
| roadway        |     |          |           |   |   |                 |
| worker, track  |     |          |           |   |   |                 |
| allocation,    |     |          |           |   |   |                 |
| train routing, |     |          |           |   |   |                 |
| usability      |     |          |           |   |   |                 |
+----------------+-----+----------+-----------+---+---+-----------------+
|                |     |          |           |   |   | 16\. PRICE CODE |
+----------------+-----+----------+-----------+---+---+-----------------+
| 17\. SECURITY  | 1   |          | 19\.      |   |   | 20\. LIMITATION |
| C              | 8\. |          | SECURITY  |   |   | OF ABSTRACT     |
| LASSIFICATION\ | SE  |          | CLASSI    |   |   |                 |
| OF REPORT      | CUR |          | FICATION\ |   |   | ####  {#section |
|                | ITY |          | OF        |   |   | -1 .unnumbered} |
| Unclassified   | CLA |          | ABSTRACT  |   |   |                 |
|                | SSI |          |           |   |   |                 |
|                | FIC |          | Unc       |   |   |                 |
|                | ATI |          | lassified |   |   |                 |
|                | ON\ |          |           |   |   |                 |
|                | OF  |          |           |   |   |                 |
|                | T   |          |           |   |   |                 |
|                | HIS |          |           |   |   |                 |
|                | P   |          |           |   |   |                 |
|                | AGE |          |           |   |   |                 |
|                |     |          |           |   |   |                 |
|                | Unc |          |           |   |   |                 |
|                | las |          |           |   |   |                 |
|                | sif |          |           |   |   |                 |
|                | ied |          |           |   |   |                 |
+----------------+-----+----------+-----------+---+---+-----------------+

NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI
Std. 239-18298-102

METRIC/ENGLISH CONVERSION FACTORS

<table style="width:100%;">
<colgroup>
<col style="width: 23%" />
<col style="width: 1%" />
<col style="width: 0%" />
<col style="width: 23%" />
<col style="width: 0%" />
<col style="width: 23%" />
<col style="width: 0%" />
<col style="width: 1%" />
<col style="width: 0%" />
<col style="width: 0%" />
<col style="width: 24%" />
</colgroup>
<thead>
<tr class="header">
<th colspan="5"><strong>ENGLISH TO METRIC</strong></th>
<th colspan="6"><strong>METRIC TO ENGLISH</strong></th>
</tr>
<tr class="odd">
<th colspan="5"><strong>LENGTH (APPROXIMATE)</strong></th>
<th colspan="6"><strong>LENGTH (APPROXIMATE)</strong></th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td><strong>1 inch (in)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>2.5 centimeters (cm)</strong></td>
<td colspan="2"><strong>1 millimeter (mm)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>0.04 inch (in)</strong></td>
</tr>
<tr class="even">
<td><strong>1 foot (ft)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>30 centimeters (cm)</strong></td>
<td colspan="2"><strong>1 centimeter (cm)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>0.4 inch (in)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 yard (yd)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>0.9 meter (m)</strong></td>
<td colspan="2"><strong>1 meter (m)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>3.3 feet (ft)</strong></td>
</tr>
<tr class="even">
<td><strong>1 mile (mi)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>1.6 kilometers (km)</strong></td>
<td colspan="2"><strong>1 meter (m)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>1.1 yards (yd)</strong></td>
</tr>
<tr class="odd">
<td></td>
<td></td>
<td colspan="2"></td>
<td colspan="2"><strong>1 kilometer (km)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>0.6 mile (mi)</strong></td>
</tr>
<tr class="even">
<td colspan="5"><strong>AREA (APPROXIMATE)</strong></td>
<td colspan="6"><strong>AREA (APPROXIMATE)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 square inch (sq in, in<sup>2</sup>)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>6.5 square centimeters
(cm<sup>2</sup>)</strong></td>
<td colspan="2"><strong>1 square centimeter
(cm<sup>2</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>0.16 square inch (sq in,
in<sup>2</sup>)</strong></td>
</tr>
<tr class="even">
<td><strong>1 square foot (sq ft, ft<sup>2</sup>)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>0.09 square meter (m<sup>2</sup>)</strong></td>
<td colspan="2"><strong>1 square meter (m<sup>2</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>1.2 square yards (sq yd,
yd<sup>2</sup>)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 square yard (sq yd, yd<sup>2</sup>)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>0.8 square meter (m<sup>2</sup>)</strong></td>
<td colspan="2"><strong>1 square kilometer
(km<sup>2</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>0.4 square mile (sq mi,
mi<sup>2</sup>)</strong></td>
</tr>
<tr class="even">
<td><strong>1 square mile (sq mi, mi<sup>2</sup>)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>2.6 square kilometers
(km<sup>2</sup>)</strong></td>
<td colspan="2"><strong>10,000 square meters
(m<sup>2</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>1 hectare (ha) = 2.5 acres</strong></td>
</tr>
<tr class="odd">
<td><strong>1 acre = 0.4 hectare (he)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>4,000 square meters
(m<sup>2</sup>)</strong></td>
<td colspan="2"></td>
<td colspan="3"></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td colspan="5"><strong>MASS - WEIGHT (APPROXIMATE)</strong></td>
<td colspan="6"><strong>MASS - WEIGHT (APPROXIMATE)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 ounce (oz)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>28 grams (gm)</strong></td>
<td colspan="2"><strong>1 gram (gm)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="3"><strong>0.036 ounce (oz)</strong></td>
</tr>
<tr class="even">
<td><strong>1 pound (lb)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>0.45 kilogram (kg)</strong></td>
<td colspan="2"><strong>1 kilogram (kg)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="3"><strong>2.2 pounds (lb)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 short ton = 2,000 pounds (lb)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>0.9 tonne (t)</strong></td>
<td colspan="2"><strong>1 tonne (t)</strong></td>
<td colspan="2"><p><strong>=</strong></p>
<p><strong>=</strong></p></td>
<td colspan="3"><p><strong>1,000 kilograms (kg)</strong></p>
<p><strong>1.1 short tons</strong></p></td>
</tr>
<tr class="even">
<td colspan="5"><strong>VOLUME (APPROXIMATE)</strong></td>
<td colspan="6"><strong>VOLUME (APPROXIMATE)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 teaspoon (tsp)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>5 milliliters (ml)</strong></td>
<td colspan="2"><strong>1 milliliter (ml)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>0.03 fluid ounce (fl oz)</strong></td>
</tr>
<tr class="even">
<td><strong>1 tablespoon (tbsp)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>15 milliliters (ml)</strong></td>
<td colspan="2"><strong>1 liter (l)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>2.1 pints (pt)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 fluid ounce (fl oz)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>30 milliliters (ml)</strong></td>
<td colspan="2"><strong>1 liter (l)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>1.06 quarts (qt)</strong></td>
</tr>
<tr class="even">
<td><strong>1 cup (c)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>0.24 liter (l)</strong></td>
<td colspan="2"><strong>1 liter (l)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>0.26 gallon (gal)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 pint (pt)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>0.47 liter (l)</strong></td>
<td colspan="2"></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="even">
<td><strong>1 quart (qt)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>0.96 liter (l)</strong></td>
<td colspan="2"></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="odd">
<td><strong>1 gallon (gal)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>3.8 liters (l)</strong></td>
<td colspan="2"></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="even">
<td><strong>1 cubic foot (cu ft, ft<sup>3</sup>)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>0.03 cubic meter (m<sup>3</sup>)</strong></td>
<td colspan="2"><strong>1 cubic meter (m<sup>3</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>36 cubic feet (cu ft, ft<sup>3</sup>)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 cubic yard (cu yd, yd<sup>3</sup>)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>0.76 cubic meter (m<sup>3</sup>)</strong></td>
<td colspan="2"><strong>1 cubic meter (m<sup>3</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>1.3 cubic yards (cu yd, yd<sup>3</sup>)</strong></td>
</tr>
<tr class="even">
<td colspan="5"><strong>TEMPERATURE (EXACT)</strong></td>
<td colspan="6"><strong>TEMPERATURE (EXACT)</strong></td>
</tr>
<tr class="odd">
<td><strong>[(x-32)(5/9)] °F</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>y °C</strong></td>
<td colspan="2"><strong>[(9/5) y + 32] °C</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>x °F</strong></td>
</tr>
</tbody>
</table>

![](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 {#preface .WW-Contents-1}

Current communication technology offers the opportunity to improve
productivity and safety in railroad operations compared to previous
technology. This report documents the design and evaluation of a digital
communication device intended to improve roadway worker safety and
productivity. The goal of the study was to understand the safety
implications of new communication devices and to identify usability
issues associated with making them effective tools for their operators.

The prototype device was designed as a handheld information appliance
with wireless access to the Internet. Roadway workers tested this data
link device prototype as part of a usability evaluation. Their comments
and the results of these tests are described in this report.

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

The authors would like to acknowledge several people who helped in the
development of this work. Nicolas Malsch and Santanu Basu, from MIT,
developed the train dispatcher simulator that was the launch pad for
this project.

John K Pollard, Mike Zuschlag, and Andrew Kendra from the Volpe National
Transportation Systems Center and Emilie Roth, from Cognitive
Engineering, provided help in their own field of expertise. David
Lecumberri from MIT, helped in the early steps of the PDA application by
envisioning feasible system architecture. Timothee Masquelier, from MIT,
reviewed the appendix drafts.

Steve Jones, from Amtrak, provided the invaluable help of arranging
visits to the Central Traffic Control Center at South Station in Boston,
Massachusetts. Brian Radovich, from Amtrak, arranged the visits to work
sites and volunteered to find test users for the experiment. All the
test users, that were willing to test the device, provided excellent
ideas to improve it and showed great enthusiasm.

The Federal Railroad Administration's Office of Research and Development
sponsored the research, as part of its activities to develop Intelligent
Railroad Systems (Federal Railroad Administration, 2002).

# Table of Contents {#table-of-contents .WW-Contents-1}

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

[EXECUTIVE SUMMARY ix](#executive-summary)

[1. Introduction 1](#introduction)

[1.1 Communications Play a Vital Role in Railroad Operations
1](#communications-play-a-vital-role-in-railroad-operations)

[1.2 Research Goals 3](#research-goals)

[2. Cognitive Task Analysis 5](#cognitive-task-analysis)

[2.1 Tasks Performed by Dispatchers and Roadway Workers
5](#tasks-performed-by-dispatchers-and-roadway-workers)

[2.1.1 Dispatcher Tasks Associated with Roadway Workers
6](#dispatcher-tasks-associated-with-roadway-workers)

[2.1.2 Roadway Worker Tasks 6](#roadway-worker-tasks)

[2.2 Information Shared between Roadway Workers and Dispatchers
7](#information-shared-between-roadway-workers-and-dispatchers)

[2.3 Proposed Information Requirements
9](#proposed-information-requirements)

[3. Prototype Design 11](#prototype-design)

[3.1 Task Requirements 11](#task-requirements)

[3.2 Human-Machine Interface Requirements
12](#human-machine-interface-requirements)

[3.3 Hardware Selection 13](#hardware-selection)

[3.4 System Architecture 13](#system-architecture)

[4. Usability Evaluation 15](#usability-evaluation)

[4.1 Overview 15](#overview)

[4.1.1 Participants 16](#participants)

[4.2 Readability and Navigation 17](#readability-and-navigation)

[4.2.1 Method 17](#method)

[4.2.2 Results and Discussion 17](#results-and-discussion)

[4.3 Comparison of PDA to Voice Radio
18](#comparison-of-pda-to-voice-radio)

[4.3.1 Method 18](#method-1)

[4.3.2 Results and Discussion 21](#results-and-discussion-1)

[4.4 Conclusions 28](#conclusions)

[4.4.1 Future Directions for Research
30](#future-directions-for-research)

[Appendix A. PDA System Architecture 31](#pda-system-architecture)

[Appendix B. Questionnaires 43](#questionnaires)

[Appendix C. Form D 55](#form-d)

[Appendix D. Palm VII Characteristics 57](#palm-vii-characteristics)

[Glossary 59](#glossary)

[References 61](#references)

# List of Figures {#list-of-figures .WW-Contents-1}

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

1\. Information Flow Using PDA [12](#__RefHeading___Toc3092040)

2\. PDA System Architecture [14](#__RefHeading___Toc3092041)

3\. Main Menu (first version) [15](#__RefHeading___Toc3092042)

4\. Main Menu (second version) [16](#__RefHeading___Toc3092043)

5\. Timeline for Work Request Procedure [20](#__RefHeading___Toc3092044)

6\. Average Task Completion Times [22](#__RefHeading___Toc3092045)

7\. Errors Associated with Communications, Safety, and Work Requests
[23](#__RefHeading___Toc3092046)

8\. Information Retrieved [24](#__RefHeading___Toc3092047)

A‑1. PDA Screen Shots (1) [32](#__RefHeading___Toc3092048)

A‑2. PDA Screen Shots (2) [33](#__RefHeading___Toc3092049)

A‑3. PDA Screen Shots (3) [34](#__RefHeading___Toc3092050)

A‑4. PDA Screen Shots (4) [35](#__RefHeading___Toc3092051)

A‑5. Dispatcher Interface [40](#__RefHeading___Toc3092052)

A‑6. Database Manager Interface [41](#__RefHeading___Toc3092053)

# List of Tables {#list-of-tables .WW-Contents-1}

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

1\. Roadway Workers Who Interact with Dispatchers
[5](#__RefHeading___Toc527520622)

2\. Other Workers Who Interact with Dispatchers
[6](#__RefHeading___Toc527520623)

3\. Tasks Performed Using the PDA [11](#__RefHeading___Toc527520624)

4\. Situation Awareness Categories [25](#__RefHeading___Toc527520625)

# EXECUTIVE SUMMARY {#executive-summary .Executive-Summary}

## Communications between Roadway Workers and Dispatchers {#communications-between-roadway-workers-and-dispatchers .Appendix-2}

The present study examined the use of data link (digital communications)
from the roadway worker perspective. What communication problems does
the roadway worker encounter? Does data link offer a solution to these
communication problems? What are the requirements that must be addressed
so that roadway workers can effectively use data link?

The use of current communication technologies to meet roadway worker
information requirements was examined. An application was developed for
use on a handheld computer with wireless communication capabilities that
enabled the roadway worker to obtain information from the dispatcher
only previously available by telephone or voice radio. This
communication device was intended to supplement the use of voice radio
and telephone.

The first goal of this study was to understand the communication link
between roadway workers and train dispatchers. Communications between
the two groups were observed at a Traffic Control Center as well as in
the field. Dispatchers were interviewed regarding their conversations
with roadway workers, and roadway workers were interviewed regarding
their interactions with dispatchers.

Two types of messages between dispatchers and roadway workers were
identified. The first type included those messages that followed a
protocol governed by operating rules that everybody must follow.
Examples of these messages were movement permits, authorization to foul
the track, authority to pass a stop signal, and submission of speed
restrictions. The second type included messages that did not follow a
structured pattern. Examples of these unstructured messages were verbal
permission for signal maintenance, detailed description of job being
performed on the track, and updates about expected time to complete a
given job.

Dispatchers and roadway workers were also questioned about potential
tools aimed at improving their communication system. While dispatchers
found benefits in shifting the structured messages to computer-based
media, roadway workers did not see a significant benefit. In a previous
study examining the use of data link (Malsch, Sheridan, and Multer,
2004), dispatchers preferred the idea of receiving work requests
directly on their computer monitors rather than over the radio. They
could see the queue of incoming messages and answer them according to
their priorities, rather than on a first come first served basis.
Dispatchers also saw potential in additional decision aids that could be
implemented once the work requests had been electronically received,
such as highlighting on their screens the section of track being
requested.

While roadway workers saw benefits for the dispatchers, they also
believed that sending just a few daily work requests electronically
would be a burden and not an advantage. They were concerned about the
ease with which they could send these work requests using a handheld
computer. They were particularly worried about whether they would
receive adequate training. Nevertheless, they saw benefits in using data
link technology to obtain information about railroad operations that
they normally would receive by voice radio from the dispatcher. The
roadway workers saw great potential in retrieving important information
in real time such as train location, or special rules that apply to
specific sections of track.

## Design and Evaluation of a Data Link Prototype {#design-and-evaluation-of-a-data-link-prototype .Appendix-2}

Based upon observations and interviews with dispatchers and roadway
workers, a prototype communication application was developed to perform
two types of tasks: request information related to operation conditions
and request work authorizations. Despite the roadway workers' concerns
for usability and training with respect to sending work requests by data
link, this function was included because of its potential to assist
dispatchers in reducing workload. The complexity of the application was
reduced to improve roadway worker acceptance of the device.

The prototype device operated on a personal digital assistant (PDA) with
wireless access to the Internet. Roadway workers volunteered to test the
prototype in a series of laboratory experiments to evaluate its
usability and to compare it with the voice radio environment.

In terms of usability, the participants indicated that all the features
included in the prototype were easy or very easy to use. At the same
time, they agreed that if they had the opportunity to use such an
information device in real railroad operations, they would use it to
submit work requests and to retrieve information related to operating
conditions such as updated schedule of trains.

In comparison to the voice radio environment, the data link device
resulted in safer operations, improved knowledge of potential risks, and
communications that were more accurate. At the same time, it resulted in
a reduced number of work requests submitted to the dispatcher and slower
communications.

# Introduction

## Communications Play a Vital Role in Railroad Operations

Of the many employees working in railroad operations, three groups play
a key role: railroad dispatchers, train crews, and roadway workers.
Railroad dispatchers ensure the safe movement of trains, equipment, and
personnel on the track. Each dispatcher manages a portion of the track
network. Locomotive engineers and conductors operate and manage the
train. They follow the instructions given by dispatchers through
movement authorities and the signal system (wayside or in-cab). Roadway
workers maintain and occasionally construct the railroad infrastructure,
which includes: track, signals, switches, station platforms,
electrification, bridges, tunnels, embankments, and culverts.

Communications are vital in making railroad operations safe and
efficient. All three groups of railroad employees engage in a continuous
exchange of information. Voice radio currently serves as the primary
medium for sharing information. In addition to communications between
operating staff, two-way communications also take place between
operators and equipment along the right-of-way as well as at the
dispatch center. In centralized traffic control territory, switches and
signals receive commands from the dispatcher's computer. These commands
determine the track over which the train will travel as well as any
speed restrictions. Wayside signals communicate information about
movement authorities to the train crews. Except in automatic block
signal (ABS) territory and dark territory, remotely located equipment
provides feedback to the dispatchers about the actual state of the
switches and signals, as well as information about train location. In
ABS and dark territory, voice radio serves as the only medium for
communication among dispatchers, train crews, and roadway workers.

Voice radio communications are vital to the safe and efficient operation
of the railroads. Voice radio supports two types of communication tasks.
The first type includes safety-critical communications related to train
movements and allocation of track between roadway workers and trains.
The second type includes tasks that are important to the efficient
operation of the railroad. For example, the dispatcher may forward
information about train movements (i.e., current train delays) to
roadway workers or train crews.

The characteristics of voice radio and the way railroad operations are
conducted have contributed to several problems. First, the available
voice radio bandwidth is inadequate to support current communication
needs (Federal Railroad Administration, 1994; Roth and Malsch, 1999).
The Federal Communications Commission has allocated 208 channels (182 in
the VHF band and 26 in the UHF band) for railroad operations (Code of
Federal Regulations, 2000). However, within a geographic region a much
smaller number of channels are available (e.g., 3 or 4). Voice
communications for main line operations are typically restricted to a
single channel. In addition, only one person can communicate on a
channel at a time. Other workers who want to use the same channel must
wait until the channel is clear. As a result, voice radio channels are
congested.

The inadequate communication bandwidth is also partly due to the
changing nature of how dispatchers and roadway workers perform their
jobs. As new technology in the form of voice radio and train control
systems have been implemented, block operator positions have been
gradually eliminated. Block operators performed a job similar to that of
dispatchers, but over a smaller geographic territory. They communicated
with dispatchers over wire line telephones and with train crews using a
hoop with a string. As block operator positions were eliminated, the
dispatcher became responsible for managing a larger territory with a
concomitant increase in communication workload. By contrast, the roadway
worker has not experienced the same increase in communication workload.

Second, the temporal nature of auditory information imposes a
significant burden on railroad employee's memory. Railroad workers
adapted by recording important information on paper. However, the time
it takes to record this information places a burden on the dispatcher's
memory and increases workload.

Advances in communication technology have the potential to improve
railroad safety and productivity. The use of data link (defined as
discretely addressed digital telecommunications) has been proposed as a
communication medium to supplement voice radio. Data link uses the
communication bandwidth more efficiently than voice radio. Information
transmitted digitally can be presented aurally or visually. These
characteristics offer opportunities to address the limitations posed by
voice radio. However, if the needs and limitations of operators are
clearly understood, designers are more likely to use new technology in
ways that positively impact safety and productivity. As mentioned
earlier, new train control technology has increased the communication
load for the dispatcher. Simply increasing bandwidth by adding channels
could adversely impact the dispatcher's performance if the design of the
system does not consider the communication load that the dispatcher can
handle safely. For example, if data link technology enables many people
to simultaneously send the dispatcher messages, the dispatcher may still
be only able to attend to one message at a time. To avoid communication
overload, the dispatcher will need a way to filter and organize the
incoming messages. Similarly, roadway workers may be frustrated by a
lack of response when their requests for information or work
authorization go unanswered longer than they expect.

The current study was part of a research program to measure how the data
link user interface impacts human performance in railroad operations. A
goal of this study was to understand the safety implications and
usability requirements for roadway workers to take advantage of data
link technology.

The first study in the program examined the use of data link by the
dispatcher (Malsch, 1999 and Basu, 1999; Malsch, Sheridan, and Multer,
2004). This research compared dispatcher performance in the current
voice radio environment to a data link environment, using a train
dispatcher simulator with data link capabilities. In this system, a
computer-simulated train operates while the experimenter simulates all
other railroad agents, including roadway workers. When data link
capabilities were enabled, dispatchers received information from all the
trains in their territory, as well as from roadway worker crews in
visual form using an e-mail-like application. When data link
capabilities were unavailable, dispatchers communicated with trains and
roadway worker crews by voice radio.

The results indicate that data link was an efficient tool for
communicating complex messages, particularly where acknowledgement of
messages was required. Data link improved train and roadway worker
safety, and situation awareness while lowering the dispatcher\'s
perceived workload compared to voice radio. Data link was less efficient
for communicating simple or urgent messages.

During the first study, dispatchers made several comments that addressed
the use of data link in the field as well as in the traffic management
center. In particular, they made several comments relevant to the use of
data link by roadway workers.

These comments are listed below:

-   Since, roadway workers currently lack data link communication tools,
    they wondered how the work crews in the field would send and receive
    digital messages. They also raised concerns that some roadway
    workers might be unfamiliar with computers.

-   Dispatchers liked the idea of data link. Data link enabled
    dispatchers to control the order in which messages were responded
    to. When using voice radio, dispatchers are more likely to answer
    messages on a first-come first-served basis because they often don't
    know the reason for the call. With data link, they could assign
    priorities to incoming messages and deal first with the most
    important ones. This finding was also supported by
    Vanderhorst's (1990) research comparing data link to voice radio.

-   The dispatchers appreciated not having to repeat a message many
    times due to low quality voice radio transmissions. Eliminating the
    repetition of messages decreased workload and left more time for
    other activities.

## Research Goals

The present study examined one form of data link from the perspective of
the roadway worker.

-   What communication problems does the roadway worker encounter?

-   Does data link offer a solution to these communication problems?

-   What are the requirements that must be addressed so that roadway
    workers can effectively use data link?

The use of current communication technologies was examined to meet
roadway worker information requirements. An application was developed
for use on a personal digital assistant (PDA) with wireless
communication capabilities that enabled the roadway worker to obtain
information without requiring assistance from the dispatcher. The
information was previously available only from the dispatcher by
telephone or voice radio.

The project was divided in three main parts:

-   Cognitive Task Analysis

-   Prototype Design

-   Usability Testing

The cognitive task analysis (CTA) describes the process by which the
information requirements of roadway workers were established for the
development of the roadway worker communication tool. The prototype
design section describes the development of the hardware and software to
meet the roadway workers information requirements. The usability tests
describe several methods and results of two types of tests to evaluate
and improve the effectiveness of the communication device developed.

# Cognitive Task Analysis

In previous work, a CTA (Roth Malsch and Multer, 2001) was conducted to
learn how train dispatchers manage and control trains. This report was
helpful during the development of the present project but did not
specifically address the roadway worker's perspective.

A focused CTA was conducted to understand the requirements of a digital
communication device that would facilitate roadway worker's
communications with the dispatcher. The CTA consisted of observing
communications between roadway workers and dispatchers and interviewing
both groups. Communications between the groups were observed at a
traffic management center as well as in the field. Dispatchers were
questioned about their conversations with roadway workers, and roadway
workers were interviewed regarding their conversations with dispatchers.
Dispatchers and roadway workers were questioned about potential tools
aimed at improving their communications.

## Tasks Performed by Dispatchers and Roadway Workers

This section describes the interactions between roadway workers and
dispatchers, and the tasks each group performs. Table 1 shows the
variety of roadway workers and the types of transactions that take place
between the roadway worker and the dispatcher.

  -------------------------------------------------------------------------------------
  []{#__RefHeading___Toc527520622   
  .anchor}Table 1. Roadway Workers  
  Who Interact with Dispatchers     
  --------------------------------- ---------------------------------------------------
  **Operator**                      Type of Communication

  Point conductor                   Serves as a focal point for communications between
                                    several roadway workers and the dispatcher.
                                    Transactions typically concern track authorities
                                    (i.e., Form D and Foul Time). The presence of the
                                    point conductor simplifies the work of the
                                    dispatcher by reducing the number of people with
                                    whom the dispatcher must communicate.

  Flagman/Conductor                 Requests track authority to protect railroad
                                    roadway workers or contractors.

  Electrification worker            Conversations between electrification workers and
                                    dispatchers are rare due to the presence of the
                                    point conductor. However, when they do interact,
                                    the issues are similar to those for the point
                                    conductor.

  Signal maintainer                 Requests permission to shut down signals or to put
                                    them in local mode.

  Track car foreman                 As the operator in charge of a track car, the track
                                    car foreman asks permission to operate a track car
                                    and to pass stop signals.

  Work extra train crew             Operate trains and track equipment to bring
                                    materials into the work area. Their communication
                                    with the dispatcher addresses the following
                                    information: equipment left on the track, new speed
                                    restrictions, and directions for routing the train,
                                    and requests for switch changes.

  The operator labels represent     
  terminology used by Amtrak along  
  the Northeast Corridor.           
  -------------------------------------------------------------------------------------

### Dispatcher Tasks Associated with Roadway Workers

When a dispatcher receives a request for roadway worker protection, the
dispatcher decides whether to grant, modify, or deny the request. If the
dispatcher grants permission to work, (under Foul Time, Form D, or
verbal permission) the track is placed off-limits (blocked) for other
uses. In Central Traffic Control (CTC) territory, blocking a track
protects the roadway worker since it prevents the dispatcher from
routing trains on that track. Switch operation is restricted, and the
signals (wayside and in-cab) for the blocked track will display a stop
signal at both ends to prevent movement by unauthorized track vehicles.
In ABS and dark (unsignalized) territory, the roadway workers must block
the switches manually.

Once authorization for track use is granted to a roadway crew and the
track is blocked, the dispatcher has delegated authority over that track
to the roadway crew. Roadway workers can change the state of a switch by
manually using the local switch, or they may ask the dispatcher to make
the change remotely.

While roadway workers perform their tasks, they continue to interact
with the dispatcher. These interactions include making additional work
authorizations, adding and removing speed restrictions, and fulfilling
requests for updates on train location. When the job is completed, the
responsible crew foreman releases the track back to the dispatcher. In
CTC territory, the dispatcher unblocks the track making it available for
other uses.

The dispatcher also communicates with other railroad employees in the
field. Table 2 describes the communications associated with people other
than roadway workers.

  --------------------------------- ---------------------------------------------------
  []{#__RefHeading___Toc527520623   
  .anchor}Table 2. Other Workers    
  Who Interact with Dispatchers     

  **Operator**                      **Types of Communication**

  Bridge operator                   The bridge operator calls the dispatcher when there
                                    are ships that require the bridge to be opened. The
                                    dispatcher unlocks the bridge (the display terminal
                                    displays the track section as occupied) and control
                                    is given to the bridge operator. After the bridge
                                    operator returns control of the track to the
                                    dispatcher, the bridge is locked and the track is
                                    available for routing and maintenance operations.

  Train crew (freight conductor &   Reports tons carried, number of cars
  locomotive engineer)              (loaded/empty), and engine number.
  --------------------------------- ---------------------------------------------------

### Roadway Worker Tasks 

Roadway workers' tasks include inspection, construction, maintenance,
and repair of the track infrastructure (i.e., track, bridges, signal,
and communication systems, and electric traction systems) on or near the
track.

When a roadway worker wants to perform a job on the track, several steps
are followed, as shown below:

1.  Collect information.

> Examples of information needed by roadway workers include:

-   Milepost number

-   Track numbers

-   Territory characteristics (i.e., rules that apply on each track,
    maximum train speed, signal system or dark territory)

-   Name of dispatcher who controls the territory

-   Train timetable schedule around working site

2.  Request work authorization from the dispatcher (i.e., Foul Time or
    Form D) when necessary.

3.  Conduct a job briefing with the crew.

4.  Give control of the track back to the dispatcher.

5.  Make sure work area is safe and secure.

The roadway worker obtains timetable schedule and territory information
from the operating rulebook. For the roadway workers interviewed in this
study, this rulebook contained only scheduled passenger train
information. Unscheduled trains (i.e., freight, work extras), and
commuter trains with higher frequency were not shown. The roadway worker
requires updated information regarding the location of all the trains
that could interfere with the job. The roadway worker calls the
dispatcher for schedule updates and for unscheduled train information.

The crew foreman is responsible for the protection of other crewmembers
and conducts the job briefing. The job briefing covers those activities
each member will perform as well as safety issues. A major
responsibility of the foreman includes obtaining work permission from
the dispatcher.

Track inspection is another frequently performed activity that has a
different set of communication requirements from those associated with
tasks performed by maintenance of way crews. Track inspectors operate
track cars through a territory examining the track for defects. Track
cars pose a special challenge for the dispatcher. A track car is a piece
of equipment other than a train, used for inspection or maintenance. In
signalized territory, track cars do not usually shunt track circuits so
the dispatcher cannot determine even their approximate location, as they
can with trains. For this reason, track cars need movement authority
(Form D, Lines 2 and 3) and authority to pass stop signals (Rule 241).

Other general-purpose trains, called work-extra trains carry equipment
and work crews to job sites. These unscheduled trains shunt track
circuits, but may remain on the track for a specified interval.
Work-extra trains also need movement authority from the dispatcher
(i.e., Form D, Line 4).

## Information Shared between Roadway Workers and Dispatchers

Messages exchanged between dispatchers and roadway workers were divided
into two types: structured and unstructured. Structured messages follow
a protocol governed by operating rules that everybody must follow.
Unstructured messages included all other messages. Examples of each
message type are as follows:

#### **Structured Messages** {#structured-messages .unnumbered}

1.  Movement Permit Form D

According to the Amtrak operating rules (NORAC, 1999), the dispatcher
issues Form Ds to restrict or authorize train movements. Form Ds are
also issued to convey instructions not covered in the operating rules.
Although Form Ds are intended primarily for trains, one interviewed
dispatcher indicated they grant 90 percent of Form Ds to work crews and
only 10 percent to trains. A roadway worker may receive a Form D, Line 4
"if the work involves on-track equipment or will disturb the track or
catenary structure."[^1]

Once a dispatcher grants a Form D and puts it into effect, very limited
changes may be made to the authorization. Changes include: cancellation,
permission to continue to operate a track car in a given direction under
new limits (Line 2), and "track is clear" information (Line 13) or train
or track car ahead has cleared the limits of the following track car's
(Line 2) authority. A more detailed description of a Form D is given in
Appendix C.

2.  Foul Time (track and time).

A qualified roadway worker or contractor whose activities will
[not]{.underline} disturb the track or catenary may receive
authorization from the dispatcher to foul the track. For example, a
roadway worker under Foul Time protection may operate a crane over the
track. Activities like replacing ties or leaving heavy equipment on the
track require Form D authorization. Issuing Foul Time (also called
*track and time* by some railroads) to roadway workers has become a time
consuming part of a dispatcher's job. A dispatcher may easily have three
to seven active authorities involving Foul Times within their territory.

3.  Authority to Pass a Stop Signal (Rule 241).

Normally, trains and track cars are prohibited from passing a stop
signal. Rule 241 authorizes trains or track cars to pass a stop signal.
Dispatchers grant this authority so track cars can enter an interlocking
where inspection or maintenance work will take place. Normally,
dispatchers grant permission to operate a track car (Form D, Line 2),
accompanied by permission to proceed past a stop signal (rule 241 or
Form D, Line 3). The choice of authority (Rule 241 or Form D, Line 3)
depends on the dispatcher's preferences.

4.  Speed Restrictions.

Repair crews communicate new speed restrictions to dispatchers. These
speed restrictions are sent daily to trains and dispatchers and may be
included in a Form D.

#### **Unstructured Messages** {#unstructured-messages .unnumbered}

In railroad operations, different situations arise when a dispatcher
must issue verbal permission to a roadway worker. For example, a signal
worker needs verbal permission to put an interlocking in local mode or
to temporally shut it down.

Another type of interaction between dispatchers and roadway workers
occurs when the roadway workers are already working under protection.
Dispatchers usually ask work crews for details on time restrictions. For
example, a dispatcher may ask, "How long will it take to remove
equipment from the track?" Dispatchers also ask for details about the
job being performed. This information enables the dispatcher to better
manage unanticipated events.

A roadway worker who has trouble communicating with another railroad
employee may call the dispatcher to request that the message be relayed,
or they may ask the dispatcher to make the telephone call.

## Proposed Information Requirements

A goal of the interviews with both dispatchers and roadway workers was
to elicit information requirements associated with their communications
tasks. Their comments are summarized below.

1.  Data link-based exchange of work authorization.

Dispatchers liked the idea of receiving and granting data link
transmitted work requests. They envisioned a visual interface with which
they could browse through a list of work requests and answer each
request in the order they considered appropriate. Other anticipated
benefits were: saving time, improved legibility of Form Ds, and a
verification system that prevented or minimized common human error such
as blocking a track that does not match the one given in the work
permission.

For such a tool to be perceived as beneficial, it would need to minimize
typing requirements. If much typing was necessary, little difference was
perceived between written and electronic work authorizations.
Confirmation that the message was received was also important to
dispatchers. The dispatchers expressed concern about whether the
currently well-established procedure of acknowledgments could be
replicated electronically.

Roadway workers saw little need for computer-generated issuance of work
requests because they made few requests per day. If they did not use a
handheld computer to send work requests, they would not use it to
receive work authorizations.

Roadway workers also expressed concerns about training and security
related to issuing work requests. Some roadway workers were unfamiliar
with computer devices so the question of training was raised. What kind
of training would be needed to learn how to operate the device? The
roadway workers also worried about unauthorized people using the device
to make work requests. They did not understand how the system could tell
if the worker sending the request was an authorized user.

2.  Real time or near real time train location information.

The roadway workers expressed interest in receiving train location
information comparable to the information dispatchers currently receive.
One instructor said, "Information about train location is already at the
Traffic Control Center. Why don't we share it with the ones that will
make good use of it?" Access to near real time or real time train
locations would help them because they wanted more accurate information
about train location than found in paper versions of the timetable
schedules. It would help them plan their activities and when to request
work authorization from the dispatcher. The information would be even
more valuable if it included all trains on the track, not just the
scheduled ones.

The roadway workers who were interviewed made several suggestions for
features that embody the use of computer-based exchange of work
authorizations and access to more timely information about train
location. Some proposed features of this handheld device were:

-   Show automatically generated schedule, including delays of the
    trains that are supposed to arrive at the roadway worker's location.

-   Request information such as: where is a particular train or what is
    the next train at this interlocking?

-   Warn of nearby trains. Whenever a train enters the same block as the
    roadway workers or an adjacent block, this device could send them a
    warning.

-   Knowledge about the time they can ask for Foul Time or the time they
    have to wait before asking for Foul Time.

# Prototype Design

## Task Requirements

Based upon the CTA, a software application was developed for use on a
PDA with wireless communication capabilities. The application addressed
the user requirements discussed in Section 2.3 and enabled the operator
to perform two tasks: request information related to operating
conditions, and request work authorization. The application was
specifically designed for use on the railroad, and was intended to
facilitate communication between roadway workers and dispatchers. Table
3 shows the type of information that may be requested, and the work
authorizations allowed. Figure 1 shows the information flow using the
PDA.

  ------------------------------------- ---------------------------------
  []{#__RefHeading___Toc527520624       
  .anchor}Table 3. Tasks Performed      
  Using the PDA                         

  **Information Requests**              **Work Authorizations**

  Train Status                          Form D

  Train Schedule                        Foul Time

  Territory Information                 Cancel Work Authorization

  Track Out of Service Report           

  Form D/Foul Time Under User Authority 

  Other                                 
  ------------------------------------- ---------------------------------

This prototype was designed to enable the roadway worker to request
information or work authorization with minimal data entry. The ability
to send work requests was included because it could potentially reduce
dispatcher workload. It also had the potential to reduce communication
errors between roadway workers and dispatchers.

Database requests were answered by a computer containing the train
timetable schedule. The dispatcher handled requests for work
authorities.

![](media/image6.wmf)

[]{#__RefHeading___Toc3092040 .anchor}Figure 1. Information Flow Using
PDA

## Human-Machine Interface Requirements

The next step in the development of the prototype was to develop the
user interface that roadway workers would use to communicate with
dispatchers. Roadway Worker Protection (RWP) class instructors were
interviewed to develop a set of conceptual specifications of a wireless
handheld computer that could be used by roadway workers.

The instructors suggested the device should be smaller than a laptop
computer and simpler to use. Roadway workers did not like the idea of
carrying a laptop computer. They described a portable device like a
pager, PDA, or mobile phone that could give updated train location
information. The instructors also expressed concern about training
issues. In particular, they were concerned about the fact that some
roadway workers were not familiar with computers or security and
authentication.

## Hardware Selection

A device was selected that had wireless access to the Internet, and
could be used anywhere along the track. A web site was used as the
network interface for the prototype. The application also required a
simple user interface to enable the roadway worker to operate the system
with minimal training.

The following devices were considered:

-   Laptop computer with wireless modem

-   Pager

-   Cellular phone

-   Handheld computer with wireless modem

Although a laptop offered considerable flexibility in terms of available
features, this option was rejected because it was too big to carry.
Interacting with the device by using a keyboard was also considered
unacceptable by the user population.

A pager or a cellular phone was considered because both had wireless
coverage along the track and roadway workers were familiar with them.
Although a pager or a cellular phone could receive information, at the
time that the selection was made, data entry was difficult, limited, and
the visual display was considered too small to display enough
information.

The fourth option considered was a handheld computer referred to as a
personal digital assistant or PDA. These devices are typically used as
organizers for managing e-mail, as well as for storing contact and
calendar-related information. They have visual displays larger than a
cell phone, but are smaller than a laptop computer. The PDA can also be
programmed to perform a variety of tasks, and it offers a range of
options for manipulating information. The most common mode of
interaction involves using a pointing device or stylus. Just prior to
the beginning of this study in June 1999, versions became available with
wireless modem technology and Internet access.

For the first prototype, a Palm VII Personal Digital Assistant was
selected. It had built-in wireless Internet access, a simple user
interface, was small, and had good technical support for developers.

## System Architecture

Figure 2 shows the system architecture. Like a mobile phone, the PDA
communicated with a base station that consisted of an antenna and a
server. The antenna received the wireless message from the PDA. The
message was sent to the server connected to the antenna and the server
redirected the message to the appropriate destination via the Internet.
Through this transaction, the PDA sent and received information to a web
server. A number of servers look for requests sent by the PDA, the
dispatchers, or a database manager. These servers represent the core of
the system as they redirect the request to the appropriate recipient. A
work authorization was sent to the dispatcher while an information
request was answered by the system without interrupting the dispatcher
by querying the database.

Dispatchers interacted with the system via web pages. Through this
interface, they were able to receive work requests from roadway workers
and send work authorities.

The database contained train timetable schedule, current delays,
schedule of trains not part of the timetable schedule, track out of
service under Form D or Foul Time, and territory information (maximum
speed, dispatcher in charge, rules that apply). In the PDA prototype
developed for this project, the database was modified manually by a
database manager using another interface of simple web pages. For a more
detailed description of the system architecture, see Appendix A.

![](media/image7.wmf)

[]{#__RefHeading___Toc3092041 .anchor}Figure 2. PDA System Architecture

# Usability Evaluation

## Overview

The goal of the usability evaluation was to identify human factors
issues that must be addressed for the device to be successfully
implemented in the railroad environment. It was important to gauge user
acceptance, and to identify human factors design issues that need to be
considered as this device evolves toward a more mature design.

The design evolved through an iterative process in which user
requirements were turned into an initial prototype and modified based on
user feedback. The first round of usability testing focused on the
information content that the tool should display, and tasks the user
would perform. The same roadway workers were used (primarily
conductor-flagmen), who made suggestions about the device during the
CTA. When the first version of the PDA was completed, feedback was
solicited from instructors of a Railroad Worker Safety class.

In the first prototype, train location and territory information was
included and Form D requests were limited. It also included the ability
to request Foul Time and submit speed restrictions. The main menu is
shown in Figure 3.

![](media/image8.png){width="1.6666666666666667in"
height="1.6666666666666667in"}

[]{#__RefHeading___Toc3092042 .anchor}Figure 3. Main Menu (first
version)

Useful comments were received concerning features that were missing from
the first version of the prototype that would be helpful in revenue
service. After carefully considering the comments and suggestions of the
users, the following modifications were made:

-   The *Next Train* (next train at a given interlocking[^2]) option was
    removed since it was redundant of *Train Schedule at Working Site*
    (train schedule at a given portion of track during a given time
    period).

-   A *Train Status* option (general information about a train: last
    interlocking, next interlocking, direction of travel and delays) was
    added.

-   To simplify the user interaction and to better reflect actual
    railroad operations, modifications were made to the procedure for
    requesting a Form D and two options were added. The first option
    enabled the worker to identify current track out of service and the
    second option facilitated the cancellation or fulfillment of a Form
    D.

-   The Foul Time request was revised so that it was similar to
    requesting a Form D.

-   After discussions with the user population, speed restriction
    requests were removed. This feature was removed to simplify the
    interface as the roadway workers who were interviewed indicated that
    they requested speed restrictions less often than requesting track
    use authorizations like Foul Time and Form Ds.

After revising the initial prototype, the main menu looked like the
display shown in Figure 4.

![](media/image9.png){width="1.6666666666666667in"
height="1.6666666666666667in"}

[]{#__RefHeading___Toc3092043 .anchor}Figure 4. Main Menu (second
version)

The revised prototype was shown to a train operations manager of an
intercity passenger railroad. The manager commented that this tool could
be useful to other railroad operating staff. This tool would enable the
manager to monitor the state of the railroad network outside of the
office environment where these information displays are traditionally
located.

Following the preliminary informal tests, more formal usability tests
were conducted in a laboratory environment. Two series of laboratory
tests were performed. One test addressed readability and navigation. The
second test compared the usability of the new device to communication by
voice radio.

The readability and navigation test was performed first, after which the
prototype was revised. Next, performance with the handheld PDA was
compared to performance using the voice radio.

### Participants

Nine conductor-flagmen employed by an intercity passenger railroad
participated. Three conductor-flagmen participated in the readability
and navigation test, while six others participated in the comparison
with voice radio. Out of the nine participants, one was female and eight
were male. The participants ranged in experience from 1 to 37 years,
with an average railroad work experience of 16 years. Each participant
received compensation equivalent to a full day of labor.

All participants were familiar with radios, PCs, pagers, cellular
phones, the Internet, and e-mail. All participants except one were
unfamiliar with handheld devices such as the one used in the study.

## Readability and Navigation

### Method

Three conductor-flagmen participated in the usability test. A thinking
aloud protocol was used in which participants spoke aloud as they
performed a variety of tasks. If the participant did not speak during
the execution of a task, the experimenter prompted the participant with
a series of questions.

[Materials]{.underline}

A digital tape recorder was used to record the participants' comments
during each task. The PDA was used to record the actions of the
participant while using the device. A personal computer with a Pentium
III processor was used to present the tasks to the participant. Paper
worksheets were used to write down comments and answers to the tasks.

[Procedure]{.underline}

Users were trained for 30 minutes on the use of the PDA, and then the
steps to complete each task were explained. Participants interacted with
a simulated train schedule modeled after an actual schedule with which
they were familiar. The database included scheduled intercity passenger
trains, commuter trains, and unscheduled trains. The user was given a
list of tasks to complete. These tasks required the user to request
information or obtain work authorization for a section of track using
the PDA. While sitting in front of a personal computer, the participant
received one task at a time and wrote the answer to each task in the
worksheets. The participant used the PDA to execute each task while
\"thinking aloud.\" The experimenter did not answer questions unless the
user was stuck and unable to continue. The experimenter asked the user
questions, especially when the user was not saying anything. The
experimenter asked usability questions about requesting information and
work authorizations.

At the beginning of the test, demographic information was collected.
This demographic information included years of experience and background
knowledge of data link devices. At the end of the test, questions were
asked about how the application could be improved, task realism, and how
the information was presented to the user (i.e., font style, size,
navigation procedures). It took approximately 3 hours to complete all
the tasks and the questionnaires.

[Observations and Measurements]{.underline}

From the recorded comments, difficulties with the user interface and
errors made while using the device (i.e., selection of wrong menu) were
identified.

From the questionnaires, subjective measures were collected regarding
the usability of the device, as well as comments about improvements and
potential changes in the way the work requests were handled.

From the log files, the number of times each feature was used was
measured, as well as errors made, recovery from errors, and the task
completion time.

### Results and Discussion

From the readability and navigation test, several changes were
identified to improve the user interface. The most important change was
to the last steps of the Foul Time request, which was previously
confusing for the participants. Roadway workers had to acknowledge Foul
Time received from dispatchers. The process was designed so the incoming
acknowledge request displayed the message "Foul Time not effective,"
which led some participants to think that the Foul Time had not been
accepted by the dispatcher. The header message "Foul Time not effective"
was replaced by header "Please confirm Foul Time."

In addition, the process of acknowledging Foul Time required selecting
the desired action ("accept" or "do not accept") and then tapping a
"send response" button. These requirements were simplified by using two
buttons labeled "accept" and "do not accept," which automatically
executed the intended operation without any further user action.
Finally, the layout of the Foul Time message was modified to fit on one
screen to eliminate the need for a vertical scroll bar. The same
modifications were applied to the Form D request to maintain
consistency.

Other changes included the following:

-   Use of the a.m./p.m. time format.

-   Reword menu titles and commands to be consistent with railroad
    operations vocabulary.

-   Provide a link to the main menu from all submenus that previously
    lacked this capability.

-   Add information sent with the train status report to include engine
    number and numbers of cars in the train consist.

It was also discovered that although the font size and the overall
device size could be larger, the information was presented in a readable
and organized way. The font used was Palm TD 9 (the default font for
plain text in the Palm VII). The menu structure was rated as easy to
navigate, however, the vertical scroll bar posed usability problems
because it was only six pixels wide which made it hard to tap the
correct location. This problem was solved by letting the participants
use the built in scroll button. The screens used to generate and send
requests were considered complete, easy to understand, and realistically
reflected railroad operations needs. Response time was slow when sending
and receiving information in the form of information requests or
requesting work authorizations. Users did not get immediate response to
their requests. This speed was limited by the slow transmission speed of
current wireless data communications (7200 baud).

## Comparison of PDA to Voice Radio

### Method

[Purpose]{.underline}

The purpose was to evaluate how the PDA affected roadway worker
performance compared to the two-way radio. It was also important to
identify usability issues that a handheld wireless communications device
would need to address before roadway workers could use it as part of
their job. The goal of this study was to identify the impact of the
current user interface on task performance and user acceptance.

[Participants]{.underline}

Six conductor-flagmen participated in this evaluation.

[Materials]{.underline}

The materials used in the evaluation consisted of one Palm VII PDA and
two VHF radios (Motorola-MT1000). The participant used one radio and the
experimenter used the other. The participant was also given a book of
operating rules, two trains schedules (one for inter-city trains and one
for local commuter rail trains) for the territory on which the
participant would be responsible for, as well as a worksheet to write
down information.

[Procedures]{.underline}

After welcoming the participant, the experimenter solicited demographic
information. Each participant received 70 minutes of training on the
features of the device, followed by practice on their own until he or
she was comfortable with its operation.

Participants carried out a series of tasks with the Palm VII and the
radio, which required knowledge of train timetable schedules. The train
timetable schedule was modeled after a schedule with which the
participants were familiar. The timetable included scheduled intercity
passenger and commuter trains as well as unscheduled trains. After
completing one set of tasks with the Palm VII, they carried out another
set of tasks with the radio. The participant completed one task before
beginning a new one. Each task was independent of the others, however,
some tasks were designed so they could not be accomplished (because of
train schedule conflict for example). In that situation, the user was
instructed to report the problem to the experimenter. During each group
of tasks, the experimenter paused the test several times to measure
situation awareness. The participant completed a set of questions as
shown in Appendix B, concerning events that recently occurred.

At the end of the evaluation, the participant answered questions about
PDA usability, ways to improve the PDA, comfort level, task realism,
workload, and implementation issues. The questions are listed in
Appendix B. It took approximately 2½ hours to complete the tasks and the
questionnaires.

[Observations and Measurements]{.underline}

All tasks were presented to the participant on a computer monitor. The
participants' use of the Palm VII was recorded and stored in a computer
file. In the voice radio condition, all of the conversations were
recorded on audiotape.

Time spent gathering information was measured as well as requesting and
canceling work authorizations. Several kinds of errors were measured.
These errors included work requests that should have been sent but were
not, work requests that should not have been sent, communication errors,
and safety errors.

From the questionnaires, situation awareness was measured in terms of
the trains noticed by the roadway worker as potential hazards, as well
as characteristics of the territory (i.e., maximum train speed).
Subjective measures were collected relating to user acceptance and
changes in workload, suggestions for PDA improvement, safety concerns,
and other potential uses of the PDA.

To evaluate the overall efficiency of the application, several measures
were taken. The specific measures that were taken are as follows:

**[Time measures]{.underline}**

-   [Task completion time:]{.underline} included the time to complete a
    single task.

-   [Time to complete a work request or a work
    cancellation:]{.underline} included the time from the initiation of
    the request until it was completed and acknowledged. In the voice
    radio condition, these times were obtained from the tape recordings.
    When computing these times using the PDA, an estimate was made.
    Measuring the actual time when the roadway worker started to fill
    the request or when the answer arrived at the PDA could not be
    accomplished because the log files only stored request information
    when it arrived or was sent from the web server. For each work
    request, two estimated times were added to the ones stored in the
    log files. These times were an average time to complete a work
    request screen and twice the average time it took for a packet to
    arrive from the PDA to the web server (network latency). These
    average times were computed for each screen in the PDA. The average
    time to complete each work request screen and the network latency
    were measured prior to the current test. The timeline for completing
    a work request is shown in Figure 5.

[]{#__RefHeading___Toc3092044 .anchor}Figure 5. Timeline for Work
Request Procedure

**[Error measures]{.underline}**

-   [Communication errors]{.underline}: These errors represented work
    requests that had to be partially or fully repeated. For the PDA,
    they also included work requests sent more than once.

```{=html}
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```
-   [Safety errors]{.underline}: These errors involved work
    authorizations accepted by the roadway worker without knowing the
    traffic pattern during the work period, work authorizations that
    were not cancelled when it was required, or work authorizations
    accepted in a location that was not the one requested.

```{=html}
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```
-   [Work requests that should have been sent but were not]{.underline}:
    The roadway worker had the opportunity to send the request, but for
    some reason he did not send it.

-   [Work requests that should not have been sent, but
    were]{.underline}: These were work requests that, because of traffic
    conflict, should not have been sent or work requests sent to the
    wrong dispatcher when using the radio.

[Situation Awareness]{.underline}

A set of questions used to measure situation awareness were administered
under two circumstances. Situation awareness was measured after the
participant requested information by voice radio from the dispatcher or
from the PDA. The first set was designed to measure the participant's
ability to retrieve information. Situation awareness was also measured
two times during each scenario when the participant had not requested
information. The second set was designed to examine the participant's
recall ability.

The questions assessed knowledge of the territory and train traffic at
or near the hypothetical work site, and were based upon a specific time
window. Territory information included dispatcher in charge, maximum
train speed, and operating rules that applied to the section of track
where the work took place. Train traffic patterns included the relevant
trains that affected the roadway worker during the time when the work
took place. For example, the roadway worker was queried about the train
ID, updated schedule, whether or not the train was delayed, and track
direction for trains that were supposed to pass through the work site
while the job was being performed. Scores were computed according to the
percentage of questions answered correctly. If the participant answered
all the questions about the current train schedule correctly, a score of
100 percent was given.

### Results and Discussion

#### Task Completion Time and Workload {#task-completion-time-and-workload .unnumbered}

Figure 6 shows the average time to complete each of the four
communication tasks. Participants took longer to request Form Ds and
Foul Time using the PDA compared to voice radio. The differences in both
these comparisons were statistically significant (t~n=30~ =4.14, p \<
0.0002 for the Form D comparison; t~n=24~ =6.28, p \< 0.0001 for the
Foul Time comparison). Form D requests averaged 3½ minutes with the PDA
and 2½ minutes with voice radio. Foul Time requests averaged 3 minutes
with the PDA and 1½ minutes with voice radio. In normal railroad
operations, Foul Time is less structured than a Form D and therefore
takes less time to request.

The device had limited two-way communications that resulted in longer
transaction times. When the dispatcher answered a work request, there
was no way to alert the roadway worker. The roadway worker had to
periodically query the system for a response from the dispatcher the
same way a person queries an e-mail server to obtain e-mail. If the
roadway worker waited too long before he or she checked for a response,
then the total work request time was also longer. With the next
generation of handheld devices, the dispatcher can alert the roadway
worker. These new devices will shorten transaction times.

The cancellation of work requests was shorter with the PDA than with
voice radio, but comparable to a Foul Time cancellation over the radio.
The Form D cancellation took longer over the radio because the formal
acknowledgment steps required the participant to repeat the main fields
of a Form D twice.

![](media/image10.wmf)

[]{#__RefHeading___Toc3092045 .anchor}Figure 6. Average Task Completion
Times

The transaction time comparisons measured between the two communication
modes in this study may not apply to the typical railroad operating
environment. In this study, the dispatcher played by the experimenter,
answered work requests as quickly as possible. In normal operations,
dispatcher response times vary. Dispatchers are often busy with other
tasks and do not answer requests right away. Overall, the participants
perceived the workload while using the PDA and the radio as being
similar. Half the participants said that workload was lower with the
PDA, while the other half said it was higher.

#### Error Analysis {#error-analysis .unnumbered}

Participants made fewer communications errors with the PDA compared to
voice radio, as shown in Figure 7. Although these results were not
statistically significant, the data suggests that presenting work
authorization information on a handheld visual display can reduce
communication errors associated with the acknowledgment process. This
result can be attributed to the reduced memory load associated with
information displayed visually. The participants filled in the same
fields continuously, and it was easy to remember a field since it was
displayed on the screen. A similar result occurred in an evaluation of a
visually based data link display for dispatchers (Malsch, Sheridan, and
Multer, 2004). In that study, fewer readback and hearback errors were
made with data link than with voice radio. Communication errors with the
PDA could have been reduced if the PDA had the ability to verify the
request before sending it to the dispatcher.

Participants made more than five times the number of safety errors with
voice radio than with the PDA. These differences were statistically
significant (χ^2^=6.87, df=1, p \< 0.01). Figure 7 shows that there were
11 safety errors with voice radio and only 2 with the data link device.

![](media/image11.wmf)

[]{#__RefHeading___Toc3092046 .anchor}Figure 7. Errors Associated with
Communications, Safety, and Work Requests

There were no significant differences between voice radio and the PDA
when submitting work requests that should not have been sent.
Participants submitted four work requests in the radio condition
compared to three in the PDA condition. While the average number of work
requests was the same for both communication modes (six per scenario),
participants made fewer requests than should have been sent with the PDA
as compared to voice radio. Figure 7 shows the number of work requests
that could have been sent, but were not. There were nine work requests
that could have been sent in the PDA condition compared to four work
requests in the voice radio condition. These differences were not
statistically significant. Taken together, the two work request measures
suggest that participants were more conservative in their willingness to
submit work requests when using the PDA.

#### Situation Awareness {#situation-awareness .unnumbered}

Overall, participants demonstrated better situation awareness scores
with the PDA than with voice radio. Participants answered 78 percent of
questions correctly in the PDA condition compared to 50 percent in the
voice radio condition. These differences were statistically significant
(x = 39.87, df=1, p \< 0.0001).

The same set of questions used to measure situation awareness was
administered under two circumstances. Situation awareness was measured
after the participant requested information by voice radio from the
dispatcher or from the PDA. The first set was designed to measure the
participant's ability to retrieve information. Situation awareness was
also measured two times during each scenario when the participant had
not requested information. The second set was designed to examine the
participant's recall ability.

In the first set of measures, participants exhibited better situation
awareness scores in the PDA condition. Participants answered 78 percent
of the questions correctly in the PDA condition, compared to 48 percent
in the voice radio condition. These differences were statistically
significant (x = 41.03, df=1, p \< 0.0001). The second set of situation
measures showed the same tendency. Participants answered 71 percent of
questions correctly in the PDA condition, compared to 50 percent in the
voice radio condition. However, the differences in the second set were
not statistically significant.

Compared to voice radio, the data link device resulted in safer
operations from two different points of view. First, situation awareness
scores were higher using the PDA device compared to voice radio.
Considering the train location and territory information that a roadway
worker must collect before starting work on the right-of-way, the
participants retrieved more information using the PDA device.

Figure 8 shows the five categories of information measured and Table 4
describes the categories of information collected. In four of the five
information categories, participants retrieved more information when
they used the data link device. The differences for three of these
measures were statistically significant: relevant trains, updated train
schedule, and train direction (x = 21.00, df=1, p \< .0001; x = 37.33,
df=1, p \< .0001; x = 21.00, df=1, p \< .0001 respectively).

![](media/image12.wmf)

[]{#__RefHeading___Toc3092047 .anchor}Figure 8. Information Retrieved

For all three measures, participants correctly answered the questions
100 percent of the time. With the voice radio, participants' answers
were correct between 50 percent and 60 percent of the time. When the
participants used the PDA, they identified almost all the trains that
could represent a hazard, but only 61 percent of the participants could
identify potential hazards when voice radio was used. Participants also
demonstrated better understanding of the actual train schedule when the
PDA was used.

When the roadway workers communicated by voice radio they could call the
dispatcher for updates, but most did not take advantage of this
opportunity. This behavior is consistent with their experience in
revenue service as roadway workers avoid calling the dispatcher with
this type of request. Roadway workers usually determine train status by
calling station staff or other track crews. Participants indicated that
the dispatcher was the last person they would call for train status
because of the dispatcher's high communication workload. They also
avoided calling dispatchers with simple requests.

  --------------------------------- ---------------------------------------------
  []{#__RefHeading___Toc527520625   
  .anchor}Table 4. Situation        
  Awareness Categories              

  **Measure**                       **Description**

  Territory Information             Includes dispatcher in charge of the
                                    territory, applicable operating rules, and
                                    the maximum train speed at the work site.

  Relevant Trains                   All trains that represented a potential
                                    hazard for the work crew.

  Updated Train Schedule            Knowledge of the real time train schedule.

  Train Delay                       Is the train delayed or on-time?

  Train Direction                   Direction of the train: east or west.
  --------------------------------- ---------------------------------------------

Although the information for updated train schedules and train delay
were similar, performance for these two categories differed
considerably. Participants exhibited better situation awareness scores
on the PDA for "updated train schedule" than for "train delay." This may
be due to the implementation of these two types of information on
separate screens. Knowledge of the train delay means the user also knows
the updated train schedule, but not deviation from the schedule. When
using the PDA, participants had no access to printed schedules that
could be used for reference. The information found in the PDA contained
updated times but the train delay had to be retrieved in a specific
screen that was viewed infrequently. Several participants suggested that
information about train status should be integrated with information
about train schedule on the PDA. Had this integration been included in
the PDA prototype, participants using the device might have performed
similarly in the two conditions.

#### User Acceptance {#user-acceptance .unnumbered}

Participants were asked if they would use the PDA in their jobs.
Interest was high for both requesting information and work
authorizations. The PDA application was rated on a scale from one to
five with one being the maximum acceptance and five being the minimum
acceptance. Participants gave the PDA a rating of 1.2 for retrieving
train location information and a 1.5 for asking the dispatcher for
protection. The participants' attitudes suggest roadway workers were
eager to use a handheld device like the one tested in this study.

Participants liked the fact they learned to operate the device with
minimal training. Three of the users asked if it would be used in
railroad operations and whether they would get a PDA. Almost all of the
participants saw other potential uses as discussed below. As one roadway
worker said, "\[The PDA\] is an excellent tool for employees working
both on the right-of-way and on trains."

#### Required Features {#required-features .unnumbered}

Despite the positive feedback for the use of a PDA in railroad
operations, the participants mentioned several features the device must
have before introducing it in revenue service. The criteria can be
divided into two categories: hardware and software.

[Hardware]{.underline}

-   The device must be rugged enough to withstand the conditions typical
    of the railroad environment. In particular, it must be waterproof
    and shockproof. A clip for attaching it to the roadway worker\'s
    belt and a hardcover for protection would also be helpful.

-   The screen should be larger (as much as twice the size of the
    current prototype) and the device should be able to do a
    self-diagnostic test to assure screen accuracy (i.e., to find
    malfunctioning pixels that may cause incorrect readings).

-   The device must be able to withstand being dropped.

-   The battery life should last at least one full day.[^3]

-   The wireless coverage should span the entire right-of-way and its
    surroundings. Participants were concerned about this issue because
    of their experience with inadequate coverage using cellular phones
    along the right-of-way.

-   The wireless device should allow two-way communications so warnings
    could be received by the PDA.

-   The PDA should also warn the user about approaching trains whenever
    they entered a block close to their working sites.

[Software]{.underline}

-   The system must keep a log of work permissions. NORAC rules require
    that fulfilled and canceled Form Ds must be kept for 7 days. Roadway
    workers usually keep a log of their Foul Time requests, and the PDA
    could benefit them by storing this log.

-   The system should not allow the dispatcher to grant work permission
    with different information from that initially requested by the
    roadway worker since this may cause a safety hazard (i.e., the
    system should not let the dispatcher grant work permission on Track
    1 if the roadway worker requested permission to work on Track 2).

-   Security features are needed so that only authorized users can use
    the application. A mechanism is also needed to authenticate the
    identity of the sender.

-   As a safety measure, the train schedule database must include all
    the trains (scheduled and unscheduled) under the control of the
    traffic center.

-   Information about train location should also be updated in real
    time.

One issue that spans both hardware and software is the need for security
to ensure that only authorized employees are able to communicate using
the application. Authentication procedures are also needed to ensure
that users know with whom they are communicating.

#### Optional Features {#optional-features .unnumbered}

Optional features for the device have been divided into three groups:
improvements with respect to features that already exist in the
prototype, new features to be added, and hardware improvements.

[Improvements to Existing Features]{.underline}

-   The software should be flexible enough to allow the roadway worker
    to ask for all types of work requests. The prototype only reflected
    three lines of a Form D when there were actually 13. Some of these
    lines were used often and should be included in an improved device.
    Work requests should be more flexible in terms of the ability to
    describe the desired work site. This includes the ability to ask for
    more than one track at a time (useful when requesting to foul an
    entire interlocking), and the ability to define work sites by
    mileposts as well as location names.

-   Before giving any section of track back to the dispatcher, the
    system should prompt the roadway worker for confirmation. The PDA
    should provide confirmation that permission to work is no longer in
    effect. The confirmation process should also address the unlikely
    situation where two work authorizations are in effect, and only one
    is cancelled.

-   The PDA could enhance the train status report by including the
    number of passengers or empty seats on passenger trains, the number
    of empty or loaded cars in freight trains from foreign railroads,
    and the reason for a train delay. Including this information offers
    the opportunity to speed up the movement of information for tracking
    business-related functions compared to paper-based methods.

-   Another beneficial feature to the device would be a quick reference
    to rules and rule updates and a description of equipment changes
    (such as moved signals, energized sections, and signals out of
    service) linked to the territory information report.

-   The PDA should also provide a visual alert screen to indicate if a
    train is late, or to indicate changes in train schedule. The updated
    and revised schedule could be shown on a separate screen. The PDA
    prototype always displayed updated times, but without the initial
    paper schedule it was not easy to tell whether a train was late or
    not. The PDA provided this information, but on a different screen
    (Train Status) and it was not merged with the updated times. Roadway
    workers commented that when the updated time was displayed, the time
    itself was not enough. The updated screen should also include a
    letter or a symbol indicating whether or not this time corresponded
    to the timetable schedule.

-   The device parameters should allow the PDA user to view all work
    permissions in effect for each track section on screens indicating
    the track that is out of service. It would also be beneficial to
    include work permissions under the authority of other roadway
    workers.

-   Finally, the device should allow easy access to information about
    special trains. The prototype design required that the user scroll
    through several different screens in order to reach the desired
    information. The existing PDA needs to be modified so that access to
    information is quick and easy.

[New Features]{.underline}

-   A valued addition to the PDA would be to include movement
    authorities such as Rule 241, as well as interactions with
    dispatchers for speed restrictions.

-   Important information such as weather conditions in different
    sections of the track could also be incorporated.

-   The device could be used to receive information concerning any
    situation that would affect the safe movement of trains or their
    time performance (i.e., train speed restriction bulletins,
    derailments, location of work crews or contractors on or fouling the
    track, blocks occupied, and over dimensioned cars).

-   Roadway workers would benefit if communication capabilities were
    extended to enable PDA users to send and receive short messages
    among themselves.

[Hardware Improvements]{.underline}

-   Participants were asked about the need for a portable wireless
    printer to make paper copies of specific screens on the PDA. The
    original idea was to print train schedule reports and work
    permissions. Some participants were enthusiastic about the idea
    while others thought it would be a burden.

#### Additional Uses {#additional-uses .unnumbered}

-   The participants in this study were conductors, so their duties
    often involved working on passenger trains. They mentioned the
    potential that a data link device might have while working on board
    trains. It would be useful as an alternative medium to communicate
    with management in stations or engineers while the conductor is on
    the train. It also could be used to give the passengers appropriate
    information about train connections or updated train schedule.

-   While the roadway workers are in the right-of-way, the PDA could be
    a good tool to communicate with other staff at the dispatch center
    such as the Trouble Desk Manager, to report speed restrictions.

-   During earlier tests, the PDA was demonstrated to the manager of
    operations for a passenger railroad. He observed great potential in
    real time train information and portable capabilities of the PDA to
    monitor the railroad network in and out of the office environment.

## Conclusions

The communication tasks of one class of roadway workers
(conductor-flagman) were evaluated as well as the information needed to
support those activities. The conductor-flagman serves as a conduit for
communications between roadway worker crews and dispatchers, and is
responsible for the safety of the work crew. Two types of tasks were
identified: acquiring information and requesting work authorizations.
The task of acquiring information included train status and information
related to the geographical territory (i.e., operating rules in effect).
The second task of requesting work authorization from the dispatcher was
classified according to whether the communications were structured or
unstructured. Structured communications consisted of transactions
defined by railroad operating rules. These include the exchange of
movement authorities and track work authorization. Unstructured
communications lack the formal procedures that make the structured
transactions predictable and time consuming.

An application was developed to support these communications-related
tasks on a wireless handheld computer. The key user information
requirement consisted of timely information about the train status with
respect to location and time. Work authorization procedures were
included to address the dispatcher's task requirements. The work
authorizations were representative of structured transactions between
dispatchers and roadway workers. The PDA provided the roadway worker
with current information about the status of the surrounding work area.
The PDA also enabled the roadway worker to request a variety of work
authorizations (Form D and Foul Time).

A text-based interface was developed on a wireless handheld computer.
This tool was developed cooperatively with several conductor-flagmen and
classroom instructors for roadway worker protection. Several user
requirements were identified which drove the development of the user
interface. The most important user requirements related to device size,
data entry, and ease of learning. The device had to be small enough to
be carried on the body, which also limited the available display space.
A PDA was chosen, which was smaller than a laptop display, but larger
than a cell phone display. Data entry had to be minimal, and the device
simple to learn. Interaction with the PDA was accomplished using a
stylus and a menu driven interface.

After developing an initial prototype, and conducting an informal
usability test and revising it, a formal usability test was conducted to
evaluate the device's readability and navigation. Overall, participants
found the device easy to read and navigate. Several participants were
looking forward to using such a device in their jobs. One drawback with
the current prototype was the slow data transmission speed for wireless
communications. This problem is a typical one for wireless applications
being used in the field in the early 21^st^ century, and it may impact
the acceptance of the device in the workplace. Lack of consistent
coverage in the field is another problem that may also affect usability
and user acceptance in the short term. Slow transmission speeds will
improve as better technology becomes available, and coverage will
improve over time as wireless service providers widen their networks.

Following the usability tests, performance between the PDA and voice
radio was compared for a variety of tasks. Task completion time, errors,
and situation awareness were measured. When requesting Form Ds or Foul
Time, completion times were longer for the PDA compared to voice radio.
This performance can be partly attributed to the slow response time
associated with wireless network and limitations of the user interface.
The improved performance in the voice radio condition could be
attributed to one specific artifact of this experiment. The dispatcher,
who was being played by the experimenter, always responded to incoming
messages as quickly as possible. In normal operations, the roadway
worker may wait a considerable length of time (e.g., several minutes)
before the dispatcher responds.

The prototype used in this study provided more accurate communications
than voice radio. There were fewer communication and safety-related
errors. A data link device capable of receiving time sensitive
information about train location improved roadway workers' situation
awareness scores and contributed to better decision-making processes in
a laboratory setting. User requests for track protection were more
consistent with the track availability. This benefits the dispatcher by
reducing the communication load and lowering the number of errors
associated with the acknowledgement procedures.

### Future Directions for Research

The two groups of tasks supported by the PDA represent only the
beginning in the evolution of digital communications and the development
of information appliances for roadway workers. More work is needed to
make the current prototype suitable for use in the field. A variety of
user interface issues common to all wireless handheld devices need to be
addressed. Two key issues include providing adequate display space and
improving methods for interacting with the device. The current user
interface is text based; however, roadway workers are comfortable
viewing maps that spatially show information on the track. Presenting
train status and territory information in a graphical format may enable
workers to quickly and effectively retrieve information. Usability
testing will be needed to answer this question.

The PDA addressed the roadway workers need to acquire information
without contacting the dispatcher. However, the current prototype lacks
the ability for true two-way communication in which the roadway,
dispatcher, or computer system can initiate communications. The device
relied upon the roadway worker to initiate communication. When a change
in the system occurs, the dispatcher cannot alert the roadway worker to
the change. Likewise, the dispatcher cannot send a signal to the roadway
worker to indicate the status of a work authorization request. The
roadway worker must initiate any action to request information or submit
a work authorization. A digital communication system with true two-way
communications could improve safety by enabling the dispatcher or
computer system to send warnings to the appropriate work crew when
relevant events occurred. A PDA with this capability is examined in the
next phase of this research.

Roadway workers who were interviewed for the current study proposed
making information currently found in paper form (an electronic
briefcase) available on the PDA. While some roadway workers may find the
current application useful, other tasks involving railroad operations
may need to be supported by the PDA application as well. Track foremen
and others who operate track equipment may have different or additional
information requirements to complete their tasks than conductor-flagmen.

As new technology becomes available, there is potential for improvement
in railroad operations. One technology that will improve safety and
productivity is GPS (global positioning system). As part of a
communications system, GPS can provide precise information concerning
the location of trains, track crews, and other railroad equipment. The
next study in this research program will evaluate the use of GPS to
provide track crew location information to dispatchers.

#  PDA System Architecture {#pda-system-architecture .Appendix-1}

## Components {#components .Appendix-2}

As shown in Figure 2, the prototype developed in this project is based
on the Internet, and has the following components:

1.  **[PDA device]{.underline}**. The prototype runs on a small
    information appliance called a Palm VII (Palm Inc, 1999; Palm Inc,
    2001a, Palm Inc, 2001b). It stores the web pages that are used to
    send requests to the dispatcher or the dispatcher's terminal. These
    web pages are designed in such a way that user interaction is
    minimized and simplified.

2.  **[Web server]{.underline}**. This server hosts the master files
    that are used as templates to send information back to the PDA.

3.  **[Query servers]{.underline}**. Run on the same computer as the web
    server and they are continuously looking for requests sent by the
    PDA or the dispatchers. These servers are responsible for
    redirecting the request to the appropriate destination.

4.  **[Database]{.underline}**. The prototype version is a static
    database but it is ready to be dynamically updated with real time
    data. This database stores information about past train schedules,
    expected schedules in the future, current delay, train information
    (direction of travel, number of cars, engine number), out of service
    track under Form D, out of service track under Foul Time, and
    territory information (maximum speed, dispatcher in charge, rules
    that apply)

5.  **[Dispatcher interface]{.underline}**. A very schematic message
    console for the dispatcher. This is where the dispatcher receives
    and answers requests sent to him by the PDA.

6.  **[Database manager interface]{.underline}**. A simple web page that
    is used to update the database.

### PDA Application {#pda-application .Appendix-3}

The prototype runs on a Palm VII, a device with wireless access to the
Internet. For details about how this wireless access is implemented,
refer to Palm VII white paper web page Palm, Inc. (1999). The Palm VII
is only online when it sends data and it only waits for incoming data
after the operator has sent a request. The Palm VII is limited by the
fact that it will not receive data until it first requests it. Several
design decisions were made because of this limitation. The application
only hosts web pages that do not change over time, and are only used to
submit requests to the server.

As shown in Figure A-1 to Figure A-4, the main menu is divided in three
submenus. One of the figures refers to train location and territory
information, and the other two refer to work requests (Form D or Foul
Time).

From the train and territory information submenu, the operator can
access train status information, territory information, and real time
train schedule. Following the link "Train Status," a roadway worker can
retrieve information for a given train which may include its current
delay, last location and time at that location, next location and
expected time at that location, destination, number of cars, and the
engine number. Following the link "Territory Information," for a given
section of the track the roadway worker can learn about maximum train
speed, dispatcher in charge of that territory, and rules that apply. The
roadway worker can retrieve real time train schedule, or train out of
service (OS) from two perspectives. Following the link "Train OS (ID),"
for a given train ID the roadway worker can obtain the train OS from the
beginning of its journey. Following the link "Train OS (work site)," for
a given section of the track and window of time the roadway worker can
obtain a list of trains that occupy or are expected to occupy the track
during that period.

+-----------------+-----------------+-----------------+-----------------+
| ![](me          |                 |                 |                 |
| dia/image13.png |                 |                 |                 |
| ){width="1.2395 |                 |                 |                 |
| 833333333333in" |                 |                 |                 |
| height="1.23958 |                 |                 |                 |
| 33333333333in"} |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| My Form D's     | My Foul Time    | Clear           | Cancel/Fulfill  |
+-----------------+-----------------+-----------------+-----------------+
| ![](med         | ![](med         | ![](med         | ![](med         |
| ia/image14.png) | ia/image15.png) | ia/image16.png) | ia/image17.png) |
| {width="1.25in" | {width="1.25in" | {width="1.25in" | {width="1.25in" |
| h               | h               | h               | h               |
| eight="1.25in"} | eight="1.25in"} | eight="1.25in"} | eight="1.25in"} |
+-----------------+-----------------+-----------------+-----------------+
|                 |                 | ![](med         | ![](med         |
|                 |                 | ia/image18.png) | ia/image19.png) |
|                 |                 | {width="1.25in" | {width="1.25in" |
|                 |                 | h               | h               |
|                 |                 | eight="1.25in"} | eight="1.25in"} |
+-----------------+-----------------+-----------------+-----------------+

[]{#__RefHeading___Toc3092048 .anchor}Figure A‑1. PDA Screen Shots (1)

  ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- -----------------------------------------------------
  ![](media/image13.png){width="1.1597222222222223in"                                                                                                                                                                                                                           
  height="1.1597222222222223in"}                                                                                                                                                                                                                                                

  Train Status                                                                                                Train OS (work site)                                  Train OS (ID)                                                                                               Territory Info

  ![](media/image20.png){width="1.1597222222222223in"                                                         ![](media/image21.png){width="1.1597222222222223in"   ![](media/image22.png){width="1.1597222222222223in"                                                         ![](media/image23.png){width="1.1597222222222223in"
  height="1.1597222222222223in"}                                                                              height="1.1597222222222223in"}                        height="1.1597222222222223in"}                                                                              height="1.1597222222222223in"}

  ![](media/image24.png){width="1.0798611111111112in"   ![](media/image25.png){width="1.0798611111111112in"   ![](media/image26.png){width="1.1597222222222223in"   ![](media/image27.png){width="1.0895833333333333in"   ![](media/image28.png){width="1.0798611111111112in"   ![](media/image29.png){width="1.1597222222222223in"
  height="1.0798611111111112in"}                        height="1.0798611111111112in"}                        height="1.1597222222222223in"}                        height="1.0895833333333333in"}                        height="1.0798611111111112in"}                        height="1.1597222222222223in"}

                                                        ![](media/image30.png){width="1.1597222222222223in"                                                                                                               ![](media/image31.png){width="1.1597222222222223in"   
                                                        height="1.1597222222222223in"}                                                                                                                                    height="1.1597222222222223in"}                        

                                                        ![](media/image32.png){width="1.1597222222222223in"                                                                                                               ![](media/image33.png){width="1.1597222222222223in"   
                                                        height="1.1597222222222223in"}                                                                                                                                    height="1.1597222222222223in"}                        
  ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- -----------------------------------------------------

[]{#__RefHeading___Toc3092049 .anchor}Figure A‑2. PDA Screen Shots (2)

  ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- -----------------------------------------------------
  ![](media/image13.png){width="1.0798611111111112in"                                                                                                                                                                                                                           
  height="1.0798611111111112in"}                                                                                                                                                                                                                                                

  Request Form D Line 4                                                                                                                                             Request Form D Lines 2,3                                                                                    

  ![](media/image34.png){width="1.0798611111111112in"                                                                                                               ![](media/image35.png){width="1.0798611111111112in"                                                         
  height="1.0798611111111112in"}                                                                                                                                    height="1.0798611111111112in"}                                                                              

  ![](media/image36.png){width="1.0798611111111112in"                                                                                                               ![](media/image36.png){width="1.0798611111111112in"                                                         
  height="1.0798611111111112in"}                                                                                                                                    height="1.0798611111111112in"}                                                                              

  ![](media/image37.png){width="1.0798611111111112in"   ![](media/image38.png){width="1.0798611111111112in"                                                         ![](media/image37.png){width="1.0798611111111112in"   ![](media/image39.png){width="1.0798611111111112in"   
  height="1.0798611111111112in"}                        height="1.0798611111111112in"}                                                                              height="1.0798611111111112in"}                        height="1.0798611111111112in"}                        

                                                        ![](media/image40.png){width="1.0798611111111112in"   ![](media/image41.png){width="1.0798611111111112in"                                                         ![](media/image40.png){width="1.0798611111111112in"   ![](media/image41.png){width="1.0798611111111112in"
                                                        height="1.0798611111111112in"}                        height="1.0798611111111112in"}                                                                              height="1.0798611111111112in"}                        height="1.0798611111111112in"}

                                                                                                              ![](media/image42.png){width="1.0798611111111112in"                                                                                                               ![](media/image43.png){width="1.0798611111111112in"
                                                                                                              height="1.0798611111111112in"}                                                                                                                                    height="1.0798611111111112in"}
  ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- -----------------------------------------------------

[]{#__RefHeading___Toc3092050 .anchor}Figure A‑3. PDA Screen Shots (3)

+-----------+-----------+-------------+--------------+---------------+
| ![](me    |           |             |              |               |
| dia/image |           |             |              |               |
| 13.png){w |           |             |              |               |
| idth="1.1 |           |             |              |               |
| 597222222 |           |             |              |               |
| 222223in" |           |             |              |               |
| hei       |           |             |              |               |
| ght="1.15 |           |             |              |               |
| 972222222 |           |             |              |               |
| 22223in"} |           |             |              |               |
+-----------+-----------+-------------+--------------+---------------+
| Request   |           |             | Other Foul   | Track Outage  |
| Foul Time |           |             | Time         |               |
+-----------+-----------+-------------+--------------+---------------+
| ![](me    |           |             | ![]          | ![](media/im  |
| dia/image |           |             | (media/image | age46.png){wi |
| 44.png){w |           |             | 45.png){widt | dth="1.169444 |
| idth="1.1 |           |             | h="1.1694444 | 4444444445in" |
| 597222222 |           |             | 444444445in" | heig          |
| 222223in" |           |             | height       | ht="1.1694444 |
| hei       |           |             | ="1.16944444 | 444444445in"} |
| ght="1.15 |           |             | 44444445in"} |               |
| 972222222 |           |             |              |               |
| 22223in"} |           |             |              |               |
+-----------+-----------+-------------+--------------+---------------+
| ![](me    |           |             | ![]          | ![](media/im  |
| dia/image |           |             | (media/image | age48.png){wi |
| 36.png){w |           |             | 47.png){widt | dth="1.169444 |
| idth="1.1 |           |             | h="1.1694444 | 4444444445in" |
| 694444444 |           |             | 444444445in" | heig          |
| 444445in" |           |             | height       | ht="1.1694444 |
| hei       |           |             | ="1.16944444 | 444444445in"} |
| ght="1.16 |           |             | 44444445in"} |               |
| 944444444 |           |             |              |               |
| 44445in"} |           |             |              |               |
+-----------+-----------+-------------+--------------+---------------+
| ![](me    | ![](me    |             |              |               |
| dia/image | dia/image |             |              |               |
| 49.png){w | 50.png){w |             |              |               |
| idth="1.1 | idth="1.1 |             |              |               |
| 694444444 | 694444444 |             |              |               |
| 444445in" | 444445in" |             |              |               |
| hei       | hei       |             |              |               |
| ght="1.16 | ght="1.16 |             |              |               |
| 944444444 | 944444444 |             |              |               |
| 44445in"} | 44445in"} |             |              |               |
+-----------+-----------+-------------+--------------+---------------+
|           | ![](me    | ![](med     |              |               |
|           | dia/image | ia/image52. |              |               |
|           | 51.png){w | png){width= |              |               |
|           | idth="1.1 | "1.16944444 |              |               |
|           | 694444444 | 44444445in" |              |               |
|           | 444445in" | height="    |              |               |
|           | hei       | 1.169444444 |              |               |
|           | ght="1.16 | 4444445in"} |              |               |
|           | 944444444 |             |              |               |
|           | 44445in"} |             |              |               |
+-----------+-----------+-------------+--------------+---------------+

[]{#__RefHeading___Toc3092051 .anchor}Figure A‑4. PDA Screen Shots (4)

From the work request submenus, the roadway worker can request Form Ds
(line 4 or lines 2 and 3) and Foul Time. Following the links "My Form D"
or "My Foul Time," the roadway worker can retrieve a list of Form Ds or
Foul Time under his/her authority, and continue an interrupted work
request. Following the links "Cancel/Fulfill" or "Clear," the roadway
worker is able to give some track under his authority back to the
dispatcher. Following the links "Track Outage" or "Other Foul Time" the
roadway worker is able to determine for a given section of track whether
there is some track out of service under Form D or Foul Time.

### Web Server {#web-server .Appendix-3}

The web server is now running on a computer at the Volpe National
Transportation Systems Center.

### Query Servers {#query-servers .Appendix-3}

The query servers used in this study were mainly written in Java (Sun
Microsystems, 2001), and only one file was written in Perl (Clay, 2001).
The file used for this experiment is a Common Gateway Interface (CGI)
script, which is used as an interface between the web server and the
query servers. It reads the HTML forms as sent by the PDA, stores a file
with the request description (where the query servers are looking for
them), and finally reads and returns the requested information to the
PDA.

There were five query servers: database, dispatcher, file, dispatcher
terminal refresh, and simulation query servers. Every second, the
servers would look for requests sent by the PDA or dispatcher. When a
request arrived the appropriate query server read the request, processed
it, and wrote the answer for the CGI script to be sent back to the
original petitioner. A detailed description of the purpose of each
server follows.

1.  **Database Query Server**. Handles requests sent by the PDA that
    needs access to the train schedule database and the database updates
    sent from the database manager interface. These requests include:

> [Train Status]{.underline}: Receives a train ID as input and returns
> the status of that train. The train status includes for all trains:
> current delay in minutes, last location, next location, time at these
> two locations, destination, number of cars, and engine number.
>
> [Train OS (work site)]{.underline}: Receives a time window and a
> portion of track as input, and returns the real time train OS of all
> the trains that occupy that portion of track in the given time window.
>
> [Train OS (ID)]{.underline}: Receives a train ID as input and returns
> its real time train OS from the beginning to the end of its journey.
>
> [Territory Information]{.underline}: Receives a portion of track as
> input and returns the rules that apply in that territory as well as
> the dispatcher in charge, and the maximum train speed.
>
> [Update database]{.underline}: The database manager uses this request
> to manually update the delay of any train in the system. This request
> can also be used to reset the schedule of the trains. At the end of
> the day the train schedule is automatically reset to reflect the next
> day schedule, but should the database manager want to do it manually
> this request provides the option for him/her.
>
> [Update database from file]{.underline}: Automatic update of the
> database. This request is supposed to be triggered automatically every
> given time. It was included as an interface between a potential real
> time database and the PDA database.

2.  **Dispatcher Query Server**. Handles requests sent by the PDA that
    need dispatcher interaction such as requests that have to do with
    work permissions and answers sent by dispatcher to the PDA. These
    requests are:

> **Requests sent by PDA:**
>
> [Request Form D line 4]{.underline}: Used to send a work site
> description to the dispatcher, track number, and desired window of
> time to perform a work that will require a Form D line 4
> authorization.
>
> [Request Form D lines 2 and 3]{.underline}: Used whenever a roadway
> worker wants to operate a track car. This movement requires Form D
> lines 2 and 3 authorization. This request is used to send the
> dispatcher the portion of track, track number, and the direction of
> travel.
>
> [Ask for time effective or cancel Form D]{.underline}: A Form D is not
> active until the dispatcher assigns a time effective. Once the
> dispatcher has assigned a time effective, the Form D becomes a rule.
> Before this step, the roadway worker must acknowledge that the
> dispatcher has understood his/her request. The roadway worker then has
> to confirm the Form D by asking a time effective of the dispatcher.
>
> This request receives just the acceptance or rejection of the Form D
> as input. If the roadway worker accepts the Form D, the dispatcher
> will assign a time effective and it will become rule until it is
> cancelled or fulfilled. If the roadway worker rejects the Form D, the
> entire Form D request procedure will have to be repeated.
>
> [Retrieve list of active Form Ds:]{.underline} Used whenever a roadway
> worker has finished their job or wants to cancel or fulfill a Form D
> and is giving the track back to the dispatcher. This request will send
> the dispatcher a list of their active Form Ds and will let them select
> the one they want.
>
> [Cancel/fulfill Form D]{.underline}: Works together with the previous
> request. This is the step to actually cancel or fulfill the Form D.
>
> [My Form Ds]{.underline}: Used to retrieve a list of current Form Ds
> or incomplete Form D requests under the authority of the roadway
> worker holding the PDA. Although it is not included in the first
> prototype of the PDA, this request should also comply with rule 176,
> which states, "Form Ds which have been fulfilled or cancelled \[...\]
> must be retained and held available for inspection for a period of 7
> days" (NORAC operating rules).
>
> [Track outage:]{.underline} This feature is used to retrieve a list of
> track that is currently out of service under Form D authorization.
> Receives a portion of track as input, and for every section of track
> out of service within those given limits, it returns a list of track
> numbers and track owners. This knowledge will let the PDA user know
> whom they should contact in case they want access to that portion of
> track.
>
> [Request Foul Time]{.underline}: This feature is used to send the
> dispatcher a work site description, track number, and desired window
> of time to perform work that will require Foul Time authorization.
>
> [Accept or do not accept Foul Time]{.underline}: This is a roadway
> worker acknowledgement. This request receives just the acceptance or
> rejection of the Foul Time as input. If the roadway worker accepts the
> Foul Time, it will become active. If the roadway worker rejects the
> Foul Time, the entire Foul Time request procedure will have to be
> repeated.
>
> [Retrieve list of active Foul Time]{.underline}: Used whenever a
> roadway worker has finished their job or wants to clear a Foul Time
> and is giving the track back to the dispatcher. This request will send
> the roadway worker a list of his active Foul Times and will let them
> select the one they want.
>
> [Clear Foul Time]{.underline}: Works together with the previous
> request. This step is required to clear the Foul Time.
>
> [My Foul Time]{.underline}: Used to retrieve a list of current Foul
> Times or incomplete Foul Time requests under the authority of the
> roadway worker holding the PDA.
>
> [Other Foul Time]{.underline}: This feature is used to retrieve a list
> of track currently out of service under Foul Time authorization. It
> receives a portion of track as input, and for every section of track
> out of service within those given limits; it returns a list of track
> numbers and track owners. This knowledge will let the PDA holder know
> whom they should contact in case they want access to that portion of
> track.
>
> **Requests sent by dispatchers:**
>
> [New dispatcher (login)]{.underline}: This feature is used whenever a
> new dispatcher enters the system. This request receives a territory
> description and a password as input and it returns a full dispatcher
> terminal that will receive any request that has to do with the given
> territory. Dispatchers have to log into the system before they are
> able to receive requests from the PDA.
>
> [Answer request for Form D lines 2 and 3]{.underline}: Used by a
> dispatcher to grant or deny the requested Form D lines 2 and 3. If the
> dispatcher grants the Form D, they will send the roadway worker who
> made the request the appropriate information. This information
> includes Form D number (automatically assigned by system), Form D
> recipient, date, direction of travel, track number, track location,
> and information about trains or track cars ahead. In case the
> dispatcher denies the requested Form D, it will be cancelled and the
> roadway worker will be notified.
>
> [Answer request for Form D line 4]{.underline}: Used by a dispatcher
> to grant or deny the requested Form D lines 4. If the dispatcher
> grants the Form D, the appropriate information will be sent to the
> roadway worker who requested it. This information includes Form D
> number (automatically assigned by system), Form D recipient, date,
> track number, track location, and foreman in charge of the track out
> of service. In case the dispatcher denies the requested Form D, it
> will be cancelled and the roadway worker will be notified.
>
> [Assign time effective for Form D]{.underline}: Once the roadway
> worker has received and acknowledged the previous information for any
> Form D, the dispatcher assigns a time effective. The time effective is
> sent to the roadway worker and the dispatcher is notified of its
> receipt.
>
> [Answer request for Foul Time]{.underline}: Used by a dispatcher to
> grant or deny the requested Foul Time. If the dispatcher grants the
> Foul Time, the appropriate information will be sent to the roadway
> worker who requested it. This information includes track number, time
> issued, time allowed, employee in charge, and track location. If the
> dispatcher denies the requested Foul Time, it will be cleared and the
> roadway worker will be notified.

3.  **File Query Server**. Handles requests sent by the PDA or the
    dispatcher that only require reading a file or finding out whether a
    file exists.

These requests are:

> [Items in My Form Ds or My Foul Time reports]{.underline}: Form Ds and
> Foul Times are not stored in the PDA. They are stored in the machine
> running the web server. When a roadway worker wants to know about
> their own Form Ds or Foul Time, they use the PDA to retrieve it from
> the web server. The roadway worker will not look for the specific file
> name, they will only tell the PDA they want to retrieve a specific
> Form D number or a given Foul Time.
>
> [Wait screens]{.underline}: While the roadway worker or dispatcher are
> waiting for the other end to answer a request, a "please wait" screen
> lets the user know. Since the Palm VII has no way to receive
> information until it has asked for it, this "please wait" screen has a
> button the roadway worker will use to check whether the answer is
> available or not. If the answer is available, it will be sent. If it
> is not available, an updated "please wait" screen will be sent. On the
> other hand, the dispatcher terminal (running in a standard web
> browser) has the ability to periodically check for answers from the
> PDA.

4.  **Dispatcher Terminal Refresh Query Server**. The dispatcher
    terminal must reflect in real time the current state of the work
    requests. This server is responsible for updating the information
    every 10 seconds.

5.  **Simulation Query Server**. Used to conduct the experiment, this
    server is responsible for sending the proposed tasks to the
    participants.

### Database {#database .Appendix-3}

The database includes information about dispatchers, roadway workers,
track (type of territory, dispatcher in charge, maximum train speed),
and trains (ID, schedule, engine number, number of cars, direction of
travel, and days run). For the purpose of the experiments, the database
also includes information about tasks to be done by test users and
initial delays for trains during the experiment.

Six types of text files are used to load the database. The data files
are tab separated text files. Following is a description of their
functionality and format.

[Dispatchers]{.underline} (dispatchers.txt). Includes the name of the
dispatcher, branch (not used), limits of the territory under his/her
authority (initial mile post and final milepost), a territory ID, and
the password needed during login.

Territory IDs are used internally by the query servers, and they must be
unique.

1.  [Roadway workers]{.underline} (MWForemen.txt). Includes information
    about registered PDAs and their owner.

2.  [Track information]{.underline} (Track Info.txt). Includes
    information about all the locations along the track (milepost,
    dispatcher in charge, maximum train speed, interlocking or station),
    the maximum number of parallel tracks, the rules that apply in each
    track between every two locations and whether each location is a
    control point or not. Control points or scheduled sites, will be the
    only locations sent to the PDA when a train OS is requested.

3.  [Schedule file]{.underline} (Boston-New Haven.txt) and (New
    Haven-Boston.txt). Includes information about scheduled trains (ID,
    schedule, engine number, number of cars, direction of travel, and
    days run)

**Dispatcher Interface**

Any web browser can serve as the dispatcher interface. After logging
onto the home page and selecting a territory, the user will be logged as
the dispatcher in charge of that territory. The system will show all the
incoming messages that affect the selected territory. Figure A-5 shows
the dispatcher interface.

![](media/image53.png){width="6.495138888888889in" height="3.84375in"}

[]{#__RefHeading___Toc3092052 .anchor}Figure A‑5. Dispatcher Interface

**Database Manager Interface**

When the system is running, any web browser can serve as the database
manager interface. From this page, a database manager can manually
update delays of the trains in the system.

Figure A-6 shows the database manager interface.

![](media/image54.png){width="4.095833333333333in"
height="3.279861111111111in"}

![](media/image55.png){width="4.095833333333333in"
height="1.4847222222222223in"}

[]{#__RefHeading___Toc3092053 .anchor}Figure A‑6. Database Manager
Interface

Type of Requests

**Master Files**

The system is designed to be highly configurable. To achieve this goal,
not all the information that is displayed to the dispatcher or sent to
the PDA is included in the source code of the servers. It is stored in
what is called the master files. The master files are just templates of
HTML files that are read by the servers and filled with the correct
information every time they are used.

# Questionnaires {#questionnaires .Appendix-1}

Following the ideas in Nielsen, (1994) and Kirwan, (1992) three sets of
questionnaires were prepared. These questionnaires were given to the
test users during the experiments.

The first set was a list of questions about background and demographics
of the test user. The second set was used during the usability test to
evaluate the last iterations of the PDA application design for specific
major problems and to measure the user's ability to complete the tasks
effectively. This questionnaire helped to identify points of confusion
and difficulty. The third set of questions was used during the system
evaluation test. It was used to validate the final PDA application
design, to check if it met minimum performance levels and to understand
its usefulness.

## Demographic Questionnaire {#demographic-questionnaire .Appendix-2}

![](media/image56.wmf){width="6.3590277777777775in"
height="7.104166666666667in"}

## Usability Questionnaires {#usability-questionnaires .Appendix-2}

![](media/image57.wmf){width="5.479166666666667in"
height="8.509722222222223in"}

![](media/image58.wmf)

![](media/image59.wmf)

![](media/image60.wmf)

![](media/image61.wmf)

![](media/image62.wmf)

## System Evaluation Questionnaire {#system-evaluation-questionnaire .Appendix-2}

![](media/image63.wmf)

![](media/image64.wmf)

![](media/image65.wmf)

## Situation Awareness Questionnaire {#situation-awareness-questionnaire .Appendix-2}

![](media/image66.wmf){width="6.5in" height="2.5729166666666665in"}

# Form D {#form-d .Appendix-1}

![](media/image67.png){width="5.841666666666667in"
height="7.882638888888889in"}

A brief explanation of the use of the different lines of a Form D
follows (see rules 160-173). The brackets indicate the rules that apply
for each line from the NORAC Operating Rulebook.

1 \[175\]: Speed restrictions. Train Speed Restriction Bulletins (TSRB)
are used in place of line 1.

2 \[400,402-405, 502, 803, 805, 806, 808\]: Direction of travel. Written
to give authority to track cars to operate on a specific track between
two interlockings.

3 \[803, 805, 806, 807\]: Written to inform track cars about trains or
track cars ahead. A track car is allowed to move behind trains, never in
front of them. The second part of line 3 is used to give permission to
pass a stop signal. Rule 241 is usually used in place of second part of
line 3. Some dispatchers use line 3 and not rule 241.

4 \[132-134\]: Track goes out of service. Another railroad employee
(i.e., flagman-conductor) is in charge of the track.

5 \[132, 135\]: Rebuild grade crossing without disturbing the track.
Just nearby road.

6,7 \[406\]: Form D Control System (DCS), Control Point (CP) (see rules
400).

8,9 \[137\]: Used when a rescue train is heading towards the train being
rescued.

10 \[174\]: Temporary Block Station.

11 \[561\]: Cab Signal System (CSS).

12 \[138\]: Used when a grade crossing malfunctions.

13 \[132, 177, 400, 404, 406, 506, 507, 805, 806\]: General purpose.
Used for example to describe where barricades are.

Dispatchers most frequently use lines 2, 3, and 4. Lines 2 and 3 are
issued to track cars and work extra trains. Line 4 is issued to repair
crew foreman, flagmen, and point conductors.

#  Palm VII Characteristics  {#palm-vii-characteristics .Appendix-1}

The Palm VII device was a member of the Palm family of handheld
organizers. Some of the features of the Palm VII included the following:

-   Pocket size: 5.25\" x 3.25\" x 0.75\" and lightweight: 6.7oz.

-   Built in wireless Internet connection with the following security
    measures: data encryption, secure sockets layer, and network
    authentication

-   Several weeks of battery life on two AAA batteries (depending on
    usage), and low battery indicator

-   Able to send and receive e-mail

-   No previous computer knowledge required. Works with a stylus that is
    used to tap on the screen and fill the requests without typing

-   Infrared port that could be used with a portable printer

Its weight and dimensions together with the wireless Internet capability
made this device ideal for data link communications with roadway
workers.

The main disadvantages of the Palm VII device were its fragility and the
fact that it couldn't receive information without first asking for it.
It had two-way communication capabilities but the communication had to
always start at the Palm VII side. Its fragility made the Palm VII
useless in tough environments such as the railroad. It didn't resist
rain or dust and it was hard to read under very sunny conditions. The
fact that it couldn't receive information without first asking for it
made the Palm VII device useless for receiving warnings (i.e.
approaching trains).

## Security and Authentication {#security-and-authentication .Appendix-2}

Roadway workers expressed major concerns for adequate security to
prevent unauthorized access. Roadway workers interviewed for this study
indicated that it would also be important to positively identify the
person communicating with the PDA by utilizing some form of password
protection.

The Palm VII incorporated several levels of protection. During the
wireless portion of the communication, the Palm VII used a cryptographic
technology developed by Certicom. According to a product white paper
(Palm Inc, 1999), \"Certicom's advanced elliptic curve cryptosystem
enables significantly shorter message sizes with the security strength
of their 163-bit keys. These keys are equivalent in strength to RSA
1024-bit keys, thus minimizing message lengths without sacrificing
security.\" During the server-to-server portion of the communication
between the Palm Computing Web Clipping Proxy and other servers, 128
bits secure socket layer (SSL) could be used. There were also other
levels of security such as network authentication and physical security
of the Palm Computing Web Clipping Proxy server.

Regarding authentication, again two different levels could be provided.
Each Palm VII device had a built in device ID that could be sent with
every message. This device ID was used to identify which roadway worker
was sending each request. In addition, messages from Palm VII devices
that were not registered with the system were ignored. Unregistered
users could retrieve train location information or submit a work request
to a dispatcher. The second level, which was not incorporated in the
prototype, was password-protected access to the system. A personal
password could have been required to communicate with the Traffic
Control Center.

# Glossary {#glossary .Executive-Summary}

**Block Signal:** A fixed signal displayed to trains at the entrance to
a block to govern use of that block. [^4]

**Block:** A length of track with defined limits on which train
movements are governed by block signals, cab signals, or Form D. ^1^

**Blocking device:** A lever, plug, ring, or other method of control
that restricts the operation of a switch or a signal. [^5]

**Cab signal:** A signal located in the engine control compartment that
indicates track occupancy or condition. The cab signal is used in
conjunction with interlocking signals and in lieu of block signals. ^1^

**Controlled track:** Track upon which the railroad's operating rules
require that all movements of trains must be authorized by a train
dispatcher or a control operator. ^2^

**Dark territory:** A section of track that is not signaled. In dark
territory, the train dispatcher does not get automatic indication of the
location of the trains, nor does the train get automatic signals
allowing movement through the territory. [^6]

**Data link:** Technology that enables information that is now
transmitted over voice radio links to be transmitted over data lines.
^3^

**Fixed signal:** A signal at a fixed location that affects the movement
of a train. ^1^

**Flagman:** When used in relation to roadway worker safety, means an
employee designated by the railroad to direct or restrict the movement
of trains past a point on track to provide on-track safety for roadway
workers, while engaged solely in performing that function. ^2^

**Foul Time:** Method of establishing working limits on controlled track
in which a roadway worker is notified by the train dispatcher or control
operator that no trains will operate within a specific segment of
controlled track until the roadway worker reports clear of the track.
^2^

**Fouling a track:** Placement of an individual or an item in such a
proximity to a track that the individual or equipment could be struck by
a moving train or on-track equipment, or in any case is within four feet
of the field side of the near running rail. ^2^

**Interlocking:** An interconnection of signals and signals appliances
such that their movements must succeed each other in a predetermined
sequence, assuring that signals cannot be displayed simultaneously on
conflicting routes. ^2^

**Movement Permit Form D:** A form containing written authorization(s),
restriction(s), or instruction(s) issued by the dispatcher to specified
individuals. [^7]

**On-track safety:** State of freedom from the danger of being struck by
a moving railroad train or other railroad equipment, provided by
operating and safety rules that govern track occupancy by personnel,
trains, or on-track equipment. [^8]

**Real time train OS:** Dispatcher's term that refers to train schedule
with time updates**.**

**Roadway worker:** Any employee of a railroad, or of a contractor to a
railroad, whose duties include and is actively engaged in the
inspection, construction, maintenance, or repair of railroad track,
bridges, roadway, signal and communication systems, electric traction
systems, roadway facilities, or roadway maintenance machinery on or near
the track. Also pertains to an individual with the potential of fouling
a track as well as employees responsible for their protection. ^1^

**Shunt:** Activate block or interlocking signals when present on track.
[^9]

**Track car:** Equipment other than trains, operated on a track for
inspection or maintenance. Track cars might not shunt track circuits.
^2^

**Train dispatcher:** Railroad employee assigned to control and issue
orders governing the movement of trains on a specific segment of
railroad track in accordance with the operating rules of the railroad
that apply to that segment of track. ^2^

# References {#references .Executive-Summary}

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[www.fra.dot.gov/o/counsel/regs/cfr/part/49CFR214v1.htm](http://www.fra.dot.gov/o/counsel/regs/cfr/part/49CFR214v1.htm)
\[March 12, 2001\].

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[www.palm.com/devzone/docs.html](http://www.palm.com/devzone/docs.html)
\[March 12, 2001\].

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International*, pp 69-77.

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Federal Railroad Administration. (1999). Paper presented at the John A.
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Federal Railroad Administration. (1994). *Railroad Communications and
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Transportation.

Kirwan, B. (1992) *A Guide to Task Analysis*. New York: Taylor &
Francis.

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Nielsen, J. (1994). *Usability Engineering.* San Francisco:
Morgan-Kaufmann.

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[www.palm.com/products/palmvii](http://www.palm.com/products/palmvii)
\[March 12, 2001\].

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[www.palm.com/pr/palmvii/7whitepaper.pdf](http://palm.com/pr/palmvii/7whitepaper.pdf)
\[March 12, 2001\].

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[^1]: Disturbing the track requires the dispatcher to remove it from
    service while the authorization is in effect.

[^2]: Locating the train by interlocking is important to Amtrak
    operations and may not be typical of other railroads.

[^3]: The batteries of the Palm VII easily lasted a few days but the
    transmitter had to be recharged after prolonged wireless
    transactions. The transmitter was fed from an intermediate energy
    storage element that was, in turn, charged from the batteries. When
    the energy storage element was being charged, the transmitter could
    not be used. This limitation is unacceptable in revenue service.

[^4]: ^14^ NORA operating rules

[^5]: ^25^ Roadway Worker Protection Manual (RWP manual)

[^6]: ^3^

[^7]: ^4^

[^8]: ^6^ Roth, E.M. and Malsch, N. 1999

[^9]: