Technology Implications of a 

Cognitive Task Analysis for 

Locomotive Engineers

U.S. Department 

of Transportation 

Federal Railroad 

Administration

 

 

Office of Research 

and Development 

Washington, DC 20590 

Human Factors in Railroad Operations

DOT/FRA/ORD-09/03 Final Report This document is available to the 

January 2009 public through the National Technical 

Information Service, Springfield, VA 22161 

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4. TITLE AND SUBTITLE

Technology Implications of a Cognitive Task Analysis for Locomotive Engineers 

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 EB101/RR04 

6. AUTHOR(S)

Emilie Roth and Jordan Multer 

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U.S. Department of Transportation 

Research and Innovative Technology Administration 

John A. Volpe National Transportation Systems Center 

Cambridge, MA. 02142-1093 

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Federal Railroad Administration 

Office of Research and Development 

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COTR: Dr. Thomas Raslear, Federal Railroad Administration 

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13. ABSTRACT (Maximum 200 words) 

This report documents the results of a cognitive task analysis (CTA) that examined the cognitive demands 

and activities of locomotive engineers in today’s environment and the changes in cognitive demands and 

activities that are likely to arise with the introduction of new train control technologies. The CTA combined 

structured interviews with experienced locomotive engineers, conductors, and trainers and direct observations 

made during head-end rides. Data were collected at seven sites, that included both passenger and freight 

railroads, including five locations where railroads were field testing advanced train control technologies. The 

results pointed to major cognitive challenges involved in operating a train, including the need for sustained 

monitoring and attention; maintaining an accurate situation model of the immediate environment (including 

the location, activities and intentions of other agents in the vicinity such as other trains and roadway 

workers); anticipating and taking action in preparation for upcoming situations; and planning and decision 

making, particularly in response to unanticipated conditions (e.g., person or object obstructing the track). 

Introduction of new train control technology reduces some cognitive demands while creating new ones. The 

report discusses implication of the results for design of in-cab displays and development of training, 

particularly for positive train control systems. 

14. SUBJECT TERMS

 Cognitive task analysis, communications, decision-making, human factors, locomotive engineer, 

positive train control (PTC), railroad operations, train handling, teamwork 

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1 inch (in) = 2.5 centimeters (cm) 1 millimeter (mm) = 0.04 inch (in) 

1 foot (ft) = 30 centimeters (cm) 1 centimeter (cm) = 0.4 inch (in) 

1 yard (yd) = 0.9 meter (m) 1 meter (m) = 3.3 feet (ft) 

1 mile (mi) = 1.6 kilometers (km) 1 meter (m) = 1.1 yards (yd) 

1 kilometer (km) = 0.6 mile (mi)

AREA (APPROXIMATE) AREA (APPROXIMATE) 

1 square inch (sq in, in2) = 6.5 square centimeters 

(cm2

) 

1 square centimeter (cm2

) = 0.16 square inch (sq in, in2) 

1 square foot (sq ft, ft2) = 0.09 square meter (m2) 1 square meter (m2) = 1.2 square yards (sq yd, 

yd2

) 

1 square yard (sq yd, yd2) = 0.8 square meter (m2) 1 square kilometer (km2) = 0.4 square mile (sq mi, mi2) 

1 square mile (sq mi, mi2) = 2.6 square kilometers 

(km2

) 

10,000 square meters (m2

) = 1 hectare (ha) = 2.5 acres 

= 4,000 square meters (m2 1 acre = 0.4 hectare (he) ) 

MASS - WEIGHT (APPROXIMATE) MASS - WEIGHT (APPROXIMATE) 

1 ounce (oz) = 28 grams (gm) 1 gram (gm) = 0.036 ounce (oz) 

1 pound (lb) = 0.45 kilogram (kg) 1 kilogram (kg) = 2.2 pounds (lb) 

1 short ton = 2,000 pounds 

(lb) 

= 0.9 tonne (t) 1 tonne (t) =

=

1,000 kilograms (kg) 

1.1 short tons

VOLUME (APPROXIMATE) VOLUME (APPROXIMATE) 

1 teaspoon (tsp) = 5 milliliters (ml) 1 milliliter (ml) = 0.03 fluid ounce (fl oz) 

1 tablespoon (tbsp) = 15 milliliters (ml) 1 liter (l) = 2.1 pints (pt) 

1 fluid ounce (fl oz) = 30 milliliters (ml) 1 liter (l) = 1.06 quarts (qt) 

1 cup (c) = 0.24 liter (l) 1 liter (l) = 0.26 gallon (gal) 

1 pint (pt) = 0.47 liter (l) 

 1 quart (qt) = 0.96 liter (l) 

1 gallon (gal) = 3.8 liters (l) 

1 cubic foot (cu ft, ft3) = 0.03 cubic meter (m3) 1 cubic meter (m3) 36 cubic feet (cu ft, ft3 = ) 

1 cubic yard (cu yd, yd3) = 0.76 cubic meter (m3) 1 cubic meter (m3) = 1.3 cubic yards (cu yd, yd3)

TEMPERATURE (EXACT) TEMPERATURE (EXACT) 

[(x-32)(5/9)] °F = y °C [(9/5) y + 32] °C = x °F

QUICK INCH - CENTIMETER LENGTH CONVERSION

0 1 2 34

Inches

Centimeters 01 3 26 1 4 5 7 1 1098 1 12

5

3

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 ii
 

Acknowledgements 

The Federal Railroad Administration’s (FRA) Office of Research and Development funded this 

research effort. We would like to thank FRA’s Office of Research and Development for the 

opportunity to perform and document cognitive analyses of train crew operations. We would like 

to thank Dr. Thomas Raslear, Senior Human Factors Program Manager, for his support and 

guidance. 

We would like to acknowledge a number of individuals who generously provided their time and 

support. We would like to thank Don Scott, General Manager Operations, Standards & 

Compliance & System General Road Foreman, National Railroad Passenger Corporation, for 

providing us the opportunity to interview Locomotive Engineers and training instructors at the 

Amtrak Training Center in Wilmington, DE; Alan Polivka, Communications & Train Control 

Technologies General Manager North American Joint Positive Train Control (NAJPTC) Project 

Transportation Technology Center, Inc.; and Dan Steinhoff, Union Pacific, for providing us the 

opportunity to ride a test train during one of the early NAJPTC field tests that was conducted in 

Bloomington, IL, on October 29, 2002, and sharing their insights. We would also like to thank 

Bob Kollmar, Amtrak, for providing us the opportunity to learn about the incremental train 

control system (ITCS) and the lessons learned from the system’s development and 

implementation. We are grateful to Bob for arranging for us to get a head-end ride on an ITCSequipped train and making available ITCS locomotive engineers to be interviewed in Chicago, 

IL, and Niles, MI. We would also like to thank John Vogler, New Jersey Transit, who provided 

us the opportunity to interview Advanced Speed Enforcement System (ASES) locomotive 

engineers. 

We would also like to acknowledge the national and local labor representatives of the 

Brotherhood of Locomotive Engineers (BLE) and the United Transportation Union (UTU). We 

especially want to thank Bob Harvey, Tom Pontolillo, and James Stem for communicating with 

their respective memberships in support of this project. The visible support of labor for this 

effort was important for reassuring the individuals that we interviewed that both labor and 

management was interested in their input and supported this work. 

Finally, we want to express our special thanks to all of the locomotive engineers and conductors 

who agreed to participate in the interviews and focus groups. Their candid comments and 

insights were critical to the success of this project. 

 iii
TABLE OF CONTENTS 

Exwcutive Summary....................................................................................................................... 1 

1. Introduction............................................................................................................................. 4 

1.1 CTA Objectives and Approach....................................................................................... 5 

1.2 Cognitive Functions and Processes Underlying Performance........................................ 6 

2. Methods .................................................................................................................................. 9 

3. Cognitive Demands and Performance Issues in Current Train Operations .......................... 12 

3.1 Train Crew Roles and Responsibility ........................................................................... 12 

3.2 KNowledge and Cognitive Functions involved in Operating a Train .......................... 14 

3.2.1 Developing and maintaining a situation model .................................................... 16 

3.2.2 Generating Expectations and Thinking Ahead ..................................................... 18 

3.2.3 Monitoring and Detection..................................................................................... 19 

3.2.4 Communication..................................................................................................... 21 

3.2.5 Planning and Decision-Making ............................................................................ 23 

3.2.6 Knowledge and Memory Demands ...................................................................... 28 

4. Impact of New Train Control Technologies on Cognitive Demands and Operating Practice

.............................................................................................................................................. 32 

4.1 Impact on Train Handling Strategies ............................................................................ 32 

4.2 Impact on Attention Allocation and Monitoring—Shifting Attention to ‘In-Cab’ 

Displays versus Out the Window ................................................................................. 35 

4.3 Improved Anticipation.................................................................................................. 36 

4.4 New Sources of Workload............................................................................................ 38 

4.4.1 Audio Alerts as a Source of Workload and Distraction........................................ 38 

4.4.2 Initialization/Interaction with PTC as a Source of Workload............................... 40 

4.5 Potential for Complacency............................................................................................ 40 

4.6 Need for Awareness of Mode Transitions .................................................................... 42 

4.7 Impact on Teamwork Processes.................................................................................... 44 

5. Implications for Introduction of New Train Control Technology ........................................ 45 

5.1 Design Implications ...................................................................................................... 45

5.2 Training Implications.................................................................................................... 46

References..................................................................................................................................... 48 

 iv
 

LIST OF FIGURES 

1. A simplified model of the knowledge, and high-level cognitive functions and processes that 

underlie cognitive performance .............................................................................................. 7 

2. Simplified model of the knowledge, and cognitive functions and processes that underlie 

locomotive engineer performance......................................................................................... 15 

3. Framework showing how informal cooperative processes across distributed teams build on 

and contribute to shared situation models and how the two combined can foster higher 

reliability performance and increased safety ........................................................................ 23 

4. ITCS In-Cab Display showing current speed and speed limit, next upcoming target speed 

limit, the distance to target, and a count down Time To Penalty (TTP)............................... 34 

5. ASES In-Cab Display ............................................................................................................... 36 

LIST OF TABLES 

1. New Train Control Technologies Examined ............................................................................ 10 

 v

 

Executive Summary 

Railroad operations in the United States are undergoing rapid changes. This includes 

introduction of faster trains, increased demands on track usage, and new train control 

technologies such as positive train control (PTC). As part of its efforts to investigate the safety 

implications of operational changes and emerging technologies, the Federal Railroad 

Administration’s (FRA) Office of Research and Development sponsored a series of Cognitive 

Task Analyses (CTA) to examine the cognitive and collaborative demands associated with 

different railroad operations positions. The first CTA focused on railroad dispatchers (Roth, 

Malsch, & Multer, 2001). A second CTA addressed roadway worker activities (Roth and 

Multer, in preparation). The present report documents the results of a CTA that was conducted 

to examine the cognitive and collaborative demands and activities of locomotive engineers. 

An important aim of CTA was to identify cognitive activities that could be supported more 

effectively through the introduction of advanced technologies such as PTC technologies that are 

currently being developed by the railroad industry and evaluated as a part of FRA research and 

development efforts. A second, related, aim was to anticipate new sources of cognitive demands 

and complexities that the new technologies might pose. Although PTC technologies have the 

potential to improve safety and efficiency of railroad operations, they also have the potential to 

create new failure modes and impose new cognitive demands on locomotive engineers who need 

to monitor PTC displays and provide inputs to the system. Part of the objective of CTA was to 

understand these potential new performance demands. 

While the report focuses primarily on the activities of the locomotive engineer, we recognize that 

train crews operating in the United States generally include two individuals, typically a 

locomotive engineer and a conductor. The report includes discussion of the interaction between 

the two individuals and how they work jointly to operate the train in a safe and efficient manner. 

The CTA was based on an extensive series of interviews and observations that were made at 7 

sites between February 2000 and September 2005. These sites included both intercity passenger 

operations, commuter operations and freight operations. Five of the sites were at locations 

where railroads were in the process of field testing advanced train control technologies. PTC 

systems we examined included communications-based train management (CBTM), advanced 

speed enforcement system (ASES), incremental train control system (ITCS), electronic train 

management system (ETMS), and North American Joint Positive Train Control (NAJPTC). 

The CTA identified the major cognitive functions that underlie locomotive engineer performance 

and the factors that contribute to cognitive challenges. Important cognitive functions include the 

need to maintain broad situation awareness and develop an accurate current situation model of 

the immediate environment (including the location, activities and intentions of other agents in 

the vicinity such as other trains and roadway workers); the need to generate expectations and 

think ahead so as to know where to focus attention, prepare for anticipated actions, as well as 

plan for contingencies; the need to actively engage in sustained visual and auditory monitoring, 

including monitoring radio communication; the need to manage multiple demands on attention; 

the need to prioritize and manage multiple goals; and the need for rapid decision-making in 

response to unanticipated conditions (e.g., a person or object obstructing the track). 

Complicating factors/challenges include poor visibility, missing and obscured signs, dynamically 

 1 
changing conditions (e.g., temporary speed restrictions and work zones), multiple demands on 

attention, and delays and reroutes that interfere with the ability to anticipate and prepare for 

upcoming events. 

 Experienced locomotive engineers have developed knowledge and skills that allow them to 

operate safely and efficiently. These include strategies for obtaining the information required to 

form an accurate model of the current situation and maintain broad situation awareness (e.g., by 

listening in to radio communications directed at others). This allows them to anticipate upcoming 

events and prepare for contingencies. They have also developed train handling strategies that 

allow them to rapidly assess and adapt to locomotive and consist characteristics, the terrain, and 

the automated train control technologies. These include strategies for operating the train 

efficiently and maintaining the train schedule as well as strategies for detecting and responding 

to emergency situations (e.g., a broken rail; switch in wrong position; or a person or object 

obstructing the track). 

The interviews and observations that we conducted at sites where new train control technologies 

were being introduced revealed that while these new technologies reduced some cognitive 

demands (e.g., some systems reduce memory demands by presenting work zone locations and 

temporary speed restrictions on in-cab displays), they also create new ones. These new cognitive 

demands, in turn, can lead to changes in how locomotive engineers operate the train. Sources of 

new cognitive demands include constraints imposed by the PTC braking profile that require 

locomotive engineers to modify train handling strategies; increases in information and alerts 

provided by the in-cab displays that require locomotive engineers to focus more attention on incab displays versus out the window, and requirements for extensive interaction with the PTC 

systems (e.g., to initialize it—to acknowledge messages and alerts) that impose new sources of 

workload. Although PTC technology is likely to have a positive impact on overall risk of 

accidents, these new sources of cognitive demand can contribute to errors and accidents (c.f., 

Wreathall et al., 2007). 

Railroads and PTC system designers need to be made aware that measures can be taken in the 

design of PTC displays and in development of user training to improve train crew performance 

and reduce the potential for human error. The final section of this report discusses a number of 

suggestions for ways to improve in-cab displays to reduce cognitive demands on train crews and 

facilitate train crew performance as well as suggestions for improved training. 

One promising area for research and development is improved in-cab displays that minimize the 

need to visually attend to the in-cab display to extract important information. It would be 

desirable to develop alternative display approaches for indicating to the locomotive engineer 

where train speed is in relation to the desired deceleration rate without having to closely monitor 

the visual in-cab display. Options to explore include the use of non-visual display modes, such as 

auditory or tactile displays. Heads-up displays, which would allow tracking critical driving 

parameters while still looking out the cab, may provide an alternative promising research 

direction. 

 2
 

A need also exists for improved training to support the introduction of new train control 

technologies. Training is needed to understand how the PTC system works (technical theory). 

Second, training is needed to understand how to operate the PTC system under different 

conditions (e.g., how to initialize it, what the different PTC displays mean, what error modes 

might arise, and what to do in those different conditions) and the applicable operating rulebook 

(PTC operations). Third, hands-on experience is required to reduce the attention demands 

associated with monitoring in-cab displays. A substantial learning curve exists to reach the point 

where the in-cab display does not serve as a source of distraction, diverting attention away from 

events out the window. Locomotive engineers must have sufficient experience in running a PTCequipped train as part of training so that they get beyond the point where close monitoring of the 

in-cab display is required to avoid a penalty brake application. Fourth, hands-on experience 

and/or simulator training is required to learn the new train handling and braking strategies 

required to operate a PTC-equipped train to run efficiently while staying within the PTC braking 

profile (hands-on train handling). Hands-on experience is also needed to learn how to handle the 

“traps”, challenging situations, and failure conditions that are known to arise in special 

circumstances. 

Finally, train crews must avoid too much reliance on the new train control technologies. In 

particular, it is important to continue to run the trains without the PTC system activated. 

Therefore, if the system ever fails, the engineer will still be able to operate the train safely. 

Two explicit limitations of the study should be noted. First, the PTC systems are described and 

analyzed as they were implemented at the time that site visits and interviews occurred (between 

2002 and 2005). In some cases the PTC systems have undergone substantial modification since 

that time. Second, in evaluating the impact of PTC technology on locomotive engineer 

performance, we assumed that no change in train crew configuration would occur. This was the 

stated operating philosophy at the time we conducted the study. The analysis provided in this 

report does not explicitly consider any additional sources of cognitive workload that may arise 

should there be a transition to single person operations. 

 3 
1. Introduction 

Railroad operations in the United States are undergoing rapid changes. This includes 

introduction of faster trains (e.g., high speed trains on the Northeast Corridor (NEC)), increased 

demands on track usage, and new train control technologies such as positive train control (PTC). 

As part of its efforts to investigate the safety implications of operational changes and emerging 

technologies, the Federal Railroad Administration’s (FRA) Office of Research and Development 

sponsored a series of Cognitive Task Analyses (CTA) to examine the cognitive and collaborative 

demands associated with different railroad operations positions. The first CTA focused on 

railroad dispatchers (Roth, Malsch, and Multer, 2001). A second CTA addressed roadway 

worker activities (Roth and Multer, in preparation). The present report documents the results of 

a CTA that was conducted to examine the cognitive and collaborative demands and activities of 

locomotive engineers. 

The purpose of the CTA of locomotive engineers was to understand the factors that complicate 

performance in today’s environment and the knowledge and skills that locomotive engineers 

have developed to cope with the cognitive and collaborative demands placed on them. The goal 

was to develop a knowledge base that can be used as a starting point to inform the design of new 

technologies, human reliability analyses, and policy issues that may arise. 

 A primary aim of CTA was to identify and document cognitively challenging aspects of the 

current work so as to anticipate potential impacts of new technologies on locomotive engineer 

performance as well as provide guidance for their design and introduction. Of specific interest is 

the introduction of PTC technology. Railroads in the United States and Canada are developing a 

variety of PTC systems that are intended to improve the safety of railroad operations. Their goal 

is to prevent train-to-train collisions and protect train crews and roadway workers. This is 

accomplished by providing backup warnings to train crews and by stopping trains that are about 

to: 

• Violate positive train separation (i.e., movement authority), 

• Exceed speed restrictions (including civil engineering restrictions and temporary slow 

orders), and 

• Enter track segments protected for roadway workers and their equipment operating under 

specific authorities. 

An important aim of CTA was to identify cognitive activities that could be supported more 

effectively through the introduction of advanced technologies such as PTC technologies that are 

currently being developed by the railroad industry and evaluated as a part of FRA research and 

development efforts. A second, related, aim was to anticipate new sources of cognitive demands 

and complexities that the new technologies might pose. Although PTC technologies have the 

potential to improve safety and efficiency of railroad operations, they also have the potential to 

create new failure modes and impose new cognitive demands on locomotive engineers who need 

to monitor PTC displays and provide inputs to the system. Part of the objective of CTA was to 

understand these potential new performance demands. 

While the report focuses primarily on the activities of the locomotive engineer, we recognize that 

train crews operating in the United States generally include two individuals, typically a 

locomotive engineer and a conductor. The report includes discussion of the interaction between 

 4
 

the two individuals and how they work jointly to operate the train in a safe and efficient manner. 

It also includes discussion of the interaction of the train crew with other railroad personnel 

outside of the train (e.g., dispatchers, employee-in-charge roadway workers; crews of other 

trains.) 

In evaluating the impact of PTC technology on locomotive engineer performance, we assumed 

no change in train crew configuration, since this was the stated operating philosophy at the time 

we conducted the study. The analysis did not explicitly consider any additional sources of 

cognitive workload that may arise should a transition to single person operations occur. 

Additional analyses would be needed to explicitly address the one-person operation case. 

The next two sections provide a general introduction to cognitive task analysis and the types of 

information about locomotive engineer performance that it attempts to capture. Section 1.1 

provides an introduction to cognitive task analysis methods and goals. Section 1.2 introduces a 

simplified model of the high-level cognitive functions and processes that underlie the cognitive 

performance of individuals and teams in natural work settings such as railroad operations. This 

model provided a guiding framework for eliciting and organizing the information that was used 

to analyze the knowledge and skills required of locomotive engineers and the factors that 

contribute to cognitive complexity. 

Section 2 describes the methodology that was used to conduct CTA including the specific 

railroad sites that were visited and systems that were included in the analysis. The results of 

CTA are presented in Sections 3 and 4. Section 3 provides an overview of the cognitive 

demands and performance issues in current train operations. Section 4 discusses the likely 

impact of new train control technologies on cognitive demands and operating practice. Section 5 

summarizes some of the key implications of CTA results for the introduction of new train control 

technology including design and training implications. 

1.1 CTA Objectives and Approach 

The need for a cognitive task analysis (CTA) arises from the changing nature of the locomotive 

engineer’s job over time. Since the beginning of railroad operations in the late 1800s to today, 

the locomotive engineer’s work has evolved from a physically demanding job to a cognitively 

demanding job. 

CTA methods have grown out of the need to explicitly identify and take into account the 

cognitive requirements inherent in performing complex work (Potter, Roth, Woods, and Elm, 

2000; Schraagen, Chipman, and Shalin, 2000; Bisantz and Roth, in press). A variety of specific 

techniques for knowledge acquisition have been developed that draw on basic principles and 

methods of cognitive psychology. These include structured interview techniques, critical 

incident analysis methods that investigate actual incidents that have occurred in the past, and 

cognitive field observation studies that examine performance in actual environments or in high 

fidelity simulators. 

While a variety of methods for performing cognitive task and work analyses exist, they share a 

common goal of providing information about two, mutually reinforcing perspectives. One 

perspective focuses on the fundamental characteristics of the work domain and the cognitive 

demands they impose. The other focuses on how current practitioners respond to the demands of 

the domain. This includes a description of the knowledge and skills practitioners have 

 5 
developed to operate effectively as well as any limitations in knowledge and strategies that 

contribute to performance problems. The results of a CTA reveal (1) the factors that contribute 

to cognitive performance difficulty; (2) the knowledge and skills that expert practitioners have 

developed to cope with task demands; and (3) opportunities to improve individual and team 

cognitive performance in a domain through new forms of training, user interfaces, or decision 

aids. 

The locomotive engineer CTA was performed based on a combination of structured interviews 

of individual and groups of locomotive engineers and conductors and field observations that 

included observations during head-end rides. Interviews and observations were performed in 

both passenger and freight territories. This included site visits to five territories where railroads 

were field testing advanced train control technologies. More details on the particular sites 

visited and groups interviewed can be found in Section 2. 

The primary purpose of CTA was to identify and document cognitively challenging aspects of 

the current work so to anticipate potential impacts of new technologies on locomotive engineer 

performance as well as provide guidance for their design and introduction. 

1.2 Cognitive Functions and Processes Underlying Performance 

A CTA captures the knowledge and high level cognitive functions and processes that underlie 

individual and collaborative performance in natural settings (Crandall, Klein, and Hoffman, 

2006; Klein et al., 2003). Examples of high level cognitive functions and processes include 

monitoring and detection, sense making, forming expectations, managing attention, planning, 

prioritizing and adapting plans as situations evolve. 

Figure 1 provides a simplified model of the high-level cognitive functions that underlie 

performance of people in natural settings. This model was used to guide the collection and 

interpretation of information as part of the CTA. In this section we provide an overview of the 

model and illustrate it in a simple everyday example. In Section 3.2, we use the model to 

characterize the cognitive activities that underlie locomotive engineer performance and the 

factors that create complexities and increase cognitive demands. 

 6
 

Active Information 

Processing 

Current Situation 

Model 

Knowledge and Skills 

(mental models, procedures, strategies) 

What to pay 

 attention to? 

Monitor/Detect Sense Making 

Communicate/Act 

Expectations 

Working Memory 

Long-term Memory 

Goals & Priorities 

Plan/Decide 

Coordinate 

Adapt & Re-plan 

World 

Figure 1. A simplified model of the knowledge, and high-level cognitive functions and 

processes that underlie cognitive performance 

An important driver of performance is the knowledge and skills that individuals have developed 

with experience that is stored in long-term memory that allows engineers to rapidly recognize 

and respond to situations. This includes facts, mental models (e.g., mental model of how 

physical systems work), and strategies and procedures for how to accomplish tasks. Knowledge 

from long-term memory is combined with information obtained from direct perception of the 

world (through monitoring and detection) to interpret what is observed and develop a situation 

model, which represents the current understanding of the situation. This process is referred to as 

sense making. For example, if you see a group of kids in costume going door-to-door down the 

street and it is Halloween you might interpret the situation as a group of trick-or-treaters. The 

situation model is then used to generate expectations that can guide attention (where should I 

look?), provide the basis for setting goals and priorities, making plans and decisions, and taking 

action (including communicating). In the trick-or-treaters example, you might generate the 

expectation that the kids will soon ring your doorbell and decide to bring candy over by the door 

to be ready for them. A hallmark of cognition in natural settings is the ability of people to 

reinterpret and adapt to changing situations. In the trick-or-treaters example, when you open the 

door, you might see that the kids are soliciting donations for a charity and are not trick-ortreating for candy. In that case, you would try to adapt to the situation and look for coins that 

you can give out to the kids instead of candy. 

Figure 1 provides a description of cognitive function at the macrocognition level (Crandall et al., 

2006). The emphasis is on describing people’s knowledge and strategies and how these are used 

to guide formation of expectations, development of plans, and adaptation of plans when events 

differ from expectations. 

 7 
Cognitive performance can also be characterized at a more microlevel, in terms of the elemental 

mental structures and processes involved from the point that external information is first detected 

by the sensory system until a response is produced by the motor system. For example, a 

microcognition description would provide a detailed characterization of how information moves 

across mental structures, such as sensory buffers and short tem memory stores and the detailed 

computational processes by which they are transformed. In Figure 1, this more detailed level of 

cognitive processing is represented by the arrows linking the “eye” icon (representing sensory 

processes), the box labeled “working memory,” representing information processing activities 

that occur in working memory, and the box labeled “long-term memory” that represents the 

processes by which information from long-term memory is activated and retrieved. 

Macrocognition and microcognition approaches provide complementary perspectives. 

Numerous attempts have examined the micro second-by-second information processing involved 

in driving a route. Examples include Luke, Brook-Carter, Parkes, Grimes, and Mills (2006) who 

employed eye tracking recordings to analyze the detailed visual scanning strategies used by 

locomotive engineers; Jansson, Olsson, and Erlandsson (2006) who used think-aloud protocols 

to examine the moment-by-moment attention and thinking processes as locomotive engineers 

drove a train route; Gillis (2005) who examined the detailed serial and parallel mental processes, 

and how they vary over the time course of a train trip; and Hamilton and Clarke (2005) who 

developed a computational model intended to predict locomotive engineer workload and 

performance time for different routes. 

The present CTA provides a more macrocognitive analysis of the performance of locomotive 

engineers. It provides a higher level picture of the contextual factors that impact performance 

and the cognitive and collaborative strategies that domain practitioners have developed in 

response to work demands. McLeod, Walker, and Moray (2005) have argued that this level of 

analysis is necessary to understand the critical factors that influence actual performance in a realworld, real-time, environment. This includes factors that contribute to error as well as factors 

that contribute high reliability performance and resilience in the face of unanticipated conditions 

(Hollnagel, Woods, and Leveson, 2006; Roth, Multer, and Raslear, 2006). 

A macrocognitive level of analysis can provide useful insights into the factors in today’s 

environment that pose challenges and create opportunities for error. It can point to opportunities 

for how new technologies could more effectively support performance. It also provides insights 

into aspects of the current environment that provide effective support and support functions that 

should be preserved as new technology is introduced. Existing approaches to analyzing and 

modeling driver performance based on microlevel information-processing models and 

hierarchical task decomposition do not capture these contextual and situational factors (Crandall 

et al., 2006; Klein et al., 2003). 

 8
 

2. Methods 

CTA was based on an extensive series of interviews and observations that were made at seven 

sites between February 2000 and September 2005. These sites included intercity passenger, 

commuter, and freight operations. 

Initial interviews and observations were conducted on Amtrak passenger trains in 2000. The 

objective was to obtain a high level overview of the knowledge, skills and cognitive demands 

associated with operating a train. A total of 11 locomotive engineers were interviewed that 

included: (1) training instructors and experienced locomotive engineers at the Amtrak Simulator 

Training Facility in Wilmington, DE; (2) locomotive engineers during head-end rides that were 

conducted on NEC signal territory, as well as unsignaled (dark territory) outside NEC. 

Topics covered during this initial series of interviews and observations included: 

• Training and knowledge requirements, 

• Activities conducted at a start of a shift and at shift turnovers, 

• Responsibility distribution and coordination when two people in the cab, 

• Cognitive demands, 

• Establishing priorities/managing workload, 

• Planning/decision making strategies (including train handling and braking strategies), 

• Radio communication, 

• Strategies for maintaining (situation awareness/knowing where you are), and 

• Fatigue/ways to respond to/cope with fatigue. 

A second series of interviews were then conducted that focused specifically on the introduction 

of advanced train control technologies and their potential impact on train operation. 

Interviews were conducted at five sites where railroads were testing or beginning to use new 

train control technology with elements of PTC. Table 1 lists the railroads and systems examined. 

The objective was to understand the perceived impact of the new train control technologies on 

how the locomotive engineers ran the trains, and whether any new human performance issues or 

sources of risk were associated with the use of these new systems. 

Topics covered included: 

• Required interactions with the system both during set up before a trip as well as during a trip, 

• The potential impact on distraction (attention allocation between information inside and 

outside the cab), 

• Impact on train handling and braking strategies, 

• Impact on workload and work mode transitions, 

• Training, 

• Complacency, 

• Support for look-ahead, 

• Impact on memory requirements (reliance on information in the head vs. on paper vs. 

integrated in the cab interface), and 

• Potential interaction with operating rules. 

 9 
Table 1. New Train Control Technologies Examined 

System Name Railroad 

Interview Date 

Groups Interviewed 

Communications Based Train 

Management 

CSX 

October 2001 

locomotive engineers, 

conductors, includes 

observations during head-end 

rides 

North American Joint PTC 

System 

Amtrak 

Union Pacific 

October 2002 

locomotive engineers, training 

instructors; includes 

observations during head-end 

rides 

Incremental Train Control System Amtrak 

October 2003 

locomotive engineers; includes 

observations during head-end 

rides 

Advanced Speed Enforcement 

System 

New Jersey 

Transit 

March 2004 

locomotive engineers, 

conductors 

Electronic Train Management 

System (ETMS) 

BNSF locomotive engineers, training 

instructors; includes 

observations during head end 

rides 

(Beardstown, IL 

Subdivision) 

September 2005 

Interviewees were recruited through contacts with railroad management and labor union 

representatives. Interviews were conducted with individuals or groups of up to five people 

representing a single craft. Typically two to four interviewers represented different behavioral 

research disciplines, including human factors engineering and human reliability analysis. One 

interviewer led the interview sessions using a set of predefined interview questions. The other 

interviewers took notes and asked occasional follow up questions. The predefined question set 

primarily served as a checklist of topics to be covered. Actual questions asked and their order 

varied depending on participant responses. 

Interviews lasted approximately 2 hours and were tape recorded with the knowledge and 

permission of the individuals who were interviewed. 

The tape-recorded interviews were transcribed and analyzed with the goal of identifying 

recurrent themes across interviews as well as specific actual incidents described by interviewees 

that illustrate the themes. 

The analysis focused on identifying: cognitive and collaborative demands in the current 

environment, which contribute to performance difficulties and errors; and skills and strategies 

that expert practitioners have developed to build and maintain shared situation awareness to 

avoid or catch errors and to improve efficiency and enhance safety. 

 10
 

As part of the analysis, common themes relating to the impact of the introduction of new 

technologies were also extracted. This included examination of new opportunities to enhance 

performance and/or improve safety through the introduction of new technologies, as well as 

concerns relating to potential new problems that could emerge with the introduction of new 

technologies. 

The interviews of locomotive engineers, relating to the impact of PTC technology, were 

conducted as part of a larger project that addressed the impact of PTC technologies on railroad 

personnel performance and reliability. That project included interviews with roadway workers 

and dispatchers as well as train crews. A more detailed description of the methods and results 

are reported in Wreathall, Roth, Bley, and Multer (2007). 

 11 
3. Cognitive Demands and Performance Issues in Current Train 

Operations 

This section describes the cognitive demands and activities of locomotive engineers as they 

relate to current train operations. Section 3.1 provides a general introduction to train crew roles 

and responsibility. Section 3.2 examines the cognitive functions that underlie locomotive 

performance and the factors that contribute to cognitive challenges including: 

• The need to maintain broad situation awareness and develop an accurate current 

situation model, 

• The need to generate expectations, to think ahead, to guide attention, and to prepare for 

anticipated actions as well as plan for contingencies, 

• The need to actively engage in sustained visual and auditory monitoring including 

monitoring radio communication, 

• The need to manage multiple demands on attention, and 

• The need to prioritize and manage multiple goals. 

Section 3.2 also covers the knowledge and skills that experienced locomotive engineers develop 

that allows them to operate safely and efficiently including train handling strategies that are 

adapted to locomotive and train consist1 characteristics, the terrain, and the automated train 

control technologies 

This section analysis focuses primarily on train crew roles and responsibilities in passenger train 

operations. In many cases, the same cognitive tasks apply to freight operations as well. Cases 

having significant divergence in roles, responsibilities, or cognitive demands experienced are 

explicitly noted. 

3.1 Train Crew Roles and Responsibility 

Train crew roles and responsibility vary between passenger and freight operations. 

3.1.1 Passenger Operations 

In Amtrak passenger train operations, a crew consists of a minimum of three employees: a 

locomotive engineer, a conductor, and an assistant conductor. The locomotive engineer operates 

the train and complies with signals and speed restrictions. The conductor is in charge of the 

train. He/she will insure that doors are closed and that it is safe to move. The assistant 

conductor assists with fare and ticket collection. In an emergency, he/she is responsible for 

passenger safety. 

Generally, two individuals, two locomotive engineers or an engineer and a conductor, are 

required in the cab. The primary exception arises on short runs of 6 hours or less in signal 

territory on the NEC. In those cases, a single locomotive engineer may operate the train. 

However, if three or more of the hours fall between midnight and 6 a.m., then operating rules 

require two people in the cab. Similarly, if the train goes through dark territory where train 

 

1

 A train consist means one or more locomotives coupled to rail cars. 

 12
 

control is accomplished via radio communication with the dispatcher, then two individuals are 

required in the cab. 

Passenger trains that require two individuals in the cab will typically use two locomotive 

engineers. They share responsibility for operating the train. The two engineers will usually 

arrange between themselves how long each will operate the train before relinquishing controls to 

the other engineer. They will typically divide it either by time or by distance. The individual 

who is not currently driving the train is required to remain vigilant. He/she still has 

responsibility to insure that all the rules, signals, and speed restrictions are complied with. 

Typically, both engineers will call out the signals as they approach them. In dark territory, the 

engineer, who is not operating the train, is responsible for communicating with the dispatcher 

and writing down track warrants. 

Responsibilities of the conductor on passenger trains include: 

• Communicating with the dispatcher, 

• Insuring the engineer complies with track warrants, 

• Repeating back track warrants verbally to the engineer , 

• Preparing to leave the station, the conductor reminds the engineer of the next speed 

restriction, 

• Coordinating with the engineer on where to stop the train so that the cars are on the platform 

(This is often done during the pre-brief conducted prior to the start of a run), 

• Informing the engineer that it is okay to go (leave the station), 

• Coupling and uncoupling cars, 

• Changing switch position, 

• Coupling hoses to take cars apart and put together, 

• Ticketing and primary responsibility for passengers, and 

• Communicating with dispatcher on issues associated with customer, passenger, revenue, lost 

baggage, food. 

On passenger trains, the conductor spends his/her time in the passenger cars. The conductor and 

engineer typically communicate via radio. When the train has an intercom, the conductor 

presses a button located at the end of the car, rather than use the radio. When the conductor 

pushes the button twice and a buzzer sounds in the cab it tells the engineer they are ready to go 

after making a station stop. In cases where the conductor is off the train (e.g., to control a 

manual switch), they can communicate via hand signals. Both the conductor and the engineer 

can communicate with the dispatchers. 

3.1.2 Freight Operations 

In U.S. freight operations, two individuals work in the cab; a locomotive engineer who is 

responsible for running the train, and a conductor who is in charge of the train. The conductor 

is in charge of the train consist and is responsible for any required manual control of switches. 

The conductor shares the workload and serves as a backup to detect and recover from errors. 

The responsibilities of the conductor include the following: 

• Handle radio communications, therefore relieving the locomotive engineer of this potential 

source of workload. 

 13 
• Provide reminders of temporary speed restrictions, work zones, and end-of authority blocks 

coming up. For example, the conductor would remind the locomotive engineer when the 

radio frequency changed (such as when transitioning from one railroad’s territory to 

another). In this way, the conductor serves to remind the locomotive engineer of important 

mode transitions. 

• Manually lines switches when moving in and out of a siding. This requires that the conductor 

get off the train, align the switch for the siding, wait for the train to pass, manually realign 

the switch for the mainline, and then walk to the front of the train. 

• Be responsible for the train consist. 

The conductor is responsible for checking to make sure that the engineer is aware of relevant 

information related to operating the train. If the conductor isn’t sure that the engineer is aware of 

something or is under control, he/she is expected to say something. The locomotive engineer 

can also catch and correct errors made by the conductor. An example was given where a train 

was in a yard. The conductor told the locomotive engineer that he had a “restricted proceed” 

signal, when in fact the train was supposed to stop. The locomotive engineer was more 

experienced and recognized that you don’t get restricted proceed signals in a yard. He 

questioned the conductor and discovered the error. 

3.2 Knowledge and Cognitive Functions involved in Operating a Train 

Figure 2 provides a model of some of the major cognitive functions and processes that underlie 

locomotive engineer performance when operating a train. It is adapted from a model of train 

engineer performance developed by McLeod, Walker, and Moray (2005). It contains the same 

basic high level cognitive functions depicted in Figure 1, with more detail provided on the 

specific knowledge and cognitive functions relevant to locomotive engineer performance. This 

model has been used as an organizing framework for synthesizing and presenting the results of 

the CTA with respect to cognitive functions involved in operating a train and the challenges that 

arise. 

The results of the CTA support this model of locomotive engineer performance. The results 

illustrate the knowledge and skill that allow locomotive engineers to operate trains safely and 

efficiently in today’s environment and point to ways new technologies, such as new train control 

technologies, can support performance as well as introduce new sources of cognitive demand. A 

high level summary is provided below of the elements of the model and how they combine to 

guide the performance of locomotive engineers. The sections that follow will provide more 

details with respect to some of the major cognitive elements and challenges that affect 

locomotive engineer performance. 

As depicted in Figure 2, operator knowledge and skills provide the foundation underlying 

operator performance. These include knowledge of the physical characteristics of the route (e.g., 

track grade; physical landmarks) and knowledge of train handling characteristics (e.g., 

characteristics of specific locomotives). They also include knowledge of the train schedules, 

operating rules and procedures, and informal practices based on organizational culture. In 

addition, they include skills and strategies developed through training and experience, such as 

 14
 

train handling strategies that are fine-tuned to the route and the particular train characteristics 

that have been built up from experience. 

This long-term knowledge combines with current information obtained from direct perception 

(e.g., displays inside the cab as well as the scene outside the cab) to produce a situation model of 

the current state of the world as it affects the current train handling activity (Figure 2). Key 

elements of the situation model include information about current time and location, physical 

surroundings (e.g., weather, track grade and conditions, milepost, landmarks, and signals) as 

well as information about other key agents in the environment that might impact safety (e.g., 

other trains in the vicinity, roadway workers, passengers, pedestrians, motor vehicles, and 

trespassers). It also includes information about factors that constrain or prescribe action (e.g., 

speed limits, signal aspects, and dispatcher directives). 

Knowledge and Skills

Current Situation Model

Route Knowledge Recent experience

Train handling strategies

Knowledge of rules and procedures

Current speed limit

Progress against timetable

Current location

Other trains in vicinity Roadway workers in vicinity

last signal aspect

Expectations Goals and Priorities

Train Handling

Strategy

Current speed

Monitor/Detect Communicate/ 

Act

Attention Allocation Plan/ Decide

Organizational culture

Knowledge of train (consist, locomotive, 

brakes, automated systems) Knowledge and Skills

Current Situation Model

Route Knowledge Recent experience

Train handling strategies

Knowledge of rules and procedures

Current speed limit

Progress against timetable

Current location

Other trains in vicinity Roadway workers in vicinity

last signal aspect

Expectations Goals and Priorities

Train Handling

Strategy

Current speed

Monitor/Detect Communicate/ 

Act

Attention Allocation Plan/ Decide

Organizational culture

Knowledge of train (consist, locomotive, 

brakes, automated systems)

Figure 2. Simplified model of the knowledge, and cognitive functions and processes that 

underlie locomotive engineer performance 

The situation model provides the basis for planning and deciding (Figure 2), which includes 

forming expectations, generating and prioritizing goals, deciding where to focus attention and 

planning what actions to take. For example, knowledge of the route, as well as the last signal 

aspect, can lead to expectation of upcoming speed restrictions or requirements to stop. 

Knowledge of roadway workers being in the vicinity might lead to expectations of roadway 

workers ahead. In turn, these expectations will influence attention allocation, action 

 15 
prioritization, and train control decisions (e.g., to focus attention outside the cab to look for 

roadway workers; to prepare to start braking action to slow down the train; or to prepare to blow 

the horn). The planning and decision making processes result in production of specific actions 

such as changes in train speed, application of brakes, blowing the horn, or communicating with 

others (e.g., a dispatcher and/or roadway foreman). In turn, the actions (and feedback) result in 

updates to the situation model as well as updates to the long-term knowledge and skills. 

The next sections provide more details with respect to some of the major cognitive functions and 

challenges that affect locomotive engineer performance. 

3.2.1 Developing and maintaining a situation model 

Developing and maintaining situation awareness represents one of the locomotive engineer’s 

core cognitive functions. The term situation awareness is formally defined as the perception of 

the elements within a volume of time and space, the comprehension of their meaning, and the 

projection of their status in the near future (Endsley, 1995). It emphasizes the ability of people 

to continuously extract environmental information, integrate this information with previous 

knowledge to form a coherent mental picture, which we refer to as a situation model, and use 

that situation model to further perception and anticipation of future events (Dominguez et al., 

1994; Endsley, 1995). 

In the context of operating a train, elements of situation awareness include awareness of: 

• Current location, which includes knowing exact location (e.g., within tenths of a mile) as 

well as where they are relative to territory boundaries (e.g., where they are relative to their 

movement authorities, and in which railroad territory they are), 

• Physical characteristics of the track that will impact train speed and braking requirements 

(e.g., track grade and physical condition of the track), 

• Fixed physical elements in the vicinity that support knowing where you are and influence 

running of the train (e.g., physical landmarks, mileposts, grade crossings, and stations), 

• Dynamically changing physical elements that impact running of the train and safety (e.g., 

location of temporary speed restrictions and location of work zones), 

• Location of trains and roadway workers in the vicinity, 

• Location of trespassers and potential hazards (e.g., children throwing stones), 

• Applicable speed restrictions and related restrictions (e.g., signal aspects and temporary 

speed restrictions), 

• Current speed relative to applicable speed restrictions, 

• Current position relative to schedule, 

• Transition points/mode transitions that signal changes in how the train should be operated, 

and 

• Characteristics of the locomotive and train consist (tonnage and length) that will impact train 

handling and braking. 

Jannsson, Olsson, and Erlandsson (2006) identified three distinct locomotive engineer train 

operating situations that involved different considerations in train handling. These were (1) out 

on the route, between two stations where the engineer is focused on the speed limits and on 

adjustment of the speed of the train; (2) approaching a station, where the engineer’s attention 

shifts to monitoring the surrounding environment for people on the platform, trains coming the 

 16
 

other way, signals, and braking decisions relative to position of the platform that come into play; 

and (3) leaving a station, where the engineer is focused on leaving the station as safely and 

quickly as possible to maintain schedule. 

Our CTA suggests that a broader number of distinct operating mode conditions and transitions 

are likely to be between operating modes that influence the set of considerations that impact train 

operation. These additional operating modes and transitions include: 

• Approaching a grade crossing, where a need exists, to monitor for pedestrians and road cars 

and to blow the whistle to alert them; 

• Approaching a work zone, where a need exists, to stop and obtain permission from the 

roadway worker in charge to enter; 

• Crossing a work zone, where a need exists, to monitor for presence of roadway workers or 

equipment on the track and to maintain awareness of limits of authority both with respect to 

location and time expiration; 

• Approaching an area where roadway workers are working on the side of the track, and a 

need exists to monitor for incursion onto the track and blow the whistle to alert them; 

• Transitioning between railroad territories that may signal a change in operating rules and/or 

a change in radio frequency for communication with the dispatchers, other trains, or roadway 

workers; and 

• Transitions in the methods of train operation, for example, in the case of new PTC 

technologies, train operation may differ when the PTC system is operating and when it is not 

operating. 

Knowledge of the current location is critical to locomotive engineer performance, because 

applicable speeds, authorities, and actions (e.g., braking, blowing whistle) depend on location. 

Locomotive engineers indicated that at all times they must know exactly where they are located 

to within a 10th of a mile. Complications include traveling at night and in inclement weather 

where visibility outside the cab is low. In addition, mileposts and other signage can be removed, 

defaced by vandals, or obscured (e.g., by foliage). 

With experience, locomotive engineers develop detailed knowledge of landmarks that provide 

rapid visual cues to location (e.g., familiar trees, houses, and bridges). A locomotive engineer 

said, “You’ll notice there is a certain house right before this interlocking or a golf course. You 

just see the territory so much that you equate certain landmarks with certain things that happen 

on the railroad.” 

Locomotive engineers also indicated that they get haptic cues of location (e.g., vibrations 

associated with portion of track and curves) as well as sight, sound, and even smell (e.g., near a 

farm). One locomotive engineer indicated that, “Even if you closed your eyes and you didn’t see 

the territory you could know by the sounds and feels where you are.” “Now that is another thing 

that experience brings—the feeling”, he said. “I’m going over the Mystic River Bridge because 

of that clack, clack, clack noise.” 

In addition to being aware of their own location, locomotive engineers actively engage in 

monitoring and communication strategies intended to develop and maintain situation awareness 

with respect to the location of other trains, roadway workers, trespassers, and other potential 

 17 
hazards in their vicinity. These active monitoring and communication strategies contribute to the 

overall safety and resilience of the railroad system. These strategies are described more fully in 

Sections 3.3.3 and 3.3.4. 

3.2.2 Generating Expectations and Thinking Ahead 

Experience allows locomotive engineers to build a mental picture of what to expect along the 

route. This enables them to anticipate what is upcoming and what actions will be required to 

guide, where to pay attention, and to rapidly focus attention on the unexpected and abnormal 

(e.g., a trespasser on the track). Being able to anticipate and plan ahead is particularly important 

in railroad operations where—because of the inertia of the train—locomotive engineers may 

have to initiate action early. 

Engineers explained that the majority of their attention is focused on anticipating what is likely 

to be up ahead and what actions it will require. A locomotive engineer stated, “What I’d be 

thinking about is not how fast I am going right now, or where I’m at right now, I’d be more 

interested in where I was going and what I had to be doing speedwise when I get to that point—

what is next.” 

Often the locomotive engineer will need to take action (start to brake or blow the whistle) in 

advance of (and in some cases in absence of) visual cues. One locomotive engineer mentioned 

that places, such at a curve, you can’t see a crossing, and in turn, the people at the crossing 

cannot see the train. In those situations, the engineer needs to know that the crossing is 

upcoming and to sound his whistle before going round the turn. Similarly, locomotive engineers 

need to maintain awareness of the length of the train and where the rear of the train is relative to 

key transition points. For example, they need to be aware of when the rear of the train clears a 

temporary speed restriction zone. 

Being able to anticipate what is likely to be up ahead and take preparatory action depends on 

developing an accurate situation model that combines information built from experience (e.g., 

long-term knowledge of the physical terrain including information on track grade) with 

information about current situational factors and constraints. This includes awareness of 

environmental factors (e.g., leaves on the rails making them more slippery or fog reducing 

visibility), location and activities of other entities in the vicinity (other trains, roadway workers, 

pedestrians), and situation specific restrictions (e.g., temporary speed restrictions and work zones 

that require permission from the roadway worker in charge before entering). 

Locomotive engineers constantly draw upon their mental model to project into the future and 

determine what actions to take. For example, in determining train speed, the engineer must not 

only consider current train speed restrictions, but speed restrictions that are in place ahead. 

Similarly, locomotive engineers draw upon their mental models to guide where to direct 

attention. One locomotive engineer explained it this way: 

 “I’m at milepost 56; my speedometer tells me I’m doing 90. I’m ‘allowed’ to get up to 125, 

let’s get to 125, now when do I have to get to below 125? That’s what I’m looking for next. 

Where’s my next station? Do I have any temporary speed restrictions? Is there anything 

between here and there on this track that I have to be worried about? I look at the bulletin 

order—is there anything in the bulletin order that tells me that there are guys working out 

here that I have to be prepared to look at for guys working on the track?” 

 18
 

Decisions that depend on projecting into the future include at what speed to travel, when to start 

to brake and how quickly, and when to sound the horn. In addition, the locomotive engineer 

may anticipate what track he or she will need to be on at the next station and what actions are 

required now to position themselves to move efficiently, without undue delays. One locomotive 

engineer provided the following example: 

“If I’m going to switch from one track to the other, let’s say there are four tracks, two inside 

tracks and two outside tracks. The inside tracks don’t make station tracks. If I’m on an 

inside track and I know I have to make a station stop up ahead, I want to make sure that I am 

going to get over to that track to make a station stop. If I don’t, I’m going to have to stop my 

train and tell them, ‘hey look, I’m going to have to make my station stop and I can’t do it 

from here, are you going to give me special permission to do it from here, or am I going to 

have to wait for you to line me up to make that stop?’” 

3.2.3 Monitoring and Detection 

One of the locomotive engineer’s primary responsibilities is to monitor activity outside the cab 

to detect and respond to unanticipated events. The engineers’ mental model allows them to 

anticipate what to expect along the route, it guides attention allocation and allows them to 

rapidly focus attention on the unexpected and abnormal (e.g., a trespasser on the track). 

The locomotive engineer’s primary monitoring channels are visual and auditory. The visual 

channel involves monitoring displays inside the cab as well as the environment on and around 

the tracks outside the cab. The auditory channel primarily involves monitoring and participating 

in communication over radio channels. 

3.2.3.1 Visual Monitoring 

The locomotive engineer has a number of displays to monitor inside the cab related to control of 

the train. These include, monitoring speed indicators, brake pipe and brake cylinder gauges, and 

amperage gauges. In addition, there may be in-cab signal displays that provide indication of the 

signal aspects that dictate train movement and speed. New advanced train control technologies, 

such as PTC technologies, have added additional in-cab monitoring demands. For example, PTC 

systems may include displays that indicate desired braking profile and target values (e.g., target 

speeds or braking distances) beyond which automatic train braking will occur. (See Section 5 

for more details). 

Although monitoring in-cab displays is important to ascertain train speed and control status, 

monitoring outside the cab is equally or more important. Engineers need to monitor for 

anticipated items such as changes in track grade, track signals, mileposts, signs, work zones 

markings, sidings, stations, and grade crossings. They also need to monitor for unanticipated 

objects. This includes signal aspects that are unexpected (e.g., that vary from the usual); 

signposts that are unexpected (e.g., a temporary speed restriction or work zone sign that had not 

been otherwise communicated); obstacles on the track such as animals, debris, discarded objects 

(e.g., refrigerators), individuals on or around the track (e.g., trespassers, roadway workers, 

people and vehicles at grade crossings), problems with the track (e.g., broken rails and 

misaligned switches), and other trains that are unanticipated (e.g., a train that is stopped on the 

track or coming in the opposite direction.). 

 19 
Being able to detect and recognize violations of expectations is one of the critical cognitive 

functions for safe train operation. However, often attention is driven by expectation, resulting in 

potential for error when unexpected conditions arise (e.g., failure to detect work zone sign, in the 

case where they had not been informed to expect a work zone). Consequently, as mentioned 

previously, locomotive engineers work hard to extract information allowing them to accurately 

anticipate upcoming events. For example, as described in the next section, they actively monitor 

the radio to anticipate the location, direction of movement and activities of trains and roadway 

workers in their vicinity. They also work actively to maintain awareness of the location of 

trespassers and obstacles on the track. 

3.2.3.2 Monitoring Radio Communication 

Locomotive engineers rely heavily on radio communication to extract relevant information to 

update their situation model, anticipate upcoming events, and plan ahead. They extract 

information from messages addressed explicitly to them, as well as messages addressed to others 

but relevant to the safe and efficient operation of their train. 

The locomotive engineers monitor the radio to extract information about the location and 

activities of roadway workers and other trains in the vicinity. A locomotive engineer explained: 

“Your listening skills improve. You listen to the radio even though they may not be talking 

to you. You may get a clue of what is going on by listening to the conversation on the radio. 

You know there is a workgroup up ahead, so you should be on the lookout for workers on the 

rail or maybe equipment on the rail. You want to turn your head light down. Start making 

noise with your whistle and horn to alert the people that you are coming.” 

Monitoring radio communication is valuable for building an accurate situation model of activity 

in the vicinity. It also provides a means of catching errors with potential safety consequences. 

One engineer provided an actual example that illustrates this point. He described a case where a 

dispatcher (erroneously) told a locomotive engineer that his track was protected, when in fact it 

was not. The locomotive engineer was able to catch the error by overhearing radio 

communication between the dispatcher and a second locomotive engineer. He overheard the 

dispatcher give the second locomotive engineer permission to cross the track. The (first) 

engineer immediately realized the dispatcher had made an error and was able to head off a 

potential collision by contacting the dispatcher over the radio. 

The results highlight the active strategies that train crews use to extract relevant information by 

“listening in” on radio communications directed at others. These active listening processes 

enable individuals in the distributed organization to identify information that has a bearing on 

achieving their own goals or maintaining their safety. Therefore, they can recognize situations 

where information in their possession is relevant to the performance or safety of others. Similar 

results have been observed for roadway workers and dispatchers. 

The results reinforce findings from other domains (e.g., space shuttle mission control, air traffic 

control, air craft carrier operations) regarding the importance of listening in on shared 

communication channels for supporting anticipation, contingency planning and catching and 

recovering from error (Luff, Heath, and Greatbach, 1992; Patterson, Watts-Perrotti and Woods, 

1999; Rochlin, La Porte, and Roberts, 1987; Smith, McCoy, and Orasanu, 2000). 

 20
 

In addition to actively monitoring radio communication to extract relevant information, 

locomotive engineers routinely engage in informal communication practices intended to enhance 

shared situation awareness among train crews, dispatchers and roadway workers and improve 

overall system safety. This is discussed more fully in Section 3.2.4.2. 

3.2.4 Communication 

Train crews communicate with dispatchers, other trains, and roadway workers over two-way 

radio. In many cases, formal operating rules prescribe the form and content of the information to 

be communicated. Observations and interviews revealed additional informal, proactive 

communication practices, which have emerged that serve to increase efficiency of railroad 

operations as well as enhance overall safety. 

3.2.4.1 Formal Communication Prescribed by Operating Rules 

Communication requirements depend on the signaling systems and operating rules in place. For 

example, under centralized traffic control, train movement is governed by signals, so no verbal 

communication with dispatchers is required as long as no system malfunctions occur. In dark 

territory, where no signals direct train movement, train movement authorities are provided 

through verbal communication between train crews and dispatchers over two-way radio. 

Communication between train crews and dispatchers also arise when problems occur with the 

signal system or new temporary speed restrictions arise that dispatchers need to communicate to 

the train crews. 

Formal operating rules dictate the form and content of the information exchanged during these 

transactions. For example, in dark territory, a train crews will call the dispatcher to request 

authority to enter a portion of track referred to as a block. The dispatcher will enter into a 

computerized database the mileposts designating the start and end of the portion of track being 

authorized for the authority. The dispatcher will then read the information off of the computer 

screen to the train crew, who are required to enter the information by hand onto a paper 

authorization form and then read the information back to the dispatcher. The dispatcher 

confirms that the information read back is correct, and only then is the authority to occupy and 

work on that portion of track put in place. 

Train crews are required to contact roadway workers to obtain authority to enter work zones. In 

those cases, the train crew is required to contact the employee in charge via radio to obtain 

approval to enter the work zone. As in the case of obtaining authorities from dispatchers, the 

train crew uses a formal communication protocol when obtaining authority to enter a work zone 

from the employee in charge. This protocol involves documenting and reading back the authority 

received. 

Federal radio rules prohibit the locomotive engineer, who is engaged in operating a train, to take 

directives over the radio. As a consequence, unless the train is stopped, radio communication is 

handled by the conductor. 

Communication is also required between the locomotive engineer and the conductor. Crew 

members are required to communicate signal aspects to each other. 

 21 
3.2.4.2 Informal Communication to Enhance Shared Situation Awareness 

In addition to formally prescribed communication, numerous informal, cooperative 

communication strategies will enhance situation awareness and improve safety by alerting each 

other (e.g., train crews, MOW crews, and dispatchers) of potential safety hazards. This informal 

communication helps train crews anticipate upcoming events and potential hazards so that they 

are in a better position to catch and prevent problems. The following are some examples of 

informal communication observed during interviews of locomotive engineers and conductors. 

Dispatchers will call trains to alert them to unusual conditions that vary from their regularly 

expected routine. In particular, a case was observed in the NEC where the dispatcher called a 

locomotive engineer to alert him that he was approaching an unexpected signal and should 

prepare to stop. This event occurred because a train was stopped ahead. The dispatcher did not 

need to call the locomotive engineer because the signal aspect should have been sufficient to 

direct the train to stop. However, the dispatcher provided this redundant cue to reduce the 

possibility of error. The redundant cue served an important safety function. By alerting the 

locomotive engineer to the upcoming signal aspect, the dispatcher reduced the possibility that the 

engineer would miss the signal (because the engineer was not expecting it). Further, by 

explaining the reason for the signal aspect, he avoided the possibility that the locomotive 

engineer would wonder whether the unexpected signal aspect was a false signal. The dispatcher 

referred to the communication as a “courtesy.” We found that dispatchers, train crews, and 

roadway workers routinely engage in informal communication for the sole purpose of enhancing 

each other’s situation awareness. They routinely call these communications courtesies, but they 

clearly play an important role in enhancing overall safety and resilience of the railroad system 

(Roth, Multer, and Raslear, 2006). 

Locomotive engineers actively engage in communication to improve awareness of the location 

and activities of other trains and roadway workers in their vicinity. They will routinely call other 

trains in the vicinity to find out where they are and to alert them to potential hazards, such as 

trespassers, kids throwing objects, and problems on the track. They will also call to inform each 

other of the location and activities of roadway workers in the vicinity. 

One locomotive engineer explained that he routinely wrote down what trains were in the 

vicinity, which trains he expected to pass, and where he expected to pass them. He explained 

that one reason he did this was in case he saw something that was important to communicate. As 

an example, if kids were on the track, then he would want to alert other trains in the vicinity. 

The engineers mentioned that it was the dispatcher’s job to inform them of the location of other 

trains, but that they actively sought that information through direct communication with the other 

trains as a redundant safety check. As one locomotive engineer explained, “I imagine that 

dispatchers get busy too and things happen and there might be something they get wrapped up in 

and they can’t communicate everything.” 

The results highlight the active cooperative processes that train crews, dispatchers, and roadway 

workers engage in that enhance shared situation awareness and the overall safety of railroad 

operations (Figure 3). The active work that locomotive engineers engage in to build and update 

a mental model of the location and activities of others in the vicinity is consistent with the 

behavior we have observed of individuals from other railroad crafts including dispatchers and 

roadway workers (Roth, Multer, and Raslear, 2006). Also consistent with observations in other 

 22
 

railroad crafts, including dispatchers and roadway workers, is the emergence of cooperative 

communication practices that go beyond the requirements of formal operating rules. These 

informal, proactive communication practices foster shared situation awareness, facilitate work 

and enhance on-track safety. Interestingly, these communication practices were frequently 

referred to as courtesies highlighting their optional nature and positive contribution. 

Building and Updating a Situation Model 

• Location – who is in the vicinity and 

where are they? 

• Activities – what are they doing? 

• Intentions – For how long? What will they 

do next? 

Informal Communication Practices 

• Proactively contribute to shared situation awareness 

• Provide redundancy checks to catch errors 

High Reliability Performance 

Figure 3. Framework showing how informal cooperative processes across distributed teams 

build on and contribute to shared situation models and how the two combined can foster 

higher reliability performance and increased safety 

The results build upon and extend the literature on teamwork and the role of shared situation 

awareness in facilitating work and enhancing safety. They reinforce the view that informal 

practices of domain practitioners can contribute substantively to system resilience and safety 

(Hollnagel et al., 2006). This view contrasts with the more traditional perspective that 

emphasizes humans as a source of error that can degrade an otherwise safe system. 

3.2.5 Planning and Decision making 

Much of the train crew’s behavior is governed by operating rules, train schedules, signals, and 

track authorities. These dictate train movement, including what track to operate, maximum 

speed, and when and where to stop. 

Primary locomotive engineer decisions associated with operating the train relate to (a) allocation 

of attention, (b) train handling strategies that relate to control of speed and braking, and (c) when 

and where to blow the whistle. 

These decisions depend on prioritizing and managing multiple goals related to operating 

efficiently while maintaining safety. 

3.2.5.1 Prioritizing and Managing Multiple Goals 

Cognitive performance is goal driven. Locomotive engineers must balance two primary goals: 

operate efficiently and operate safely. 

The engineer must be concerned about the safety of the crew, passengers, consist, as well as the 

safety of individuals in the vicinity of the train. These individuals include roadway workers that 

 23 
may be working on and around the track, passengers and pedestrians that may be walking by or 

crossing the track, and other vehicles (e.g., high rail cars on the track and road vehicles at grade 

crossings). 

Efficiency of operation is a second primary goal. This goal includes staying on schedule, and 

operating the train in a way that minimizes equipment wear (e.g., wear on the brakes) and fuel 

usage. In the case of passenger trains, it also includes considerations such as passenger comfort 

(e.g., by braking smoothly). Under some conditions, these multiple goals may conflict with each 

other, requiring the engineer to make decisions that balance the multiple goal constraints. 

3.2.5.2 Establishing Priorities/Managing Demands for Attention 

Often multiple competing demands occur for the attention of locomotive engineers. 

These include: 

• The need to monitor for and respond to events outside the cab. Events outside the cab 

that require attention include anticipated events such as an upcoming station, speed 

restrictions, work zones or grade crossings grade changes, signage, as well as 

unanticipated events such as trespassers or obstacles on or near the track; 

• The need to monitor and respond to displays and equipment inside the cab. This 

includes displays and controls for operating the train, in-cab signals, displays associated 

with PTC systems, the alerter, and alarms associated with equipment malfunctions; 

• The need to monitor and respond to communication over the radio; 

• The need to communicate with other train crew inside and outside the cab (e.g., 

conductor, assistant conductor); and 

• The need to keep track of and conform to information provided in track bulletins (listing 

temporary speed restrictions; location of work zones, flag locations, constructions sites, 

etc.). 

Engineers cite the importance of being able to rapidly prioritize among competing demands for 

attention, and overcoming distractions for safe operation. They indicated that managing 

attention demands is a difficult skill that requires experience to learn. 

Engineers indicated that their first priority was running the train and responding to events 

outside the cab. This takes priority over other things such as responding to radio 

communication. For example, if they were in a situation where they were getting ready to blow 

the horn (e.g., at a grade crossing, saw roadway workers in the vicinity) or were getting ready to 

change speed, then they may delay responding to the radio. 

Conversely, they indicated that if they were engaged in activity that drew their attention inside 

the cab, they might slow down the train to compensate. One example involved radio 

communication. Talking over the radio requires that engineers face the radio, therefore reducing 

the ability to monitor outside the cab. As a consequence, they might slow down the train a little 

to compensate. 

Another potential source of distraction is engine malfunction alerts. The engineers stressed the 

need to consider tradeoffs when deciding when and how to address a nonemergency engine 

problem. For instance, during a head-end ride an engine developed a problem. The engineer 

 24
 

stressed the importance of thinking through when and how to respond to the alert, so as to avoid 

unnecessary distraction from operating the train safely. He indicated that focusing on the engine 

problem could cause distraction and result in missing a speed restriction. He stressed that fixing 

the engine has lower priority relative to insuring that running a signal does not occur. “You 

don’t have the luxury of not being vigilant,” he commented, as lives are on the line. 

Managing multiple demands on attention and knowing how to prioritize among them was 

mentioned as one of the greatest challenges faced by inexperienced engineers. One relatively 

inexperienced engineer put it this way: 

“I think for me the most difficult thing that I would do, is I’m trying to brake or 

get the train down to speed for either a station stop or a speed restriction and I 

have the dispatcher trying to communicate to me. But what I will do is for me 

safety first, I’ll slow the train down, I’ll let the dispatcher sit and wait and get 

back to him when I feel I’m in a safe mode. Because there is so much going on 

out there sometimes and safety is your number one priority. I’ll just let him sit. 

And then, when I get on the radio with him, I’ll tell him why I couldn’t get back 

to him. I’m sure he understands. They don’t yell at you or anything.”

Another locomotive engineer mentioned a specific case where he was confronted with multiple 

competing demands for his attention. The example provides a clear illustration of the multiple 

simultaneous demands on attention that can arise and the need to rapidly work through the 

priorities among them to maintain safe operation. 

“I was brand new. I was still learning. I was pulling into a station. So, I was 

getting ready to stop. I was going over a grade crossing, so I was blowing the 

horn. Someone was calling me over the radio. It was a busy main street and there 

were people walking all around. When you have multitasking at that point, you 

have to think, ‘who is the priority here?’ . . . I had to worry about the road 

crossing first and foremost, because I don’t want to hurt anyone with the train. I 

have to also think that I will have to stop once I get over the road crossing. I want 

to pull the train clear of the road crossing and then stop. Then, I can answer the 

radio. But I wouldn’t go even near the radio until the other two things have been 

taken care of.” 

These examples provide clear indication that multiple simultaneous demands on attention 

represent one of the major cognitive challenges of operating a train. With experience, 

locomotive engineers develop the ability to rapidly prioritize among competing demands. 

The results point out the importance of carefully considering the impact of changes in 

technology on train crew attention demands. For example, some evidence that PTC technology 

may require locomotive engineers to focus more of their attention on in-cab displays reducing 

their ability to monitor activity outside the cab (See Section 4). More research is needed to 

determine whether this is the case and if the need to focus attention on the PTC displays 

decreases with the engineers’ experience. 

 25 
3.2.5.3 Train Handling Strategies 

Operating a train is an extremely complex task, requiring extensive knowledge of the rail line 

over which the train is running, and constant pre-planning of train speed and braking options 

several miles ahead (Booz, Allen, and Hamilton, 2006). With experience, locomotive engineers 

develop effective train handling strategies. Train handling strategies encompass decisions with 

respect to train acceleration and deceleration. The goals are to start and stop the train smoothly 

at the desired locations, and to control train speed so to stay within speed limits while 

maintaining on-time performance. 

One of the main challenges relates to developing train braking strategies (Booz et al., 2006). 

The main elements in braking decisions relate to: 

• Whether to brake in a given situation, 

• The type of brake application (e.g., dynamic, air brakes, and blended), 

• When to start braking, and 

• The force to apply (e.g., full service or emergency). 

One characteristic of train operations is that braking distances are generally long. It can take up 

to two miles for a coal train going at 40 mph to stop. Even at 20 mph, it can take at least half a 

mile. Passenger trains are lighter, but they travel at faster speeds, as a consequence their braking 

distances can be a mile or more. 

Because braking distances are long, locomotive engineers plan ahead and anticipate the next 

point at which they will need to stop or operate at a reduced speed. In most cases, they will need 

to begin to decelerate long before they reach that location. One of the strategies that locomotive 

engineers developed for determining where to start braking is to identify landmarks and mile 

posts as cues for where to start braking. 

Whereas landmarks provide a general guide as to where to start to brake, in fact, the specific 

location where braking needs to start and the force that needs to be applied will vary depending 

on a number of dynamically varying factors. These include: 

• Number of cars (a freight train can have up to 200 cars), 

• Total weight of the train consist, 

• Mixture and distribution of loaded and empty cars (especially in the case of freight trains), 

• Specific characteristics of the locomotive, 

• Grade and curvature of the track (it can be hard to start on a steep upgrade and hard to slow 

down on a steep downgrade), 

• Allowable train speed (e.g. speed restrictions), 

• Weather (snow or rain), and 

• Season (leaves on the track can make them slippery). 

. 

The conditions that affect braking are constantly changing; therefore, braking decisions need to 

take a variety of factors into account in deciding where to start to brake and how much force to 

apply. One engineer explained, 

 26
 

“If an engineer is at Mile Post 80, and he is required to reduce his speed at Mile Post 85, at 

Mile Post 80 he is already thinking about how he is going to put the brake on, where he is 

going to put it on, how much he is going to put it on. Let’s add to that, that it is snowing, so 

the rails are slick, so that changes how he is going to brake, what kind of speed. The next 

day, the leaves are falling on the rail, so it is an additional problem.” 

So every day, even though he is at the same milepost, the engineer is required to think differently 

about the same problem. 

One important input into braking decisions relates to characteristics of the particular locomotive 

and consist. Engineers may be assigned a different locomotive each day. As a consequence, 

testing out the characteristics of the brakes is important at the start of the run. In the case of 

passenger trains, a running brake test is required by the Federal law at the start of each run. The 

purpose is to determine how the train brakes are responding. This gives the engineer an idea of 

how that train is going to operate during the braking and acceleration process. The locomotive 

engineer processes that information to form expectations with respect to how the engine will 

respond to braking and acceleration. As one engineer stated, “He works that into his operational 

plan for moving that train.” 

In the next section, we discuss the considerations that enter into braking decisions under normal 

operations as well as in emergencies when a person or physical obstacle may appear on the track, 

or a misaligned switch may occur. 

Normal Operations 

Braking decisions in normal (nonemergency) operations involve a variety of considerations 

including a desire for a smooth ride, especially in the case of passenger trains where passenger 

comfort is an issue. 

Locomotive engineers on passenger trains are particularly conscious of the need to maintain 

customer comfort. For example, one engineer mentioned the importance of not going around 

curves at a high speed. He indicated that he was always looking back to check if the cars were 

rocking. 

Engineers on passenger trains described releasing the brake on the engine when coming into a 

station. This results in a smooth stop as well as a smooth ride when leaving the station. Other 

considerations in acceleration and braking decisions relate to a desire to maintain schedule, 

minimize wear on the brakes, and save fuel costs. For example, locomotive engineers explained 

that they had developed braking strategies intended to minimize the time required to complete a 

trip (consistent with staying within authorized speed limits). They set the brakes late to minimize 

unnecessary loss of speed. 

Locomotive engineers also talked about strategies for negotiating track portions with varying 

speed limits to minimize the need to constantly accelerate and brake, which would place wear on 

the brakes. For example, one passenger locomotive engineer mentioned that if many curves 

were in a portion of track that required speed reduction to 100 mph, then he might choose to 

maintain a constant speed of 100 mph rather than repeatedly accelerating and braking. 

Equally important are safety considerations, including minimizing the possibility for derailment. 

For example, freight train operators described braking strategies for stretching out a long heavy 

 27 
train, and insuring that cars did not bunch up, especially when going down steep grades. The 

concern was to avoid the possibility of derailment. 

Freight operations impose more of a challenge on acceleration and braking decisions because 

freight trains are longer and heavier than passenger trains. A major concern relates to hilly 

territory where braking prematurely can make it difficult to get up the hill. It could result in 

stopping at an inappropriate location (e.g., a grade crossing), or could result in loss of air brakes. 

Similarly, potential exists for derailment if brakes are not applied appropriately. 

Because freight trains can be a mile in length or more, lags occur between when the brakes are 

applied in the front of the train and when the cars further back begin to brake. As a consequence 

of when brakes are applied, cars in the back of the train will initially be running faster than cars 

in the front of the train. This results in train compression with cars in the middle being squeezed 

from both ends. Locomotive engineers need to anticipate the pulling and compressive forces 

within the train, particularly in hilly terrain to prevent derailments or breaking the train apart. 

Emergency Situations 

The focus of acceleration and braking strategies during normal operations is to maintain a 

smooth ride, keep to the schedule, conserve energy, minimize wear on equipment, and prevent 

the possibility of derailment. Another class of braking decisions arises in emergency situations 

where a physical obstacle or person may appear on the track or a misaligned switch or broken 

rail may occur. 

In emergency situations the objective of the locomotive engineer is to stop or at least slow down 

the train, while minimizing the risk of train derailment. The engineer’s actions will depend on 

the nature of the obstacle, the speed of the train, and the length and weight (and weight 

distribution) of the consist. 

Braking decisions can be complex requiring rapid consideration of multiple factors. Although 

“rules of thumb” such as “first slow down” are often useful, experienced locomotive engineers 

recognize that situations can arise that require exceptions to the rule. An illustration is the case 

of a heat kink in the track that has the potential to cause a derailment. A locomotive engineer 

explained that this situation can create a dilemma. If braking quickly, the retarding force on the 

track structure itself might increase the chance of a derailment by further weakening the track. If 

braking slowly, then the train will travel over the track at a faster speed, which might result in a 

derailment. A solution to this dilemma that experienced locomotive engineers have implemented 

is to brake heavily at first (before reaching the bad portion of track) and then relax on the brake 

as you get closer to the bad track. This example shows that braking decisions are complex and 

not subject to simple rule of thumb solutions. 

3.2.6 Knowledge and Memory Demands 

Operating a train requires extensive knowledge and skill that is developed through training and 

experience. Required long-term knowledge includes operating rules and route information. In 

addition, train specific information and route specific information must be remembered by the 

 28
 

engineer (e.g., temporary speed restrictions, work zones, and consist characteristics). These place 

additional memory demands on the engineer. 

3.2.6.1 Knowledge Demands 

Train crews must memorize the operating rules that apply to territory in which they are 

operating. Although core sets of operating rules that are common across railroads (e.g., 

Northeast Rules Advisory Committee or General Codes of Operating Rules) exist, typically each 

railroad will have their own rule books with special instructions that vary from railroad to 

railroad. Knowledge of the operating rules can be particularly challenging in cases of trains that 

operate across multiple territories that utilize different rule books. In those cases, the locomotive 

engineer is required to be qualified on the rule books for all the territories that they are passing 

through. For example, locomotive engineers that worked off of the spare board (e.g., engineers 

who operate in relief of other engineers) out of Albany, NY needed to be qualified on five 

separate rule books. 

In addition, locomotive engineers need to qualify on the physical characteristics of the route. 

With experience, locomotive engineers develop a detailed mental model of the territory they are 

working. Four to 5 months may be required for an engineer to develop the knowledge to be able 

to think ahead and operate smoothly on a territory. The mental model needs to be highly 

accurate with respect to the physical characteristics of the track and surrounding territory. This 

includes the location and characteristics of structures and landmarks such as switches, signals, 

signage, bridges, stations, buildings, and grade crossings as well as the operating rules that apply 

to those sections of track (e.g., speed restrictions). 

The knowledge and experience of a route that locomotive engineers develop over time supports 

anticipation and planning ahead (McLeod et al., 2005). Route knowledge allows the locomotive 

engineer to control the allocation of cognitive and perceptual resources based on expectations 

about what is upcoming. It enables locomotive engineers to detect and interpret cues in the 

environment more rapidly (McLeod et al., 2005). 

This detailed route knowledge is critical to enable locomotive engineers to operate under low 

visibility conditions. It also enables them to initiate action in anticipation of upcoming 

conditions, such as initiating braking in anticipation of an upcoming curve or speed restriction. 

3.2.6.2 Memory Demands 

In addition to long-term knowledge demands, dynamically changing conditions also influence 

train operations, which the locomotive engineer needs to keep in mind. These impose short term 

memory demands. Examples are temporary speed restrictions, locations of roadway workers and 

work zones, and location of grade crossing with broken gates where the train needs to stop and 

flag to alert cars and pedestrians. 

Temporary speed restrictions and work zones may be listed on train bulletins that are issued 

daily and reviewed before a run. In some cases, temporary speed restrictions may be issued after 

the train bulletin was printed, and in those cases, they will be transmitted verbally by the 

dispatcher over the radio. 

Although in some territories signs alerting train crews to temporary speed restrictions and work 

zones may be seen, they are not always present or visible. They may never have been placed, 

 29 
signs may have been removed through vandalism, or they may be obscured by vegetation. As a 

consequence, locomotive engineers cannot rely on these external cues exclusively. They must 

develop strategies to help them remember when and where significant upcoming events such as 

temporary speed restrictions are expected. 

One locomotive engineer said, “One of the hardest things of being an engineer are the things that 

you have to remember that are specific to this trip. Things like whether there are work crews out 

there. You can forget that. There is usually a sign but not always.” Locomotive engineers have 

developed a variety of recall strategies and external memory aids to help them remember 

significant events coming up. In addition, others within the distributed railroad system also 

provide proactive support to the locomotive engineers to help them remember. 

Some of the memory aiding strategies included placing the train bulletin in front of them (e.g., 

affixing it to the front dash of the engine) and writing in the list of temporary speed restrictions 

in the order in which they will come up so that they can anticipate them. They would then cross 

them off as they passed each one so to clearly identify the next one. An locomotive engineer 

said, “I will probably look at it between 3 and 4 times between stops to make sure I don’t miss 

something.” 

A related strategy involved highlighting the speed restrictions that applied to their route. An 

locomotive engineer explained: 

 “I’ll highlight stuff. The reason why you have to is that they will give you a sheet and it can 

have as many as six different tracks on the sheet and you have to pick out what you are going 

to do. And it is fairly small print, and in a dark cab, you are paying attention to the railroad, 

you are listening to the radio, you are doing what you are supposed to do, those highlighted 

portions would be much easier to come to.” 

An interesting variant of the highlighting strategy observed that was demonstrated by another 

locomotive engineer. He highlighted speed restrictions that definitely applied to his route with 

one color and those that could possibly apply (say if he was rerouted) with a different color. This 

strategy combines the need to focus attention on what is definitely coming up next, with the need 

to think ahead and be prepared to accommodate unplanned contingencies. 

Locomotive engineers used sticky notes (e.g., placed on windshield) as a reminder of speed 

limits at different mile posts or any unusual conditions such as a unique station stop.

Similar strategies of creating external memory aids to cope with memory demands are used by 

new locomotive engineers to keep track of critical information such as the train schedule, which 

more experienced engineers eventually memorize. Several locomotive engineers indicated that 

when they first started they used “cheat sheets” with scheduled stops, scheduled meet points, 

crossings, mileposts and permanent speed restriction as memory aids, but that they have since 

memorized the information and no longer needed the cheat sheets. 

An interesting variant was reported by one Amtrak passenger train locomotive engineer that 

mentioned that he created his own set of cards where he wrote down arrival and departure times 

for each stop. He explained: 

“That way I know if I’m on time, or I’m running fast, or I’m running slow. A lot of the trains 

have ‘fat time’ in them; they cushion it up, to keep their on-time schedule performance. But 

people get very impatient if they just sit. If you get into Providence and you have 8 minutes 

 30
 

to sit there, people start wondering is there something wrong, how come we are not moving. 

So I may slow down a train to accommodate the fatness in the station. So I’m only sitting at 

the station 2 minutes vs. eight.” 

This is an interesting strategy that not only illustrates the use of external memory aids, but also 

the variety of subtle factors that enter into train speed decisions. 

In addition to external memory aids, other members of the distributed railroad operations team 

serve to provide reminders of critical information. For example, one of the conductor’s explicit 

responsibilities is to remind locomotive engineers of upcoming speed restrictions. Dispatchers 

will also sometimes call to provide reminders of upcoming speed restrictions or unusual 

conditions. Dispatchers are not required to provide these reminders. They do them as informal 

courtesies that serve to enhance the overall efficiency and safety of railroad operations. 

 31 
4. Impact of New Train Control Technologies on Cognitive Demands 

and Operating Practice 

The interviews and observations conducted at sites where new train control technologies were 

being introduced revealed that these new technologies can impose additional cognitive demands 

on train crews. These new cognitive demands, in turn, can lead to changes in how locomotive 

engineers operate the train. Sources of new cognitive demands include constraints imposed by 

the PTC braking profile that require locomotive engineers to modify train handling strategies; 

increases in information and alerts provided by the in-cab displays that require locomotive 

engineers to focus more attention on in-cab displays versus looking out the window and 

requirements for extensive interaction with the PTC systems (e.g., to initialize it and to 

acknowledge messages and alerts) that impose new sources of workload. 

 In this section, we summarize some of the main potential impacts of PTC systems on the 

cognitive demands placed on locomotive engineers and their operational consequences. These 

results are abstracted from a more in-depth report on the human factors impacts of the 

introduction of PTC systems on railroad personnel (Wreathall et al., 2007). 

Two points should be noted with respect to the following results. First, the PTC systems are 

described and analyzed as they were implemented at the time that site visits and interviews 

occurred (See Table 1 for specific dates when site visits occurred). In some cases, the PTC 

systems have undergone substantial redesign since that time. Second, in evaluating the impact of 

PTC technology on locomotive engineer performance, we assumed no change in train crew 

configuration occurs. This was the stated operating philosophy at the time the study was 

conducted. The following analysis does not explicitly consider any additional sources of 

cognitive workload that may arise should there be a transition to single person operations. 

4.1 Impact on Train Handling Strategies 

A consistent finding across the systems examined (Communications-based Train Management 

(CBTM), advanced speed enforcement system (ASES), incremental train control system (ITCS), 

and Electronic Train Management System (ETMS) was that they used conservative braking 

profiles that required initiation of braking early to insure that train would slow down to the 

desired target speed under restrictive assumptions (e.g., heavy train or slippery track). This 

meant that under most conditions the PTC system required the train crew to initiate braking at an 

earlier point than they were normally accustomed. 

The train crews consistently reported that they needed to learn new train handling strategies to be 

able to stay within the PTC braking profile. The train crews indicated that the PTC systems 

required that they initiate braking earlier than they were accustomed. If the locomotive engineer 

initiated braking later than the PTC system braking profile required, the system presented a 

warning (typically, first a visual warning followed, some seconds later, by an audio warning). If 

the locomotive engineer did not reduce speed to meet the system braking profile, then the system 

made a penalty brake application that caused the train to stop. A penalty brake application is 

highly undesirable because it significantly delays train operations and triggers documentation 

requirements to explain why the penalty brake occurred. As a consequence, locomotive 

engineers, across the systems in trial operation, consistently reported altering their braking 

techniques to conform to the requirements of the PTC braking profile. 

 32
 

Some of the locomotive engineers explained that before the introduction of the new train control 

system, they had developed braking strategies intended to minimize the time required to 

complete a trip (consistent with staying within authorized speed limits). They set the brakes late 

to minimize unnecessary loss of speed. This braking strategy is no longer possible with the new 

PTC systems. 

With experience, locomotive engineers are able to develop effective strategies for staying within 

the braking curve of the PTC system while still operating as efficiently as possible. Locomotive 

engineers indicated that, as they gained experience with the PTC system, they learned to delay 

initiation of braking, coming as close to the point of initiating a penalty brake as possible, 

without actually exceeding that point to maintain efficient train operation. 

One locomotive engineer provided an example of a train crew strategy for maintaining operating 

efficiency while avoiding a penalty brake application. The new train control system in question, 

ITCS, includes target speed and time to penalty (TTP) for the upcoming speed restriction (See 

Figure 4). The TTP starts at 30 seconds (s). When the 30-second visual warning appears, the 

locomotive engineer has 30 s to reduce the locomotive’s speed to fall within the system specified 

braking curve to avoid penalty brake application. The 30-second count down continues until the 

locomotive engineer enters the braking curve. If the time-to-penalty brake value drops below 10 

s, the system gives an audio warning. When it gets to zero, a penalty brake is initiated. If the 

train speed goes below the braking profile target value before the countdown reaches zero then 

the countdown stops. The locomotive engineer explained that if you started to slow down as 

soon as the 30-second countdown appeared and stabilized the value at 27 s, you would be 3⁄4 of a 

mile back from the speed limit location when you slowed down. In contrast, if you stabilize it at 

1 to 2 s, you will be 500 ft from it, which is more reasonable2

. The locomotive engineer 

indicated that with experience, locomotive engineers tend to get closer to the edge of a penalty 

brake to increase train time efficiency. 

 

2 The specific braking values are a function of the length of train and type of braking used. In this case, the 

locomotive engineer was referring to 12 pound blended brake application. 

 33 
Mode Light 

Current Speed Limit 

30 MPH Target Speed 

Limit 

Target speed limit 

enforced in 3360 feet

Actual Speed 

18 Seconds Time To 

Penalty 

Target visible only if 

speed more restrictive 

Figure 4. ITCS In-Cab Display showing current speed and speed limit, next upcoming 

target speed limit, the distance to target, and a count down Time To Penalty (TTP) 

Locomotive engineers have also learned train handling strategies to avoid situations where the 

train control system might require them to stop unnecessarily. A case in point was provided by a 

second locomotive engineer running a train with a different train control system. The case 

involves approach signal updates. If the locomotive engineer comes to an approach signal, the 

system picks up that signal and requires the train to stop within 500 feet of the next signal—even 

if that next signal is green when the train reaches it (the system in question only sensed signals 

when it reached them; it had no indication of the reading of the signal ahead, and therefore was 

not able to update it’s control directive). This system behavior had the potential to cause 

significant delays, jeopardizing the ability to meet the train schedule. With experience, 

locomotive engineers developed strategies to avoid these situations. They simply slowed down 

ahead of an approach signal until the approach signal turns to clear to avoid a situation where 

 34
 

they enter an approach and have to stop at the next signal even if the signal is green. This is a 

clever strategy that, while resulting in some slowdown in train movement, is more efficient than 

having to come to a complete stop when it is unnecessary. 

The locomotive engineers pointed out that these strategies to avoid penalty brakes, while still 

maintaining train running time efficiency, require significant experience to develop. They 

stressed that someone who was new or on the extra board would not have developed these skills. 

As a consequence, they would be more prone to experience significant delays and/or initiation of 

penalty brakes. 

Interviews with locomotive engineers suggested it could take a month or more to learn where to 

initiate braking and adapt braking strategies appropriately. Similarly, extensive training and 

experience can be required to learn the variety of conditions that can arise causing the PTC to 

malfunction or initiate a penalty brake unnecessarily and how to avoid or deal with them. 

Locomotive engineers require sufficient training and experience to anticipate these situations and 

learn how to deal with them. 

4.2 Impact on Attention Allocation and Monitoring—Shifting Attention to In-Cab 

Displays Versus Out the Window 

Across the systems examined (CBTM, ASES, ITCS, ETMS), locomotive engineers reported a 

need to focus visual attention on the in-cab displays, at least initially, reducing their ability to 

look outside the window. Einhorn, et al. (2005) reported a similar finding. Locomotive 

engineers reported that they needed to carefully monitor the in-cab display to stay within the 

braking curve and avoid a penalty brake application while still operating at an efficient speed. 

The need to carefully monitor in-cab displays emerged as a particular concern in situations 

where there was little latitude for schedule deviation and the train needed to pass through 

territory with different speed restrictions. When the locomotive engineer approaches a block 

with a speed restriction, the locomotive engineer monitors the in-cab display carefully to stay 

close to the maximum possible speed, while avoiding a penalty brake. For example, in the ITCS 

system, engineers indicated that they carefully monitored the countdown to penalty brake 

readout so to avoid a penalty brake while not reducing speed prematurely (Figure 4). 

Locomotive engineers working with the ASES system reported using a similar strategy. In 

ASES, the engineers attempted to keep the current speed indicator (a black bar) close to the edge 

of (but still within) the green band that graphically displays the instantaneously changing 

maximum authorized speed that is calculated from the braking curve (Figure 5). As a 

consequence, when they get close to a speed restriction, the locomotive engineer focuses 

attention on the in-cab display and spends less time looking out the window. 

 35 
Figure 5. ASES In-Cab Display. The green band shows the maximum authorized speed, 

the black mark shows the current speed, and the yellow band shows the target speed being 

approached. 

Locomotive engineers indicated that the tendency to focus attention on the in-cab PTC display, 

which prevented them from looking out the window, gradually lessened with experience. For 

example, ITCS locomotive engineers indicated that, after about a month of operating with the 

system, they spent less time monitoring the in-cab display. However, several of the locomotive 

engineers reported that, even when locomotive engineers became experienced with the PTC 

system, they were still not able to look out the window as much as needed. 

The locomotive engineers expressed concern about situations where it is important to look out 

the window to avoid hitting roadway workers, pedestrians at highway-railroad grade crossings, 

or trespassers. For example, one locomotive engineer described traveling through a curve where 

people often trespass. He found himself focusing on the in-cab display to be sure he stayed 

within the braking curve instead of looking out the window. 

The locomotive engineers indicated that they needed to maintain their focus outside the window 

and be prepared to sound the horn in case they see a trespasser, motor vehicle driver, or roadway 

worker. They were concerned that with their focus on the in-cab display, they might miss 

unauthorized people on the right-of-way. This issue is a particular problem in territory where 

many grade crossings exist. 

4.3 Improved Anticipation 

In addition to providing predictive braking, some PTC systems include preview information that 

enables locomotive engineers to anticipate and prepare for track conditions some distance ahead 

of the train. Information may include upcoming speed restrictions (both permanent and 

 36
 

temporary speed restrictions), location and velocity of nearby traffic, and upcoming distance 

cues (e.g., mileposts, switches, and stations). Including this type of information in the PTC 

displays reduces memory demands on locomotive engineers (e.g., reduces the need to remember 

upcoming temporary speed restrictions), fosters a more accurate situation model, and makes it 

easier for locomotive engineers to generate expectations and prepare for upcoming conditions. 

 At the time we examined the PTC systems, CBTM, ASES, ITCS, ETMS and North American 

Joint Positive Train Control (NAJPTC) varied in the amount of preview information they 

provided. Comparisons will be examined of the information provided by the different PTC 

systems as they were implemented at the time site visits and interviews were conducted (See 

Table 1 for specific dates of site visits). 

The CBTM system is intended as an overlay system that only activates when an authority is 

predicted to be violated. This system does not provide preview information. ASES shows 

current speed, target speed at the upcoming speed restriction and instantaneous maximum 

authorized speed as calculated from the braking curve. 

ITCS displays current speed and target speed. ITCS also provides milepost information, giving 

the engineer train location. Of the systems examined, the NAJPTC system provided the most 

preview information. The display indicates the location, length, and current speed of the train. It 

also provides 6 mi of look-ahead of the track and depicts upcoming mileposts, track layout, hot 

boxes, sidings, and crossings. 

Whereas providing upcoming track information contributes to the need for locomotive engineers 

to focus attention on the in-cab displays, feedback from the locomotive engineers interviewed, as 

well as results of simulator studies, suggests that providing the engineers with preview 

information is helpful. The evidence (Einhorn, et al, 2005) suggests that preview information 

enables engineers to make better (i.e., safer and more efficient) decisions in the time available. 

Several simulator studies have demonstrated that displays incorporating preview information can 

increase safety and efficiency of train operation (Askey, 1995; Einhorn et al., 2005; Kuehn, 

1992). Kuehn (1992) showed that displays that incorporated gradient, authority, and speed 

restriction preview (5 mi ahead of the train) resulted in increased safety, as measured by the 

number of speed violations and red signal violations, as well as reduction in fuel consumption. 

Askey (1995) examined the effects of providing varying levels of preview information on 

locomotive engineer awareness, safety, and efficiency. The study found that as levels of 

information display increased, performance improved on a variety of measures, including 

station-stopping accuracy, schedule adherence, and reaction time to unexpected signal changes. 

Finally, Einhorn, et al.(2005) evaluated preview displays that provided upcoming speed 

restrictions, location and velocity of nearby traffic, and upcoming distance cues (e.g., mileposts, 

switches, and stations). The study manipulated the amount of look-ahead (1.5 to 3.4 mi and 

variable look-ahead). The results showed that preview displays improved performance on a 

number of train control tasks, including routine speed control, signal adherence, brake reaction 

time latency and schedule adherence. Performance was best for variable preview where the 

amount of look-ahead varied as a function of train speed. 

Interviews with locomotive engineers of PTC systems indicated that the engineers perceived 

preview information as valuable to improve safety and efficiency, independent of the predictive 

braking aspect of PTC. ITCS locomotive engineers felt that the display of milepost reinforced 

 37 
their mental model of the territory and provided important safety benefits in poor weather with 

limited visibility. Similarly, Amtrak staff interviewed regarding the NAJPTC system indicated 

that the NAJPTC display of the upcoming track and their location on the track would be very 

useful in helping them operate the train in cases where visibility was poor (e.g., in fog or at 

night). The preview information is expected to aid locomotive engineers in operating trains at 

higher speeds (e.g., above 79 mph) where there is less time available to process and respond to 

information outside the window. 

4.4 New Sources of Workload 

The PTC system creates new sources of workload and distraction. Sources of workload and 

distractions include the need to acknowledge frequent (and often non-informative) audio alerts 

generated by the PTC system and the need for extensive input to the PTC system during 

initialization and when error messages occur while operating the train. 

4.4.1 Audio Alerts as a Source of Workload and Distraction 

NAJPTC and ITCS locomotive engineers raised the issue of too many audio alerts and the need 

to acknowledge them as a potential workload problem. 

NAJPTC locomotive engineers mentioned a specific example that occurred during a set of test 

runs. The PTC system includes a train location determination system (LDS) that is able to locate 

train position within 10 ft. However, on a couple of occasions, the LDS system experienced 

difficulty identifying the train location. This difficulty triggered an LDS failure alarm. The 

alarm beeped repeatedly and required the locomotive engineer to press a button several times to 

acknowledge the alarm. The operational personnel expressed concern that this resulted in a 

heavy workload. It required two people to handle the situation. One person acknowledged the 

alarms while the other continued to operate the train. This was an early test of the system, and 

no consequences of failing to respond to the alert occurred. In an operational system failure to 

respond to an alert quickly might result in a penalty brake. 

ITCS locomotive engineers mentioned a similar concern with too many audio alerts that need to 

be acknowledged, creating unnecessary distraction and workload. One designer mentioned that, 

during the design process, he had removed some alerts based on recommendations of the 

locomotive engineers. He indicated that the system provided audio alerts to signal permission to 

resume speed, as well as upcoming speed restrictions. He suggested limiting alerts to warning of 

potential problems (e.g., an upcoming speed restriction that might be missed) and avoiding their 

use for positive situations (e.g., when a speed restriction is no longer in effect). 

The experiences of European railroads suggest that the concern expressed by the locomotive 

engineers regarding too many non-informative alerts has a potential for negative safety 

consequences. Operators may respond to poorly designed audio alerts automatically without 

fully processing their meaning, thus defeating their purpose (Pasquini, et al., 2004). This is 

consistent with an extensive body of human factors literature that indicates that individuals are 

likely to ignore alarms when a high false alarm rate exists (e.g., Getty et al., 1995). 

A recent analysis of signals passed at danger (SPAD) in Italian railways suggests that 

computerized systems intended to provide in-cab alerts of upcoming stop signals, if poorly 

designed, can fail to serve their intended alerting function (Pasquini, Rizzo, and Save, 2004). In 

the case examined by Pasquini, et al. (2004), a locomotive engineer missed a stop signal in spite 

 38
 

of an in-cab display system that provided an auditory warning of upcoming stop signals and 

required an explicit acknowledgement of the alert (via a button push). The analysis conducted 

by Pasquini showed that, because of the way the alert system was designed, it promoted a 

tendency to automatically press the acknowledgement button when the alert came on without 

actually processing the alert message. As a consequence, even though the locomotive engineer 

received and acknowledged an in-cab alert indicating an upcoming stop signal, he did not know 

he was approaching a stop signal. 

Analysis of the case reveals how poor alert system design can cause a system to lose its alerting 

function. One problem with the system was that the alerts were generally uninformative. The 

system attempted to predict the signal aspect for the next block and provide a warning, but in 

many cases the prediction was inaccurate. Typically, when a train entered a block (block n-1), 

the system would alert the locomotive engineer that the signal for the next block (block n) would 

be an approach signal. In most cases, the signal would turn to clear before the train reached the 

next block. As a consequence, experienced locomotive engineers perceived the system as a 

noisy distracter that must be silenced as soon as possible. Observation of train crews revealed 

that, as they approached a block, experienced locomotive engineers tended to look out the 

window with their fingers on the acknowledge button, ready to press it as soon as the auditory 

alert came on. They pressed the acknowledge button automatically without looking at the in-cab 

display that indicated whether the next signal was predicted to be approach or stop. Because the 

auditory sound was the same for stop and approach signal alerts, and the acknowledge button 

was the same in both cases, the locomotive engineers acknowledged the alert without processing 

whether the predicted signal aspect for the next block was a stop or approach. 

This example points to several important principles for design of effective alerting systems. 

Most importantly, the alerts must be accurate and informative. One of the most frequent 

problems with alerting systems is that they have a high false alarm rate, which causes users to 

ignore them (Getty et. al., 1995). Second, if an audio alert is used in an environment where the 

user needs to look somewhere other than the display screen (in this case locomotive engineers 

need to look out the window), then it is advantageous to use different audio signals to correspond 

to different alerting conditions (e.g., a different tone for approach versus stop). Third, if users 

must acknowledge an alert, they are less likely to respond automatically when different actions 

are required for different alert messages (e.g., a different button push for approach versus stop 

alerts). 

One of the negative consequences of alert systems with high false alarm rates is that users may 

disable them, particularly under heavy workload conditions. Data reported by Einhorn, et al. (in 

press) suggests that this is a legitimate concern with potential for negative safety consequences. 

The report discusses the problem of alarms as a source of workload and mentions comments 

made by the locomotive engineers participating in the study. One of the Amtrak engineers 

complained about the amount of electronic harassment in modern locomotive cabs. He related 

that many engineers cut out (turn off) the cab signaling and automatic train protection (ATP) in 

low-speed territory to remove the distraction of the warnings and focus their attention on very 

fine control of the train’s speed. However, the danger is that they forget to turn it on when they 

return to high-speed territory. 

 39 
4.4.2 Initialization/Interaction with PTC as a Source of Workload 

PTC systems generally require manually entered inputs at the start of a trip and after a shutdown 

of the system during train operations. The train crew must enter information that the system will 

use as parameters for safe operation. These data entry tasks provide another source of workload 

and distraction. In addition, manual entry errors can have safety implications. 

One example relates to initialization of the PTC system at the start of a train trip. The 

complexity of the information to be entered varies with PTC system. The NAJPTC system 

provides an example of a system that involves extensive input. At the start of a trip, the train 

crew must enter information about the train, its consist, and what track it is on into the PTC 

system. Although the data to be entered is straightforward, the data entry task creates additional 

workload. As a consequence, operating rules must take this additional workload into account. 

When the authors conducted the interviews with NAJPTC operational staff, the detailed 

operating rules and procedures were still to be developed. The authors raised the question of 

initializing the PTC system when the train was stopped or running. Amtrak personnel felt that, 

in the case of Amtrak trains where only one person is in the locomotive cab, the train would need 

to be stopped. 

Another example is the need to reinitialize the PTC system after it has initiated a penalty brake 

application. If the procedure is complex and time consuming, it may not be practical to follow. 

This issue arose in discussions with New Jersey Transit/ASES locomotive engineers. When a 

penalty brake application occurs, the locomotive engineers must cut out ASES and inform the 

dispatcher. They are then supposed to restart ASES. A procedure exists for cutting ASES back 

in, but the procedure is complex, difficult to follow, and time consuming. As a consequence, the 

locomotive engineers typically do not attempt to cut ASES back in. Instead, with the 

dispatcher’s permission, they run the train without ASES operating. They are able to do this 

because the system is still in trial use and not required to operate the train. Once the system 

becomes fully operational, running a train without ASES activated may no longer be an option. 

4.5 Potential for Complacency 

Another concern that has been raised regarding the introduction of PTC systems is that 

locomotive engineers will come to rely on the PTC system to alert them of upcoming speed and 

authority limits and to automatically stop the train should they fail to do so themselves. The 

concern is that, should the system fail, the locomotive engineers will not perform as well without 

it as they would have, if the system had never been installed. Complacency has been used as a 

label to refer to this problem (Sheridan, Gamst, and Harvey, 1999). It serves as an umbrella 

term that combines several concerns, including concern that the train crew may not recognize 

that the PTC system has failed (or is off) and is no longer providing the level of support they are 

expecting; concern that the train crew may be delayed in detecting and responding to PTC 

system failures; and concern that the crew may lose skill due to lack of practice, and thus may 

not be able to perform tasks as well when the system is not available as they would have, had 

they been performing the tasks all along without aid of automation. 

The term complacency comes out of the human factors literature; however, it is not a welldefined and universally accepted concept (Moray, 2000). This is partly because it has a 

pejorative connotation. Complacency seems to blame the person for unreasonably relying on 

automation and is closely related to the concepts of overreliance and excessive trust. One can 

 40
 

define complacency as relying on automation to a greater degree than is warranted by its 

objective level of performance. As has been pointed out by several prominent researchers, given 

the many things that people must attend to at any given time, if a system is known to be highly 

reliable, then it is reasonable that people should come to rely on it to function properly without 

needing to constantly check on its performance (Moray, 2000; Sheridan, 2002). A review of 

studies of trust in automation suggest that, rather than being overly complacent and trusting in 

automation, people tend to be less trusting of the automated system’s performance than is 

deserved by the actual reliability of the system (Moray, 2000). 

In context of railroad operations, complacency refers to the potential for people to become 

reliant on a job aid that is intended as a back up (like PTC), such that when it fails to work (or 

does not work as expected), the people are more likely to fail than if the job aid had never been 

installed. Review of actual incidents and comments by locomotive engineers during the 

interviews suggest that this is a legitimate concern. 

Complacency was identified as the most likely cause of one of the major rail accidents in the 

United Kingdom: the collision of a high-speed passenger train with a freight train on the 

approach to Paddington Station (London) at Southall in September 1997 (Uff, 2000). The 

following describes this incident and how complacency may have played a role. 

Example of Event: Southall

While approaching Paddington Station on September 19, 1997, a high-speed passenger train in 

service from Swansea passed through a sequence of three signals, each of which indicated a need 

to slow and stop before an interlocking. The signal system was set for an oncoming freight train 

to cross in front of the high-speed passenger train (Uff, 2000). The engineer did not slow the 

train at any of the signals and only appeared to react when he saw the freight train crossing in 

front of him at a distance when it was impossible to stop. The subsequent collision occurred at a 

closing speed of between 80 and 100 mph and resulted in seven passenger fatalities and 139 

injuries. The engineer of the high-speed passenger train survived with minimal injuries. 

The HST, like most other British trains, was equipped with an automatic warning system (AWS) 

that warned the engineer if he was passing any signal that was more restricting than clear by 

sounding a warning and displaying a visual indication. By acknowledging the AWS, the 

engineer can continue to pass the signals; no enforcement of the signals occurs if the warning is 

acknowledged (and is thus not a PTC equivalent system). However, on the day of the accident, 

the AWS failed (and was known to be failed) in the leading cab of the high-speed passenger train 

as it traveled to Paddington Station. 

The engineer operated the train appropriately up to the point of the accident, including obeying 

signals and speed limits. However, when interviewed immediately after the accident, the 

engineer recalled being preoccupied with getting his bag ready for arrival at Paddington 

Station—the terminus of the journey about 5 min from Southall. He received no warning from 

the failed AWS of passing the signals set to yellow and red as he approached the interlocking. 

The following passage is taken from the inquiry’s report: 

While drivers [engineers] accepted the traditional view that AWS was merely an “aid,” the 

reality was somewhat different, as the Southall accident has demonstrated. While it must be 

emphasized that the primary duty of a driver is to keep a vigilant lookout at all times, there 

 41 
must be a tendency for drivers, to an extent, to become dependent on the security of an 

automatic warning system on the approach to every signal. A full understanding of the 

effects of such systems depends on studies of human behavior in the particular environment 

of the driving cab, a subject that has so far received only limited attention. It can be 

concluded, however, that the absence of AWS was a contributory factor to the failure of 

Driver ------- to respond to signals SN280 or 270 at the crucial time (Uff, 2000). 

This accident, plus the SPAD accident at Ladbroke Grove involving a passenger train leaving 

Paddington Station in October 1999 (Cullen, 2000; HSE, 2000) led the United Kingdom rail 

authorities to consider the extension of train protection systems (TPS), the equivalent of PTC 

systems in the United States, to provide much more coverage in the United Kingdom (Uff and 

Cullen, 2001). 

Locomotive engineers interviewed at New Jersey Transit and ITCS felt that complacency was a 

legitimate concern. At New Jersey Transit they mentioned an anecdotal case where a 

complacency effect may have contributed to missing a signal in Cab Signal territory. In the case 

in question, the cab signal cut out. The locomotive engineer was aware that it had cut out. 

However, he was momentarily distracted (talking with a supervisor) and missed a signal. The 

locomotive engineers stressed that the individual it happened to was known as a very careful and 

conscientious locomotive engineer. This anecdote reinforces the point that complacency does 

not reflect a lack of conscientiousness but rather a tendency to come to rely over time on highly 

reliable and useful systems. 

4.6 Need for Awareness of Mode Transitions 

Another area of concern relates to changes in modes of operation. Locomotive engineers may 

have difficulty transitioning back and forth between train operation with PTC and train operation 

without PTC. FRA initiated a study that specifically looked at the potential challenges 

associated with mode transitions associated with PTC systems (Wreathall et al., 2007). Here we 

summarize some of our own findings related to PTC mode transitions as well as the findings of 

the Wreathall et al. (2007) study. 

Mode transitions fall into several types. One type of mode transition relates to operating a train 

that is equipped with PTC, but that depends on conditions and has the PTC system been active or 

not. PTC may not be operational on a PTC-equipped train because the train is outside of PTC 

territory or because the PTC system is malfunctioning. In the interviews, employees gave 

numerous examples of PTC-equipped trains that crossed in and out of territory where PTC 

coverage was available. For example, a freight train locomotive engineer operating an ITCSequipped train mentioned that when the train went off territory (e.g., in a yard), the ITCS 

coverage stopped. The system did not come back on until the train returned to the main line and 

passed a control point. The train can travel up to 2.5 miles on the main track before the system 

came on. These interviews also revealed numerous situations where the PTC system became 

inactive because of a malfunction. 

One concern with these kinds of mode transitions was that the locomotive engineer might fail to 

notice that the PTC system was inactive and no longer providing protection. Alternatively, the 

locomotive engineer may recognize that the PTC system was unavailable but fail to increase 

vigilance sufficiently to compensate for the lack of PTC protection. These concerns were similar 

to the concerns raised in the earlier section on complacency. The locomotive engineers will not 

 42
 

perform as well when the PTC is not activated as they would have had the system never been 

installed because they have come to rely on it. 

Interviews with locomotive engineers suggest that the possibility of failing to realize that the 

PTC system is no longer operational is likely to be low. Typically a prominent visual cue occurs 

indicating when the PTC system is operational. Locomotive engineers reported no trouble telling 

whether the PTC system was active or inactive. The question of whether locomotive engineers 

come to rely on the PTC system, and therefore perform less well when it is unavailable than they 

would have had it never been available is unclear. The earlier section on complacency addresses 

these issues. 

A second, related mode-transition issue arises in the case of locomotive engineers that operate on 

both PTC territory and non-PTC territory. Examples include locomotive engineers working on 

the extra-board that might be called to operate PTC-equipped trains on PTC territory, as well as 

non-PTC equipped trains on a different territory. The concern is how easily the locomotive 

engineer can switch between the two types of operation and whether any negative transfer occurs 

in going from operating PTC-equipped trains to non-PTC equipped trains and vice versa. 

Wreathall et al. (2007) analyzed the potential risk of human error associated with different types 

of PTC mode transitions. They concluded that when the PTC system is working normally, the 

dominant risk is the potential for human errors when the locomotive leaves the area covered by 

the PTC system. Contributors to errors that can arise in this case include: 

• Complacency, where the train crew has become overreliant on the protection provided by 

PTC and forget that coverage is no longer being provided; 

• Skill loss, where the train crew has lost some of the knowledge (speed limits, boundary 

limits, etc.) that is essential to safe handling of the train as a result of relying on the PTC 

system; and 

• Primary/backup reversal is where the crew comes to rely on the information provided by 

the PTC system (such as providing current location, indications of speed limits, etc.) and 

therefore has more difficulty operating trains that do not have this type of information 

available. 

Wreathall et al. (2007) indicated that risk of human error can also arise in cases where the PTC 

system malfunctions. They concluded that the primary concern in those cases relates to 

complacency following failures of the onboard equipment, where the crew, having isolated the 

system following its failure, forgets that coverage by the system is no longer available. 

Wreathall et al. (2007) concluded that compared with the existing accident rates without PTC 

operations, human errors arising from work mode transitions are likely to be much lower 

contributors to risk of accidents. Nevertheless they argued that railroads and PTC system 

designers need to be made aware that new accident types are possible, and measures can be 

taken in the design of PTC displays and in development of user training to prepare users to avoid 

the potential for work mode-related accidents. Section 5 of this report outlines some of the steps 

that can be taken to reduce the potential for error through improvements to user interface design 

and training. 

 43 
4.7 Impact on Teamwork Processes 

Another issue to consider is the impact of the PTC system on teamwork processes among 

members of the train crew including the locomotive engineer and the conductor. If the display is 

poorly designed, or poorly located, it can interfere with the ability of team members to serve as a 

mechanism to catch and recover from errors. For example, in cases where two people are in the 

cab (e.g., a locomotive engineer and a conductor) the second individual typically is charged with 

serving as a redundant check/reminder to the locomotive engineer running the train. This 

includes calling out signals as they are seen and providing reminders of upcoming speed 

restrictions. If the PTC display is placed in a location so that only the locomotive engineer can 

see the display, it reduces the ability of the second individual in the cab to provide a redundancy 

check. Pasquini, et al. (2004), reviewing an Italian cab signal system, reported that the location 

of the cab signal interface did not allow the second locomotive engineer in the cab to read off the 

alert messages, thus reducing his or her ability to detect when a locomotive engineer was about 

to violate a signal. A similar issue was raised during the interviews with locomotive engineers 

and conductors regarding the CBTM system. Several of the individuals interviewed argued that 

it would be helpful to place CBTM displays on the conductor’s side, as well as the side of the 

locomotive engineer so that the conductor could better support the locomotive engineer. 

 44
 

5. Implications for Introduction of New Train Control Technology 

Section 4 revealed that the introduction of new technologies, particularly PTC technology, has 

resulted in changes in the cognitive demands associated with operating a train. Some cognitive 

demands, such as the memory demands associated with keeping track of dynamically changing 

temporary speed restrictions, have been reduced. At the same time new demands have emerged 

such as the need to monitor in-cab PTC displays with the consequence that the ability to monitor 

outside the window for unanticipated situations have been reduced. Although PTC technology is 

likely to have a positive impact on overall risk of accidents, these new sources of cognitive 

demand can contribute to errors and accidents (Wreathall et al., 2007). Railroads and PTC 

system designers need to be made aware that measures can be taken in the design of PTC 

displays and in development of user training to improve train crew performance and reduce the 

potential for human error. Some of the steps that can be taken to improve PTC user interface 

design and train crew training are discussed. 

As noted in Section 4, the analysis provided in this report assumes no change in train crew 

configuration. This was the stated operating philosophy at the time the study was performed. 

Additional sources of cognitive workload may arise should there be a transition to single person 

operations that will need to be explicitly examined. 

5.1 Design Implications 

Current PTC displays vary widely in the amount of preview information they provide. More 

guidance is needed on the contribution of preview information on safety. Evidence from 

simulator research suggests that preview information may have a beneficial effect on safety 

independent of the predictive braking aspect of PTC. More research is needed to explore the 

relative risks and safety benefits associated with preview information displays (that may divert 

attention from out the window) and to develop guidelines for the design of displays that provide 

valuable preview information without excessively diverting attention from out the window. 

The fact that locomotive engineers will attempt to operate the trains to minimize running time 

while staying within the bounds of the PTC braking curve has implications for design of the incab displays. The in-cab displays currently provide limited cues with respect to when to initiate 

braking so as to stay within the braking curve. If the locomotive engineers initiate braking to 

avoid warning messages, they are likely to brake too soon leading to unnecessary time delays. A 

substantial learning curve exists to develop efficient braking strategies while avoiding a penalty 

brake application. In addition, the strategies that the locomotive engineers have developed 

require closely monitoring the in-cab display. A need exists for development of in-cab displays 

that make it easier to anticipate and stay within the braking curve without having to look closely 

at the in-cab display so that more attention can be allocated to looking outside the window. 

The locomotive engineers argued for the importance of being given the authority to suppress a 

penalty brake under conditions where it is inappropriate and potentially a safety hazard. It is 

important to put in place mechanisms to allow the locomotive engineer to override the 

automation and supporting operating rules that specify the conditions under which the engineer 

may do so. Situations will inevitably occur that are different than what the system designers 

anticipated and planned for. Providing some discretion to the locomotive engineer on the scene 

is important to deal with these unanticipated situations. 

 45 
A valuable area for research and development is improved in-cab displays that minimize the 

need to visually attend to the in-cab display to extract important information. Developing 

alternative display approaches would be desirable for indicating to the locomotive engineer 

where train speed is in relation to the desired deceleration rate without having to closely monitor 

the visual in-cab display. Options to explore include the use of nonvisual display modes, such as 

auditory or tactile displays (Sklar and Sarter, 1999). Heads-up displays that would allow the 

engineer to track critical operating parameters while still looking out the cab may provide an 

alternative promising research direction. 

5.2 Training Implications 

Introduction of PTC systems impose new training requirements for locomotive engineers. First, 

training is needed to understand how the PTC system works (technical theory). Second, training 

is needed to understand how to operate the PTC system under different conditions (e.g., how to 

initialize it, what the different PTC displays mean, what error modes might arise, and what to do 

in those different conditions) and the applicable operating rules (PTC operations). Third, handson experience is required to reduce the attentional demands associated with monitoring in-cab 

displays. Interviews with locomotive engineers suggest that a substantial learning curve exists to 

reach the point where the in-cab display does not serve as a source of distraction, diverting 

attention away from events out the window. Locomotive engineers must have sufficient 

experience in running a PTC-equipped train as part of training so that they get beyond the point 

where close monitoring of the in-cab display is required to avoid a penalty brake application. 

Fourth, hands-on experience and/or simulator training is required to learn the new train handling 

and braking strategies required to operate a PTC-equipped train to run efficiently while staying 

within the PTC braking profile (hands-on train handling). Finally, hands-on experience is 

needed to learn how to handle the traps, challenging situations, and failure conditions that are 

known to arise in special circumstances. 

Interviews with ITCS and ASES locomotive engineers indicated that current training typically 

involves a combination of classroom instruction on how the PTC system works followed by 

several trips with an experienced engineer. The interviews showed that the classroom training 

gave the engineers a solid foundation on how the equipment worked but that more hands-on 

experience was needed in running a PTC-equipped train. 

Several locomotive engineers indicated that one of the limitations of current training is that it 

does not provide sufficient opportunity to develop the new train handling and braking skills 

required to operate a PTC-equipped train. It also does not provide sufficient experience with 

non-routine situations (e.g., different malfunctions) and how to deal with them. One of the 

locomotive engineers suggested providing an opportunity for trainees to operate a PTC-equipped 

train in a more controlled environment (e.g., run a test train or a train simulator) where they 

would be able to practice train-handling skills without concern of the consequences of 

inadvertently initiating a penalty brake. Another advantage of running in a controlled 

environment, such as a test train, is that it would be possible to simulate different types of rare 

conditions that can arise so the trainee could learn what displays would come up (e.g., what error 

codes appear) and how to handle the situation. 

Examples of the kinds of special conditions that can arise and require specialized strategies 

include cases such as traveling on a steep uphill grade with a fully loaded train and coming upon 

 46
 

a PTC enforcement target location; and operating a PTC train with inaccurate consist 

information. 

Another issue raised with respect to training is the need to train crews to run the trains without 

the PTC system on, so that if the system ever fails, the engineer will still be able to operate the 

train safely. Locomotive engineers might become dependent on the PTC system to the point 

where they would not be able to run the train safely without it. 

It may be possible to selectively turn off some of the features of the PTC in-cab display to 

provide practice in running the train without them. For example, one of the lead engineers of the 

NAJPTC display suggested that some of the PTC interface features, such as the 6-mile track 

look-ahead display on the bottom of the screen, could be selectively turned off. Although the 

track look-ahead is likely to be a very useful feature for supporting situation awareness of the 

locomotive engineer, especially when outside visibility is low (e.g., in fog or at night), it may be 

useful to turn it off during some portion of training to insure that the train crews develop their 

own mental models of the track so that they are able to operate safely in cases where the PTC 

system is unavailable. Train crews may want to operate with the PTC system inactivated for 

selected trips during revenue service to maintain their territory knowledge as well. 

 47 
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