NTSB/RAB-08/03

E PLURIBUS UNUM

NATIONAL TRA SPORTATIO

N

B OARD

SAFE T Y

N

National Transportation Safety Board 

Washington, D.C. 20594 

Railroad Accident Brief

Accident No.: DCA-06-FR-007 

Location: Abington, Pennsylvania 

Date: July 1, 2006 

Time: 2:53 p.m., eastern daylight time1

Railroad: Southeastern Pennsylvania Transportation Authority 

Property Damage: $179,700 

Injuries: 38 

Fatalities: None 

Type of Accident: Collision 

Synopsis 

On Saturday, July 1, 2006, about 2:53 p.m., southbound Southeastern Pennsylvania 

Transportation Authority (SEPTA) passenger train 1143 collided head on with standing 

northbound SEPTA train 1134 near Abington, Pennsylvania. The southbound train was traveling 

about 11 mph when it struck the northbound train. As a result of the collision, the control cab car 

and two passenger cars on the southbound train and the control cab car on the northbound train 

were derailed. Thirty-eight passengers were injured and treated on scene. Of those, 29 were 

transported to local hospitals, and 8 were admitted. All six crewmembers from both trains were 

also taken to local hospitals; three of them were admitted. Total property damage was about 

$179,700. 

The Accident 

The accident2 occurred on single, straight track at milepost 2.8 on the Warminster Line, 

just south of a 3°15' curve. (See figure 1.) The weather was partly sunny, and the temperature 

was 83° F. At the time of the accident, both trains consisted of four electrically driven passenger 

cars, and each train had a lead car that was equipped with a control cab for the engineer. Each 

train had an engineer, a conductor, and an assistant conductor on board. 

 1

 All times in this brief are eastern daylight time. 

2

 The following sequence of events was determined from event recorder data, signal data, train dispatcher data, 

and postaccident testing and interviews. 
2 NTSB/RAB-08/03

 Figure 1. Map of a portion of the Warminster Line and the accident location. 

The dispatching plan called for the two trains to meet at the Grove South Control Point, 

about 1.4 miles north of the collision site, with the southbound train stopping on the main track 

at Grove South and the northbound train entering the siding at Grove South. The southbound 

train did not stop on the main track at Grove South, and it did not meet any train at Grove siding 

prior to the collision. The southbound train engineer did not comply with a total of three wayside 

signal indications—approach (yellow over red over red), stop (red), and stop and proceed

(red)—leading up to the collision. He also operated through and damaged the siding switch at 

Grove South, which was aligned for the northbound train to enter the siding. Yet, as the 

southbound train continued traveling between Grove South and the eventual accident site, the 

engineer passed three crossings and properly used the train horn at each, and he made two 

passenger station stops. When he saw the northbound train stopped on the track, he made an 

emergency brake application about 10 seconds before impact and warned passengers to brace 

themselves. 

A few minutes prior to the collision, the engineer of the northbound train passed a 

sequence of two signals—a clear (green) followed by a stop and proceed (red)—that concerned 

her. She was concerned because she had not received an approach (yellow) signal indication 

before the stop and proceed indication and she was operating the train on single track. The 

engineer stopped the train and tried calling the train dispatcher three times to confirm that the 
3 NTSB/RAB-08/03

signal instructions were correct. After receiving confirmation via radio, the engineer again began 

to operate the train and proceed in compliance with the signal instructions. When she saw the 

headlights of the southbound train, the engineer of the northbound train reapplied the brakes, 

stopped the train just prior to the collision, and told passengers to brace themselves. 

The train dispatcher acknowledged a system alarm for an overrun signal, via computer 

mouse click, shortly after the southbound train engineer operated through the siding switch at 

Grove South. However, he did not take any additional action in response to the alarm. The alarm 

sound and screen text type were not unique, and alarms were a common occurrence for routine 

matters during a dispatcher’s shift. Also, although he was responsible for only one 

desk/dispatching area, the dispatcher was covering two desks/dispatching areas at the time of the 

accident because his counterpart was taking a break. 

Investigation 

The investigation determined that the wayside signal system and equipment were 

functioning properly at the time of the accident. Weather conditions did not limit visibility. No 

impairing substances were found during the required Federal Railroad Administration 

postaccident toxicological tests of all crewmembers on both trains and the dispatcher on duty 

when the accident occurred. 

The engineer of the southbound train said that the train had operated normally. SEPTA 

records indicated that the cars of southbound train 1143 had been inspected and tested within the 

required intervals. The crew had performed an air test on the train before departing Warminster. 

The night before the accident the mechanical department completed an inspection of the 

equipment. No exceptions were noted. 

The engineer of the southbound train was qualified to perform his duties. He had passed a 

physical examination that included a vision test. He had been properly trained and tested, and 

SEPTA had determined him to be knowledgeable of and in compliance with its operating rules. 

He had begun working for SEPTA as an assistant conductor in October 2004, and he had 

transferred to the engineer training program in 2005. The accident trip was his fifth solo trip as 

an engineer. 

The train dispatcher was qualified to perform his job duties. He had passed SEPTA’s 

operational tests and the recertification examination for his position. He had worked as a tower 

operator for 13 years, which was a position with duties similar to those of a train dispatcher. He 

had been in the bus service as a driver for 7 months in 2004. In July 2004, he had transferred to 

the dispatching center, and he had been working as a train dispatcher for about 2 years when the 

accident occurred. 

The main track movements, including movements onto and off the main track and 

sidings, were governed by operating rules, a wayside traffic control signal system, and a SEPTA 

dispatcher at SEPTA’s control center located in downtown Philadelphia, Pennsylvania. 
4 NTSB/RAB-08/03

Southbound Train 1143 Engineer’s Actions 

The southbound train engineer’s descriptions of the signal aspects he had received at 

three locations prior to the collision did not match those recorded by the signal system or the 

results of postaccident testing. (See table 1 for a comparative summary of the accident signal 

data.) He misperceived and/or misinterpreted three different signal aspects, two of which were 

red, indicating the need for him to stop or stop and proceed. He also operated through and 

damaged the siding switch at Grove South, which had been lined for the northbound train. 

During the same accident trip, the engineer made appropriate station stops. He used the 

throttle and brakes correctly. He also used the train horn at crossings. Further, when he did see 

the northbound train stopped on the track and recognized the inevitability of impact, he made an 

emergency brake application and warned passengers. 

Table 1. Summary of accident signal data as described by the southbound train engineer and as 

collected by the National Transportation Safety Board.

Southbound Train 1143 

Engineer’s Testimony 

National Transportation Safety 

Board’s Collected Data 

Grove North Signal Approach Medium (yellow over 

green over red) 

Approach (yellow over red over red) 

Wayside signal equipment did not have 

a green lens in its middle signal unit 

Grove South Signal Approach (yellow over red over red) 

Saw three signal units 

30 mph speed restriction implied 

post signal 

Stop (red) 

Wayside signal only equipped with two 

signal units 

Was traveling 40 mph post signal 

Signal 506 Approach (yellow) Stop and Proceed (red) 

On the day of the accident, the engineer of the southbound train fulfilled most of his job 

duties. Wayside traffic control signals authorize train operations; complying with them ensures 

safe train operations. The engineer was aware of passenger station stops and crossings. He 

capably applied the brakes and used the train horn when appropriate, but he did not respond 

correctly to three separate signal aspects. The engineer was actively operating the train, but he 

was not adjusting the speed of the train or stopping the train as required by the wayside signal 

indications. 

Cab Signals 

All of SEPTA’s control cab cars, including those on the trains involved in this accident, 

were equipped with automatic cab signal and train control enforcement equipment that could 

display signal indications inside the cab and enforce them. However, on the Warminster Line, the 

wayside signal system was not capable of transmitting signal information to the cab signal 
5 NTSB/RAB-08/03

system installed in SEPTA’s control cab cars.3 Other lines of the SEPTA system had functional 

cab signals with automatic train control enforcement. On those lines, if an engineer failed to 

observe or misinterpreted a more restrictive signal (such as approach or stop) the cab signal 

system would alert the engineer, and if no action (such as a speed reduction) were taken, the air 

brakes would be activated. The engineer of the southbound train did not have such safety 

redundant technology backing up his actions. Without it, compliance with the wayside signals 

and the safe operation of the train rested solely on his attention and proper response to the 

wayside signal indications. 

Train Dispatching Alarm 

The alarm on the dispatcher’s computer system was used to alert the dispatcher to many 

abnormal system conditions; the overrun signal was only one of them. The alarm sound 

(monotonous and low) and the computer screen text appearance (small, red, and stacked along 

the lower half of the monitor) were the same for all exceptions; none were distinguished by 

significance. The train dispatcher was accustomed to receiving several non-critical alarms during 

a shift. As a result, in this accident, he reflexively cancelled the audible alarm for the overrun 

signal about 30 seconds after it sounded. Nearly 4 minutes and 20 seconds elapsed between the 

time when the alarm initially sounded and the collision occurred. Had the train dispatcher 

recognized the importance of the overrun signal alarm, he would have had time to call and warn 

the southbound train and the northbound train of the pending collision. 

Postaccident Actions 

Since the July 1, 2006, Abington accident, SEPTA has improved the safety of its wayside 

signal system. SEPTA is implementing a capital budget funding project systemwide. As part of 

the project, SEPTA is upgrading the Warminster Line with functional cab signals and automatic 

train control enforcement. The work on the Warminster Line began in January 2008, and SEPTA 

expects it to be completed by the end of 2009. 

SEPTA has also improved its train dispatching system since the Abington accident. The 

SEPTA train dispatching system was modified effective October 2007. Two features, “Signal 

Overrun” and “Catenary Power Loss,” were enhanced on all of the dispatching desk consoles, 

the chief dispatching console, and the Superintendent of Train Operations (STO) console. The 

change to the Signal Overrun feature is a critical one. If a train in the field overruns a signal, a 

voice will announce continuously, “signal overrun.” A pop-up message also will appear on both 

the dispatcher’s computer screen and the STO’s computer screen. Both the train dispatcher and 

the STO must acknowledge the message before it will turn off. With this system in place, it 

would require two individuals (the dispatcher and the dispatcher’s supervisor) to ignore the alarm 

before a collision similar to the one at Abington could occur. 

 3

 At the time of the accident, SEPTA was upgrading the signal system on the Lansdale Line to make the cab 

signals functional. In January 2008, SEPTA began upgrading the signal system on the Warminster Line. SEPTA 

expects cab signals on the Warminster Line to be functional by the end of 2009. 
6 NTSB/RAB-08/03

Probable Cause 

The National Transportation Safety Board determines that the probable cause of the 

July 1, 2006, collision of two Southeastern Pennsylvania Transportation Authority passenger 

trains near Abington, Pennsylvania, was the failure of the engineer on southbound train 1143 to 

comply with the wayside signals and stop the train on the main track at the Grove South Control 

Point. Contributing to the accident was the lack of a functioning cab signal system with 

automatic train control enforcement. Also contributing to the accident was a dispatcher computer 

alarm system that did not adequately alert the train dispatcher to the overrun signal. 

Adopted: June 17, 2008