In October 2006, I had the privilege of joining the ENO Foundation's International Transit Studies Program. Our mission was the study of "Rail Passenger Safety: Equipment and Technologies." I joined a team of 14 public transportation professionals as we toured Germany, France and the United Kingdom. The tour's agenda was comprehensive, and we met with government officials and transportation managers at German Railways Deutsche Bahn, French Railways SNCF, Paris Metro RATP, Transport of London, and engineers and designers at FAV Berlin/TSB, the Technical University of Berlin, Bombardier, Siemens Transportation, ALSTOM, DeltaRail Group and the British Rail Standards & Standards Board (RSSB).
During our study mission, our team learned a great deal from our European hosts about rail safety efforts that are being undertaken within the European Union (EU). Our team members were given the opportunity to ask frank and pointed questions about their undertakings, and to share our experiences about current efforts being undertaken within the United States to improve rail passenger safety. My particular focus during the trip was rail vehicle design characteristics. I learned a great deal about the overall efforts of EU transportation officials to enhance rail vehicle safety. Most importantly, during the trip I was given a firsthand look at actual design work and vehicle testing that is being conducted by rail car and locomotive manufacturers in Europe. In this article, I would like to make comparisons between the activities of our European colleagues and our similar efforts in the United States with regards to rail vehicle safety design enhancements.
Before I proceed with specifics regarding design issues, I would like to make an overall comparison of safety plans within the EU and the United States. In January 2006, the FRA implemented its National Rail Safety Action Plan in the United States. The highlights of this plan include reducing human factors accidents, operator fatigue, enhancing emergency response and the enhancement of rail car and locomotive designs, primarily the incorporation of crash energy management (CEM) designs into vehicles. The European focus upon safety is following a similar track. Within the EU, the European Railway Agency is overseeing the development of a truly integrated international railway system throughout the EU. As part of their common transport policy, members of the EU have adopted legislation that will guarantee standards of safety for the European railway system. Through this legislation, interoperability directives have been developed, which mandate a number of essential requirements to be met for interoperability. These include the elements of safety, reliability and availability of equipment, as well as the technical compatibility of rolling stock, their associated components and sub-components.
EU transportation officials stress that safety integration throughout Europe is critical. This is particularly the case regarding the design standards of railroad locomotives and coaches, heavy rail and light rail vehicles. They therefore established a philosophy that current safety standards from railroads in Germany, France, the U.K. and other European nations had to be, at the least, "maintained" at an acceptable standard level of safety during this change process. Through the efforts of all parties involved, overall safety standards will gradually improve as integration becomes a reality.
In the United States, the FRA's top priority is the prevention and reduction of accidents, particularly the reduction of human factors related accidents. In the event of an accident, FRA is looking to mitigate the consequences, specifically a prevention and reduction of injuries within rail cars. During the study mission, our team learned that EU officials have also developed programs that focus upon prevention and mitigation. EU engineers have categorized these critical safety variables into two components, "active safety" and "passive safety." They discussed the importance of both.
Active safety elements focus upon accident prevention or crash avoidance. An active safety element that is critical during the integrating process is the effective training of personnel who operate and maintain rolling stock. FRA officials with the United States are concerned with enhanced technical proficiencies of maintenance mechanics and technicians, as are our European counterparts. This becomes a critical issue, particularly with the incorporation of advanced technologies into various car systems, propulsion, braking, trucks and suspension systems, train control, etc. Managers in the United States and nations throughout Europe want locomotives and cars to operate safely, with all systems functioning as designed once they leave the maintenance facility. Therefore, efforts are being undertaken on both sides of the Atlantic to improve training.
Active Safety - Cab Design
Cab design architecture is a critical active safety element when considering crash avoidance. EU and U.S. transportation officials are concerned about driver fatigue and its adverse effect upon safe train operation. This includes the effects of repetitive hand and foot motions, right-of-way visibility, eye strain and body posture. EU cab designers have studied the eye, hand and foot movements of locomotive drivers and have developed a control panel and seat arrangement that is ergonomically superior to past configurations. Within the EU, a new ergonomically designed modularized cab is being developed to comply with future safety standards. Simulator and real-life testing of this cab are being conducted to ensure that a highly functional, practical design incorporates safety and comfort. This includes the shape and design of cab interior operational elements, the functional grouping of controls, digital train controls that provide greater responsiveness during acceleration and braking modes, one-hand train operation, improved night visibility, seat height adjustments and new cab display technology.
Engineers in the United States have also looked at improved cab designs that reduce fatigue and protect the crew. These can be seen in the monocoque cab design that has been incorporated into new freight and passenger locomotives.
Passive safety is the safety system that works with no human intervention to mitigate the consequences of an accident, including injury and death.
Vehicle designs play a paramount role in the protection of the drivers of rail vehicles as well as passengers in the event of an accident. EU transportation specialists and rail vehicle engineers are working to include advanced occupant protection characteristics into the designs of locomotives and rail cars. These include the construction of rail vehicle driver cabs, passenger compartments, seats, tables, wind and other interior partitions, grab handles and poles, windows, doors — entrance and exit areas, and inter-car vestibules. Two primary variables being considered for the design of safer vehicles are crash energy management (CEM) and the utilization of biomechanics in the design of safer vehicle interiors. Similar activities are being undertaken within the United States.
Passive Safety — Crash Energy Management (CEM)
In the event that all active safety variables fail and there is a head-on collision between two trains, passive safety devices must be designed into rail vehicles to mitigate injuries to the train crew and passengers. EU rail car designers are presently working to incorporate CEM characteristics into present vehicles that are being rehabilitated and new future designs. At the testing facility in Pueblo, Colo., tests have also been conducted utilizing trains in actual crash scenarios. Utilizing data compiled in these tests, U.S. engineers are working to design safer rail vehicles. A primary example of incorporation of CEM into cab car and coach designs is the 87 rail car contract for Southern California's Metrolink System.
CEM is a design concept that absorbs energy that is generated when a rail vehicle or a train consisting of several rail vehicles comes into frontal impact with another object. This design considers the longitudinal dynamics of the train, distributing collision energy among cars in a train consist. CEM rail cars can more efficiently absorb collision energy, as this energy is transferred to the front end of the locomotive, and to the following cars within the train. Key to the CEM design is the incorporation of a series of crushable elements into locomotive and car designs. In the event of a collision between a train of rail cars and another train or object on the right-of-way, the resulting vertical and lateral motions of the vehicles in the train are limited. Thus, coupled car interactions are controlled, and the saw tooth buckling and consequent overriding and derailment of the cars in the train can be successfully minimized. Most importantly, CEM maintains the occupant survival space and structural integrity of the locomotive and cars in the train. This reduces serious injuries and fatalities.
EU rail car designers have considered several scenarios during crash tests. These are also variables that are important within the United States parameters of weight and speed that were developed for each:
- Front end impact between identical trains.
- Front end impact between a streamlined passenger locomotive or rail car and a freight car with side buffers.
- Impact with a truck on a railroad crossing.
- Impact with a low obstacle on the right-of-way or a small auto on a crossing.
Passive Safety — Locomotive Cab Design
In the locomotive or operating cab car, the primary concern is the protection of the driver. In the event of a collision, the driver must be able to survive the initial impact, and have a means of escape. EU vehicle designers have been working on a monocoque cab construction design that will absorb the major stresses created as the result of the impact of a head-on crash.
The cab is designed with the driver's seat mounted on a platform. This platform moves under the extreme forces that are exerted in a collision. The seat is resultantly pushed away from the front of the locomotive toward the rear of the cab.
Special consideration has been given to doorways on the car body structure of the locomotive that lead to the engine room. These doorways provide a means of emergency egress for the driver, and have been re-enforced to ensure that frames do not buckle in the event of a collision. Doors can then be quickly and easily opened for escape. Designers are concerned about the opening motion of the doors, and have considered doors that can be opened in either the inward or outward positions. This will enable the driver to either pull or push the doors open quickly. This is a concern for designers, for the driver may either need to push or pull the door open. As an example, analysis indicated that the forces exerted upon the driver and door of a quickly braking train will make it virtually impossible for a driver to push a door against the direction of deceleration. The deceleration will make it easier to pull the door open. Also, there is a concern that damaged components in the engine room may make it impossible to push the door open. Pulling may provide the only alternative for a means of escape.
As noted earlier, the CEM designs are being tested for future construction of locomotives and passenger rail cars in both the EU and United States because it limits the deceleration rate, reduces the risk of derailment, reduces the risk of overriding (particularly on the front end of the locomotive) and maintains the integrity of each vehicle's car body structure, thus maintaining the survival space of the driver, other crew members and passengers.
Passive Safety — "Safe Train" and "Safe Interiors"
"Safe train" and "safe interiors" are projects through which EU vehicle designers have been working to enhance the interiors of passenger rail vehicles. Work is being conducted with the following objectives in mind:
- The preservation of survival space.
- The prevention of the intrusion of foreign objects from entering the passenger compartment, either from the under car section, the roof or the windows.
- Prevention of ejection of passengers through the windows or doors.
- Fire prevention. In the event of fire, inhibiting its spread throughout the compartment.
- Prevention and mitigation of passenger injuries while seated and standing.
- Escape aids in the event that passengers must evacuate for their safety.
Engineers within the United States have also looked at these variables, and have incorporated safer interior designs into the new Metrolink bi-level commuter cars.
EU engineers have been determining and recommending relevant criteria and design requirements for passenger accommodations in order to achieve the maximum vehicle crashworthiness and improvement in passenger safety. The study of past railway accidents revealed that secondary impacts within a rail vehicle seldom result in fatalities. However, passengers have received major injuries while seated or in a standing position during a collision. Studies have revealed that the speed of vehicles and their interior components reduces rapidly after a collision. However, the velocity of a projected occupant remains relatively constant. They will impact a table or the back of another seat while seated, or a pole, wind screen, stanchion or other object within the car before coming to rest. Engineers have utilized the science of biomechanics to study specific injuries that are sustained to the body when subjected to a collision with an obstacle within a rail car. Through actual tests conducted on crash dummies, 18 body segments have been studied: head, two arms, two forearms, two hands, two thighs, two feet and the vertebral column including five segments. Computer simulations have been developed through which dummies wired with sensors have simulated human injuries when subjected to collisions with objects within a rail vehicle.
Passive Safety — Seats and Table Designs
As noted earlier, EU rail officials and the FRA are concerned that occupant impact with seats represents the main cause of secondary impact injuries. Seats, however, also provide the most efficient way to restrict the bodily movement, and therefore minimize the seriousness of any inflicted injuries. Concerning the arrangement of seats, it has been determined that:
- Unidirectional seating is best for injury mitigation.
- The second best arrangement is an open bay with table. However, the table must possess thick round edges that have crush zones embedded into the table structure. The table must be firmly attached to the floor of the vehicle to prevent it from becoming a projectile.
- The third safest is an open bay without a table.
EU engineers have determined that the design of seats must satisfy several requirements. New seating designs will incorporate the following criteria. Engineers within the United States are also looking at these while looking to design safer seats.
- Resisting the impact forces occurring on collision.
- Possessing a seat back sufficiently high and well padded on both the front and back sides so as to afford proper support for the head and neck of a rearward traveling passenger, and not to cause face or neck injuries to a forward traveling passenger who impacts with the seat ahead.
- On a unidirectional seat equipped with a folding snack table, the table should be designed as to not constitute an injury hazard. Tables that automatically lift or fold in an accordion manner are being studied.
- The low back side of a unidirectional seat should also be equipped with an energy-absorbing padding element for the protection of knees and lower legs of the passenger in the seat behind.
- Finally, seats must be firmly mounted to the vehicle floor to prevent dislodging during the initial collision and secondary impact of passengers striking the seat.
- Seat belts were considered. However, it has been determined that they do not provide the utmost in desired protection. This deduction was made taking into account that all passengers would not wear seatbelts. In a unidirectional arrangement, passengers not wearing seatbelts would become projectiles that would collide with the seat ahead of them. If occupants in the forward seat were wearing the seatbelts, they would be thrown forward with the compounded weight of the non-seat belted passengers who were projected forward from behind. Studies are still being conducted concerning this and other seat considerations.
Utilizing Lessons Learned From Past Events
EU transportation officials and FRA officials have both looked at past events and are considering critical aspects of safer interior designs that will enhance emergency exiting of passengers. EU engineers presented detailed scenarios of past accidents with our Eno study team. They discussed lessons that were learned through their investigations of the accidents, including examinations of damaged rail cars and interviews that were conducted with surviving passengers. The engineers directly associated what they learned through their investigations with programs that have been implemented to design safer interiors.
Members of our team also discussed incidents that occurred in the United States which directly brought about changes in rail car safety. Two incidents specifically discussed were the collision of a Southern California Metrolink commuter train with an SUV that had been deliberately parked upon the right-of-way, and the head-on collision of a MARC commuter train with the Amtrak Capitol Limited in Maryland. Both incidents involved cab car collisions, the first with an auto, and the second with a locomotive. Fire, and the inability of trapped passengers to escape from the burning cab car coach of the MARC train were given particular attention.
Seats and Tables, Interior Appurtenances — Fire, Smoke Retardation
EU engineers are looking into seat, tables and other interior equipment materials that have a lower tendency to spread flame, with lower smoke toxicity. This is a special concern as they look for additional padding on seats and other interior equipment. Within the United States, strict NFPA fire standards have already been incorporated into the designs of rail vehicles.
EU engineers have studied past accident scenarios and have analyzed the effect of windows upon passenger fatalities and serious injury. Considering the results of the studies, they have had two primary concerns:
- Prevention of passenger ejection when windows break.
- Prevention of foreign debris from entering the passenger compartment when cars leave the right-of-way, saw tooth buckle and turn over.
In the event of an emergency, the EU designers have determined that it is best for passengers to remain within the confines of a vehicle until first responders arrive. This is the case if the car structures are sound and there is no fire or smoke.
Therefore they have determined:
- Hard glass windows must be impervious to hard projectiles that may be thrown against them during a collision/derailment.
- The windows must contain passengers. They must be persuaded not to exit through windows. Doors must be used for exit when available.
- Windows must provide egress as a last resort, and must enable entry by first responders.
The Eno team noted that within the United States, a different approach has been taken concerning window designs on long-distance and commuter rail cars. Several windows within each rail car must serve as passenger emergency escape routes. Handles are placed on these window frames, and can be utilized to remove the window molding so that windows can be removed. These handles must be present on both the interior of the cars for passenger access, and on exteriors for access by first responders. Escape windows must be clearly marked.
Doors are important on a rail vehicle because they provide a means of egress in the event of an emergency. As noted earlier, EU engineers are concentrating on strengthening the integrity of the car structure around door areas to ensure that they are not deformed in the event of a crash. Any deformations in the side and end door operating areas could inhibit the sliding action of the doors.
New designs include clear signage of luminescent materials that direct passengers how to operate doors in the event of an emergency where the electrical power is lost. On new cars, special emergency handles are being placed alongside doors with clear instructions for use. There are also buttons for direct communication with the train's crewmembers.
These ideas are also being incorporated into the designs of commuter rail, heavy rail and light rail transit in the United States.
EU engineers have given considerable attention to new emergency lighting technology. Studies of past accidents have determined that emergency lighting is essential to calm the fears of passengers who have been involved in the traumatic experience of a wreck. Passengers will be reassured by a well-illuminated car interior, and will have less of a tendency to panic. It is preferred that passengers remain aboard vehicles and await first responders. An illuminated interior will provide a greater sense of safety than one that is totally dark. Illumination may persuade passengers to remain aboard for assistance. Well-placed emergency lighting fixtures must also direct passengers to available exits when evacuation is essential.
Illumination will also help to reduce additional injuries to passengers as they negotiate vehicle interiors that may be clogged with debris and damaged structural areas. They determined that emergency lighting must be reliable, and have the following characteristics:
- Robust. Fixtures must survive all forces exhibited in a crash.
- Self-contained energy source.
- Must provide uniformity of lighting — no bright and shaded areas.
- Very low voltage, amperage draw.
- Emergency light must last a minimum of three hours.
Researchers investigated the utilization of light emitting diode (LED) technology for a new generation of emergency lighting. LEDs are low voltage, low amperage lights that are capable of emitting a bright light over an extended period of time.
Technological advances have produced a new spectrum of white light that can be clearly seen. Fixture lenses disburse light uniformly over a wide area. Because of their low current draw LEDs will remain illuminated for long periods of time on battery-generated power. Fixtures can be manufactured utilizing hard plastic which makes them robust against external forces. Because of these attributes, designers have determined that self-contained LED fixtures are ideal for emergency lighting in EU rail vehicles. LED units can be installed in the interiors of new cars. Because of their self-contained power supply, the fixtures can also be installed in older cars without the expense, man-hours and maintenance entailed with wiring installations.
The incorporation of LED technology into cars in the United States is being considered.
EU engineers have also looked at chemical technology and the development of luminescent striping and signage to assist passengers in rail vehicles in the event that electrical emergency lighting totally fails and the interior is left in darkness. Strips can provide a low level of lighting in the passenger compartment, and guide passengers toward emergency exits. Luminescent signs can provide critical information concerning vehicle exiting, the activation of emergency doors and other emergency apparatus. This technology is presently being installed in new railroad and metro vehicles throughout the EU.
Members of the Eno study team discussed the implementation of luminescent technology into Amtrak and commuter rail rolling stock in the United States. It was noted that the MARC train collision was a catalyst within the U.S. rail industry in this regard. The lessons learned during this event included the critical importance of passengers to have access to window and door safety exits, and the importance of outfitting cars with illuminated signs and strips that effectively direct passengers to these exits. Luminescent signs and strips must be visible for an extended period of time in a dark atmosphere where vision may be inhibited by dust and smoke.
Paul J. Messina is superintendent of Rail Investigations, Office of System Safety, MTA New York City Transit, and chair of the APTA Rolling Stock Equipment Technical Forum.