June 25, 2009

How do MetroLink trains stop safely?

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As you may have heard, on Monday night two D.C. area subway trains collided during rush hour. The accident occurred when one vehicle struck another vehicle, which was stopped on the tracks waiting for the passenger platform to clear at the next station. Sadly, nine people were killed, including the train’s operator, and over 70 people were treated for injuries. Investigation into the cause of the crash is ongoing.

Whenever an accident like this occurs, it naturally makes people wonder about the safety of their own local transit system. We asked Training Specialist Suzanne Whitehead to explain some of the safety precautions in place on the MetroLink system that work to prevent this kind of accident. One safety measure is the cab signaling system, which  Suzanne explained to me:

MetroLink uses cab signaling to determine the appropriate speed at which a train can travel based on the curve of the track, elevation, etc. The cab signal is sent through the rails to the train which is picked up by an antennae on the train. The Train Operator receives a cab speed on their dashboard so they know what speed to travel between 5 MPH and 55 MPH. When the trains travel at the designated cab speed, all the trains stay on schedule and stay separated from each other. If a train goes over the cab speed for a section of track the operator receives an audible alarm reminding them to slow down, if the train continues at the overspeed, a penalty stop will occur automatically. A penalty stop is a safety precaution built into the train system to stop the train from going at excessive speeds.

Another feature designed to prevent collisions is a system that prevents more than one train from being in the same stretch of tracks at a time. This is called a positive train control system. Suzanne says:

This system divides track sections into blocks. Each block can only accommodate one train at a time.  The logic built into the MetroLink system prevents trains from running into each other. When a MetroLink train is stopped in a block and the following train reaches that block’s limits, the system’s logic gives the MetroLink operator in the following train a Zero Cab Speed Signal. This zero cab signal stops the train. The MetroLink Operator contacts the Operations Control Center (OCC) over the radio to report a zero cab signal. OCC may authorize an operator to continue in Yard Mode which overrides the cab signaling system. Yard mode restricts the train to no more than 15 miles per hour. This restricted speed is a speed which will permit the stopping of a train within half the range of the operator’s vision, short of other trains or obstructions.  Operators are trained to proceed cautiously while operating a train in yard mode.

I also found out that Metro does not use automatic operation of trains.  All MetroLink trains are operated manually by the train operator, and a train will not move unless the operator has told it to do so. This way, should some malfunction in these systems arise, the operator is in control of the train. Being a light rail system rather than a heavier subway system, and with only two cars per train, MetroLink trains are also easier to stop in an emergency.

These are the precautions that we have taken in order to move people as safely as possible. If you have any additional questions regarding the safety features of MetroLink trains, please do not hesitate to post them here.

Metro Lifestyle

10 thoughts on “How do MetroLink trains stop safely?”

  1. Jimmy Z says:

    It appears that the Washington accident was a combination of a failure of the automated system and limited sight lines – the train in back was coming around a curve, reducing visibility and (obviously) not leaving enough time to stop. Operating a train is much like driving on ice – hit the brakes, even under the best of conditions, and it takes much longer to stop than it would in your much-lighter private vehicle with rubber tires on dry pavemment!

  2. Suzanne says:

    Jimmy — you are absolutely correct. It does sound like a combination of failures contributed to the incident in DC. Coming around the curve would reduce visibility and make it harder to stop quickly which is hard to do on rails! One of the articles I read about their incident, discussed how they have had problems with some of the old track relays that gave false indications. Our track circuits are much newer since our system is much younger and are designed for fail-safe operation just like all railroads.

    If a MetroLink circuit fails the operator receives the zero cab signal as well as a Red STOP signal if they are at an interlocking. This stops our trains and the operator has to physically override the system to keep the train moving, and then can only move the train 15 mph. No system is perfect, but we continue to look for ways to make things safer and eliminate as much human error as possible without leaving everything up to a computer!

  3. Steve says:

    So I hear that audible alarm ALL THE TIME when I ride Metrolink. At least I’m pretty sure that buzzing whine is the speed alarm since the train always slows, if briefly, every time I hear it and then accelerates when it ends.

    I love riding Metrolink, but here’s my question: why is the speed alarm so ridiculously loud and annoying in the passenger portion of the train? Along with not having recorded/automated station announcements (there are apparently 37 different ways in which to tell some to transfer trains for the airport! – some good, some awful) the buzzing speed alarm is the worst part of my daily trips on Metrolink.

  4. Suzanne says:

    Steve — you hit on 2 topics we are working on this year with operators to improve!

    I hate the ALARM too! I will check with the maintenance team to see why it has to be so loud in the passenger section of the train. We are working to reduce the overspeed alarms this year during recertification training as the operators are driving and evaluating each other on this as well as other passenger concerns. The buzzing not only annoys passengers, but the stopping and starting gives for a less than smooth ride.

    The announcements are another common complaint among passengers. We do give the operators standard announcement formats to follow, but operators tend to find their own comfortable phrasing as they are in the seat 40 hours a week. We do have some work to do before we can get to automated announcements — but it is somewhere in the future.

    Thank you for the feedback and I will pass it on verbatim to the operators! If you could — what is your favorite of the 37 ways to tell someone to transfer trains for the airport?

  5. 63101 says:

    It’s not really so much the phrasing of the train announcements that is the problem; it’s that operators do not always speak their announcements clearly and audibly. It’s hard to hear things over the general noise on the train when the operator does not enunciate their words.

    The worst example I ever encountered was a particular operator who would always literally shout the name of the station into the PA, and then trail off mumbling the rest – you’d hear “GRAND!!!! station” loud enough to make you jump a little, but then barely follow what buses you can catch from there. I have not heard him in a while, however, so I assume that issue was either brought to his attention or he is no longer in the front seat anymore.

    I’ve also occasionally heard people say things like “this is a westbound train to Shiloh-Scott.” I find it hard to fault someone for that, as I’d do the same thing every once in a while if I had to recite the same script as a full time job. However, it is confusing and could be solved by standardized automated announcements.

  6. Matt says:

    Part of the problem several of you have mentioned is a lack of good communication channels. If a rider such as you finds something wrong with the system, the main outlet is to call our customer service. We realize the need for a more comprehensive system for riders to provide their input on how the system works. I’m working with our Planning department to help develop such a system. We’re also working on intraagency communication – our bus / train operators, transit service managers, and maintenance people do not have good opportunities to communicate their ideas and observations to people at headquarters. We’ll be conducting interviews with such employees, and eventually move out into a new public communications effort.

  7. Suzanne says:

    All of the comments that come into customer service are routed to the appropriate operational management team to review, investigate where appropriate and respond to. Customer Service is very accommodating and provided me a full report of every MetroLink customer service call last year. We used the information to help us plan our recertification training with operators. The operators receive the feedback good or bad regularly when it occurs, and we are reinforcing some of the central themes of passengers as part of their annual training. This includes being careful of when you open and close doors, making clear announcements, operating for a comfortable and smooth ride and being attentive to special customer needs (ADA, Elderly, children).

    As with any company, we continue to work on improving communication channels (from the field to HQ and back) — but please know your comments and calls are heard!

  8. Melissa says:

    I actually really like the differing station announcements–they give each individual ride some character. What could clear up some of that confusion is an LED sign that displays the name of the next stop. They have them in Boston and New York, and I always find that immensely helpful. But that sort of thing probably costs a lot of money…

  9. Steve says:

    Suzanne (post #4): I know it’s not simple or easy, but inaudible and mumbling announcements are the biggest problem. As another person mentioned I do sometimes like the different announcements. The worst are all the different ways people announce transferring to-from the red-blue lines. Here are a couple examples: “If you need to go to the airport you must switch trains and board the Red Line to Lambert Airport.” Not bad. “If you’re goin’ to the airport you must switch trains and get on another train at the next station. Look for a red sign on a westbound train that reads “airport”.” That’s getting a big silly. The worst are the operators (and I suppose they’re just trying to be helpful) that after a couple announcements just start shouting, “if you’re going to the airport you’re on the wrong train!” I’ve seen this happen a couple times when people were coming from the airport (with luggage) and boarding the westbound blue line. They would be told a couple times that they’re on the wrong train! The other couple instances of real shouting that you should probably be aware of are the couple times I’ve seen someone get on the train with a bicycle in the middle of the car and when I’ve seen someone taking a picture of the train. I understand that there are rules, but why keep shouting “YOU NEED TO GET OFF THE TRAIN AND MOVE YOUR BIKE TO THE FRONT” while 200 people stand there and wait? Or “YOU CAN’T TAKE PICTURES. STOP TAKING PICTURES OF THE TRAIN!” Give me a break!

  10. Suzanne says:

    Thanks for the specific feedback. No question that the inaudible and mumbling are the worst of the announcements. We continue to reinforce this with operators as there are people on the train that NEED the announcements or are listening for something specific since they are less familiar with the system than you and I. The yelling at passengers is never good and is frustrating even for those passengers that are not being yelled at. We will continue to work on it. Thanks

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