DC Metro fatalities

[BaltACD]

DC Metro had another incident resulting in fatalities....

http://weblogs.baltimoresun.com/news/traffic/2010/01/what_is_it_with_the_washington.html

[aegrotatio]

 This time a hi-rail truck hit two workers replacing a transponder on the surface tracks at around 1:45 AM.  No train was involved, but we are losing our minds here in DC trying to understand how things could have possibly gotten so bad after being so good for so long.

 

And, if I may, this total nonsense that the automatic train control system is encountering situations that AIRINC and friends say have "never seen before" and must be monitored by an AIRINC-designed "overlay" system that nobody has ever built before is just a fine example of the new stupidity at WMATA and I'm ashamed at AIRINC for proposing and building this new "overlay" system instead of fixing the original system which had no problems.

 

[oltmannd]

aegrotatio

And, if I may, this total nonsense that the automatic train control system is encountering situations that AIRINC and friends say have "never seen before" and must be monitored by an AIRINC-designed "overlay" system that nobody has ever built before is just a fine example of the new stupidity at WMATA and I'm ashamed at AIRINC for proposing and building this new "overlay" system instead of fixing the original system which had no problems.

Well, yes and no. If I understand the stuff I read about the Metro, there are two systems in use. One is the basic, fixed block, cab signal based safety system and the other is the transponder and computer based supervisory control system. The cab signal system is supposed to keep the trains separated. It will apply the brakes to reduce speed if a more restrictive signal is passed. .e.g go by a stop signal and the train brakes will apply to stop the train. The problem was/is, the braking systems on the trains couldn't always stop the train in the required distance when wheel/rail conditions were bad. There are three fixes for this problem. 1. FIx the train braking system. 2. Lengthen the fixed blocks. 3. Reduce the speeds allowed for each signal indicaiton. Metro chose option #4. Reduce the maximum speed allowed by the supervisory control system. The problem is, this is not a SAFETY system. It can get things wrong. Sounds like ARINC is proposing an overlay to make it safety system.