Feds to Investigate MBTA Safety

The sill is the portion of the car's side that sits below the level of the floor and protects the actual frame from exposure to the elements. On the #12 cars, it's the beige piece below the orange stripe and door thresholds.

So the sill is really a cowl; basically non-structural cover.

Universal HUB reports another Red Line runaway from the Braintree yard this morning.

Fair use:

A two-car Red Line train came out of the Braintree yard when it wasn't supposed to around 5:30 a.m. and then didn't stop until it got about 800 feet north of the station, the MBTA reports.

Full article: This morning's massive Red Line delays caused by yet another train just rolling out of the Braintree yard

This is a new secret driverless mode they plan to roll out systemwide.

Reminds me of this earworm:

"Roll, roll me away, won't you roll me away tonight. I too am lost, I feel double-crossed and I'm sick of what's wrong and what's right.....

....And I said next time. Next time: We'll get it right"

The highlight of this most recent event is that there was actually someone on board the train: “On a recording of MBTA radio frequencies, the operator of the short train - consisting of older cars 1640 and 1641 - can be heard urgently calling to a dispatcher: ‘Sir, it's not stopping!’”

This latest incident sounds more like a brake failure than the previous sort of unattended runaways. Still alarming, just for different reasons.

We sure get variety when it comes to safety problems at the T...

Are there hand brakes on transit cars that can be manually screwed down? How do the emergency brakes that are in the passenger compartment work? Is there no dynamic braking? I assume the train was running down hill

What surprises me most is it delayed start of service for 45 minutes apparently. It shouldn't take that long to tow it back to the yard, maybe they were under orders not to touch until investigators arrived to supervise.

A two car train seems very short. I speculate that they were moving cars that were cut off yesterday to get them out of the way.

How was the 2 cars towed back? Several possibilities among others anothe 2 car train, aor truck with coupler, or track mobile among others?

All the subway cars do have a handbrake. Likely set the handbrake(s) and have another train couple on and tow backwards or if air pressure can be built up, run back to the yard after receiving permission and likely with inspector onboard.
No dynamic brakes on these cars in the incident below 15mph, which is standard for most subway cars without electronic motor controls.

I still don't get it on what happened, reduced brake capacity.

My understanding is that the air part of an air brake system holds the brakes off the wheel thread. When the emergency brakes are tripped the air is released and the brakes contact the wheels. When the TO applies the brakes entering a station part is dynamic above 10-15 mph then its all air brakes to a stop. In this scenario a hostler was doing a two car move and applied the brakes to find they had none to speak of. So this are the possibility:

1 - The air could not be released, hence no brake application. (Controller or brake valve problem.)

2 - Brake shoes worn down that they don't make contact with the wheel.

3 - Mis-adjusted brake slack adjuster or brake linkage not connected.

Looking at those three puts it in the house of poor maintenance. Lack of personnel, lack of training or just negligence. So, in a 6-car set how many brakes are needed?

I am not usually negative but this is getting trying.

You have the operation of the brakes backwards. The brakes are held off by springs. Moving air into the brake cylinder applies the brakes.

There is a major difference between "train air" and "straight air." Subway cars are straight air, wherein air applies the brakes. If there is no air, there are no brakes. Subway cars do employ a "brake pipe" referred to as train line pressure, but it does not function like a railroad brake pipe. Train line pressure simply holds valves closed to keep the train out of an emergency application. This way, if the train comes apart it allows the emergency valve to open resulting in an emergency application. Train air fills every car with air pressure and then controls that air with the brake pipe pressure.

While I don't know the specifics of the incident, we do know that it involved a disabled train. The most likely scenario I can come up with is a dead pair of cars were brought into the yard and uncoupled. After the uncoupling the cars began to roll and, because there was no air in the system as the cars were dead, there was nothing other than wrapping a probably fairly weak handbrake that the employee on board could do.

Whatever happened, it is very embarrassing. Fortunate that nobody was injured.

CRail wrote: ↑Wed Jul 27, 2022 5:14 pm There is a major difference between "train air" and "straight air." Subway cars are straight air, wherein air applies the brakes. If there is no air, there are no brakes. Subway cars do employ a "brake pipe" referred to as train line pressure, but it does not function like a railroad brake pipe. Train line pressure simply holds valves closed to keep the train out of an emergency application. This way, if the train comes apart it allows the emergency valve to open resulting in an emergency application. Train air fills every car with air pressure and then controls that air with the brake pipe pressure.

I stand corrected regarding the braking systems.