Integration Of Ato Signals For Red And Orange Lines

Do these signals used can be integrated into a single system?

Can you please rephrase this? I'm not sure anyone knows what you're trying to ask.

In reality, the red and orange line systems use the same wayside equipment, and mostly the same on-car equipment.

The big difference is the shorter distance between stops on the southwest section of the Orange Line, where running speeds are therefore slower. For that reason you get fewer enforced slowdowns than on the Red Line where there are long stretches of 40 and 50 codes. The runs from Sullivan north are almost entirely 40 codes with no curves to slow things down to 25. The southern section is a mix of 25 and 40 codes, but manual slowing for stations takes most of the edges off the changes.

The Red line was designed for 45 mph on most sections and 35 on curves, but is limited to 40 and 25 by the codes. Originally the 35 mph sections were protected by time signals, which could be triggered by judicious coasting. Now the slow sections are enforced well in advance of the old time signal locations, causing very noticeable penalty applications at locations like the bottom of the tunnel from Broadway to South Station and around Freeport St. heading for Fields Corner. Another problem is the sharp curve at Harvard which is the equivalent of the old 90 degree curves on the el structures. This was because the MBTA took the cheap way out at the design stage, rather than opting for a long sweeping curve at a deeper level.

Both lines are subject to phantom stop codes, where the receiver on the cars loses the signal from the rails. This results in an emergency application and a mandatory delay while the emergency pipe recharges.

There is a phantom stop code on the Orange line at Tufts (formerly New England) Medical Center for years. I forget which side it's on, it could be both sides, but the train receives a random stop code (or loses signal) and stops just short of entering the station. I've seen them do the same while exiting the station (train stops after about 2 cars go into the tunnel, leaving 4 cars on the platform) where the air just dumps and they sit for a minute before the train can leave.

diburning wrote:There is a phantom stop code on the Orange line at Tufts (formerly New England) Medical Center for years. I forget which side it's on, it could be both sides, but the train receives a random stop code (or loses signal) and stops just short of entering the station. I've seen them do the same while exiting the station (train stops after about 2 cars go into the tunnel, leaving 4 cars on the platform) where the air just dumps and they sit for a minute before the train can leave.

I've definitely seen trains dump upon leaving Tufts northbound and Chinatown northbound. And, most infamously... Between DTX and State, heading northbound. It seems as though trains are more likely receive a penalty between DTX and State than they are to proceed unhindered.

They use the same company as the WAMTA and a few others transit systems for ATO/ATC. Not sure if many of you remember the unfortunate accident on WAMTA (Washington DC Metro) outside of Totten Pond Road where a train which was following its leader. The train left Totten Pond station with a restrictive speed signal, then continued on the signal became clear to the trains ATO/ATC rounding a blind curve slammed into the rear of the leader, killing 6 including the motorperson as the train telescoped on the last car of the train, who had a stop code on the leading train but due to some electrical issues with the WEZE bonds. They discovered that some transient electrical waves caused the ATO/ATC not to functioning and caused the lead train which was stopped but didn't put out a protection on the ATO/ATC/ATP system so the follower got a clear signal and not a stop or restricting signal, cause it was hidden electronically from the follower. After the accident the NTSB placed an emergency notification to all transit systems were told to stop using the ATO/ATC/ATP until all the signal system was gone over with a fine tooth comb. So for approx. 2-5 days the red line was running manual blocks until the system was checked and recertified. Sorry for the long story

I like what New York does. If the cab signal system is operational the wayside signals flash. Thus if you get a good code and a flashing red - you get tripped. On the other hand a flashing green and a "Stop Code" means you got a bad code. That may change when the Flushing line is converted…

Personally I think cab signals and ATO have no place on rapid transit.

Gerry6309 wrote:The Red line was designed for 45 mph on most sections and 35 on curves, but is limited to 40 and 25 by the codes. Originally the 35 mph sections were protected by time signals, which could be triggered by judicious coasting. Now the slow sections are enforced well in advance of the old time signal locations, causing very noticeable penalty applications at locations like the bottom of the tunnel from Broadway to South Station and around Freeport St. heading for Fields Corner. Another problem is the sharp curve at Harvard which is the equivalent of the old 90 degree curves on the el structures.

Why didn't they design the curves and the speed codes to match?

Fortunately southbound trains are allowed to pull into the Harvard platform at a decent speed despite the curve just after the station, and only have to keep it to 9 mph once they start moving again.

Something I've asked several times: after the 2010 Alewife derailment, they lowered the speed to 10 mph for diverging moves through the crossover. This made a bad chokepoint even worse -- there are long backups getting into the station at rush hour. Why is this crossover unable to handle the 25 mph speeds it used to handle, which are common in other places on the T and on other subway systems?

Gerry6309 wrote:Personally I think cab signals and ATO have no place on rapid transit.

I'm curious, what do you feel would be a better solution?

Finch wrote:

Gerry6309 wrote:Personally I think cab signals and ATO have no place on rapid transit.

I'm curious, what do you feel would be a better solution?

Wayside signaling with automatic train stops would be fine.

Gerry6309 wrote:

Finch wrote:

Gerry6309 wrote:Personally I think cab signals and ATO have no place on rapid transit.

I'm curious, what do you feel would be a better solution?

Wayside signaling with automatic train stops would be fine.

Amen!

ATO is a marginal idea in theory, but in practice it seems to combine the worst of both worlds in terms of automation vs human error. Wayside w/ failsafes is a great option, and fully automated seems to do a decent job as well, especially if you have a conductor on board to manage doors, etc.

Gerry6309 wrote:

Finch wrote:

Gerry6309 wrote:Personally I think cab signals and ATO have no place on rapid transit.

I'm curious, what do you feel would be a better solution?

Wayside signaling with automatic train stops would be fine.

Nobody's going back to old mechanical tech. Even PATH and NYC Subway are accelerating their CBTC rollouts because of how many trip stops and heaters got fried during Sandy. It's too maintenance-intensive, and in addition to the service-enhancing side of CBTC (if it's programmed that way) the large reduction in the amount of trackside hardware and replacement with solid-state electronics and radio frequencies saves money over waysides + train stops over the life of the installation. In addition to not being as easily ruined in a 50-year flood event.


If the T goes for CBTC, Blue will be the first one to get it even if Red needs it worst to fix the headways. For the same reasons...it's less maint-intensive for sitting out there in a flood plain.

What does CBTC stand for, please?

MBTA3247 wrote:What does CBTC stand for, please?

Take your choice:

Communication Based Train Control

or

Crap Being Thrown Casually

F-line to Dudley via Park wrote:

Gerry6309 wrote:

Finch wrote:

Gerry6309 wrote:Personally I think cab signals and ATO have no place on rapid transit.

I'm curious, what do you feel would be a better solution?

Wayside signaling with automatic train stops would be fine.

Nobody's going back to old mechanical tech. Even PATH and NYC Subway are accelerating their CBTC rollouts because of how many trip stops and heaters got fried during Sandy. It's too maintenance-intensive, and in addition to the service-enhancing side of CBTC (if it's programmed that way) the large reduction in the amount of trackside hardware and replacement with solid-state electronics and radio frequencies saves money over waysides + train stops over the life of the installation. In addition to not being as easily ruined in a 50-year flood event.


If the T goes for CBTC, Blue will be the first one to get it even if Red needs it worst to fix the headways. For the same reasons...it's less maint-intensive for sitting out there in a flood plain.

Sadly, the one way to make such electronic equipment reliable is to keep it away from vibration, voltage spikes, steel dust and other things found in subways. The Red Line ran like a top until the ATO Virus started to spread in 1980. The MBTA didn't feel it was fair to keep all the signal failures restricted to Quincy and Braintree Passengers. Even the 1975 pileup outside Park Street was the result of broken rules, not broken equipment. It has never worked right, and it never will give us the smooth ride that a well trained motorman obeying the rules can give without interference by arbitrary slowdowns.

Sorry F-Line we will never agree on this one. Sadly, I am old enough to remember the 01600s running without such interference when they were new.