Why do s/b Westside Expresses slow down heavily at Canal St?

[Deucey]

T4R

[RR503]

~~~Timers~~~

IIRC there was some derailment on the crossovers down there waaaay back in the day (1960s?). That, and the curve entering Chambers provided sufficient justification for some heavy timer installation, leading to the ridiculous slowness we see today. 

[trainfan22]

They don't want motormen overshooting the home ball signal.

[Deucey]

2 hours ago, trainfan22 said:

They don't want motormen overshooting the home ball signal.

Home ball signal?

[trainfan22]

32 minutes ago, Deucey said:

Home ball signal?

Its the double signal right before a switch. Like in the photo below, the signal on the right hand side to be specific.

 

 

 

[Jemorie]

The timers are justifiable, whether you agree with me or not. The only thing is that they shouldn't start so early at midway out of Canal Street, but rather at the north end of Franklin Street. The curve between that station and the crossovers before Chambers Street southbound is why southbound West Side express trains should be careful.

[CenSin]

8 hours ago, Jemorie said:

The timers are justifiable, whether you agree with me or not. The only thing is that they shouldn't start so early at midway out of Canal Street, but rather at the north end of Franklin Street. The curve between that station and the crossovers before Chambers Street southbound is why southbound West Side express trains should be careful.

It’s only justifiable because of human operators. This overabundance of caution is to account for a huge margin in variability of human performance. With CBTC, the slowdown can be fine-tuned to keep the train at the right speed only where the slowdown is needed.

[RR503]

2 hours ago, CenSin said:

It’s only justifiable because of human operators. This overabundance of caution is to account for a huge margin in variability of human performance. With CBTC, the slowdown can be fine-tuned to keep the train at the right speed only where the slowdown is needed.

Exactly. Timers in these sorts of areas are as you say defensible — if we assume they’re installed/maintained well. In the current environment, where GT35 could mean GT20, those timers create the very variability that you talk about as operators treat the signals/potential consequences differently. 

I also think that it’s worth noting that not all timers are related to track geometry. Many areas were timed to mitigate the danger posed by ineffective brakes back in the 90s. The logic was that if your control line is too short to stop a train moving at maximum speed, then reduce said speed (or extend the CL, or in cases both). This of course markedly reduces system capacity, as the speeds/accelerations/decelerationsthe signals were designed around are all reduced — something that contributes greatly to the levels of unreliability seen these days. 

I’ll let the fallacy of neutering speed to compensate for substandard brakes speak for itself... 

[MHV9218]

On 8/25/2018 at 4:03 PM, CenSin said:

It’s only justifiable because of human operators. This overabundance of caution is to account for a huge margin in variability of human performance. With CBTC, the slowdown can be fine-tuned to keep the train at the right speed only where the slowdown is needed.

That said, I resent the notion that T/Os have to be treated like morons. There isn't, historically, that much variability. This is a skilled profession, it takes training to learn it, and it pays like a skilled profession. T/Os had excellent safety records for a half century without even running speedometers in their cabs, and now we have to act like hands have to be held everywhere? T/Os are much more skilled than the beancounters give them credit for, and if anything the answer is more training, not more timers. Those penalize everybody, especially the talented T/Os who do fine without them. With proper car maintenance, this system could easily run without any timers and there wouldn't be a single accident, but we'll never see that day.