[PRCo] Transit Speeds

[Jim Holland]

Some comments to deepen the understanding of Transit Speeds.

Here in SF the  MAX  speed for any Transit vehicle On The Streets is 
25-mph or the posted speed limit  --  WhichEver Is  *Lower.*     Transit 
vehicles should slow to 15-mph for each and every intersection  --  
Defensive Driving to prevent accidents Even If it would be the fault of 
the other vehicle.

Late last night around MudNight on my TrolleyCoach, I was traveling at 
25-mph and pushed it up to 30-mph  --  *Seemed*  like I had doubled the 
speed and the bus  *Seems*  more like it is doing 50.     Getting a bus 
up to that speed will require  *about*  a block to slow and stop it 
using full service braking  --  on a PCC that is a max of 4.75-mphps 
deceleration  --  on our ETI TCs we use pure dynamic until the bus is 
almost stopped and then we push the brake a little more to complete the 
stop and hold the coach.

We had a discussion of average transit speeds which figures in 
everything the vehicle does from the moment it starts at one end of the 
line until it reaches the other end of the line  --  dwell times at 
traffic signals and for passenger boardings and alightings are included 
in this time.     On the Interurbans it was in the 16- 18-mph Average 
Speed end to end.     In light of this, traveling at 18-20--mph through 
the tunnel for 3/4-mile without interruption helps to improve the 
Average Speed.

Considering All The Potential Traffic in that tunnel, and the fact that 
it is 6% Downgrade, that a TrolleyCar is a large lumbering vehicle and 
slow in braking compared to many other vehicles, that passengers are the 
cargo,  what at First Blush does seem to be a Very Slow Speed  --  (My 
Reaction Was The Same, Boris)  --  actually works out to be Extremely 
Reasonable and maybe on the High Side for Traffic Density.

Others may be able to add more observations to increase our 
understanding of the limitation of transit vehicles.     As I thought 
this speed restriction through with comparisons to other transit speeds 
and safety issues it helped me appreciate this limitation on speed.     
PRCo was Very Big On Safety and this understanding has been deepened by 
many of the comments here on the list which have pointed out various 
steps PRCo took concerning safety.     This speed limit down through the 
tunnel is another.

Someone mentioned something similar for the Smithfield St. Bridge.




> Edward H. Lybarger wrote:
>
> That's what they wanted...it is a 6% grade downhill!
> -----Original Message-----
> From: Boris Cefer
>
> That means approximately 18 mph. Pretty slow.
>
> B
>
> ----- Original Message -----
> From: "Edward H. Lybarger" <trams2 at comcast.net>
>
> It's a "Time in Motion" restriction. Operators are required to consume 
> 2 1/4 minutes traveling down through the tunnel. This is how they 
> specified speed limits without having speedometers on the cars.
>
> Ed
>
> -----Original Message-----
> From: ROBERT R ROCKWELL
>
> What does the "2 1/4" sign mean in this tunnel entrance?
>
> Robert Rockwell