[PRCo] Re: Transit Speeds

[Boris Cefer]

Max speed for streetcars in CZ is 60 km/h with limitation to 50 km/h on city 
streets, which is also a limit for rubber-tired vehicles.

B

----- Original Message ----- 
From: "Jim Holland" <PRCoPCC at P-R-Co.com>
To: <pittsburgh-railways at dementia.org>
Sent: Tuesday, October 23, 2007 12:04 PM
Subject: [PRCo] Transit Speeds


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.