Hiawatha Stoplights (was Re: [Mpls] Personal Rapid Transit)

[Sheldon Mains]

>  Perhaps someone else 
> on the list can find a citation to the article or another 
> source of information.  I believe that there is actually some 
> inadequacy with either the signal actuation, or sensing that 
> makes effective coordination of train and auto traffic 
> impossible without substantial additional investment.
> 

>From a variety of news reports and conversations, I understand there are a
variety of things causing the problems:
1. The trains are running slower than designed because people didn't want
the horns blaring (Federal law requires the train to sound horns at each
intersection above a certain speed.  Below that speed they can use bells.)
The sensors on the track that start the traffic light sequence were located
assuming a faster speed.  So the sensors have to be physically moved to
correct for the change in speed and reduce the length of the cycle.

2. Trains are tending to be at stations longer than designed.  This
lengthens the cycle (people who ride the LRT should try riding the Chicago L
or the DC Metro to understand that you start moving to the door BEFORE the
train stops!!) (sorry-- a sore point of mine).  I think the software is
being adjusted to account for this.

3. The software will be changed so that the walk cycle will only happen if a
pedestrian actually presses the button (It is now automatic on all cycles)

4. I think a previous post was partially right: While there are vehicle
sensors in the road, they do not seem to be used to adjust the cycle timing
(especially on the left turn lights).

5. It turns out that it is a lot easier to manage a joint rail transit/car
right of way if the rail is down in the median of the roadway, not off to
one side.  This is a design trade-off.  Stations are more accessible if they
are on the side of the right-of-way.

6. An extremely tight budget resulted in not enough computer modeling before
the thing started.  (Forcing public projects to do things at the lowest cost
possible does have its own costs)