Saturday, December 14, 2013

Bus Rapid Transit through Light Rail: Curb and Contact Guidance


A full spectrum of options
Recent Developments in Public Transportation, Topic 1 part 2
Continuing the previous post, we're looking at systems for guiding Bus Rapid Transit and similar vehicles. Today, we'll explore contact-guided systems.
Snohomish Community Transit Swift bus
Note the "rub-rail" on the lower yellow portion
of the edge of the platform. Photo: L. Krieg

Contact-guided vehicles

There are a couple of solutions for guiding a vehicle by contact.
Station platform for Eugene, Oregon's EMX BRT
Here, the rub-rail is clearly shown by its yellow paint
Photo: L. Krieg

Tire-guided contact is when there is a "rub-rail" on the sides of station platforms to dock the bus accurately. The "rub-rail" allows the operator to feel positive contact through the tire to the steering wheel, but holds the wheel far enough away from the platform edge to prevent damaging contact to other parts of the bus (such as bumpers, lug nuts, or skirting). This system is used, for example, by Community Transit's Swift service in Everett, Washington.
Snohomish Community Transit's Swift BRT
The bus is docked with the tire against the rub-rail.
Note the size of the gap between platform edge and bus floor (3-4 inches):
A wheelchair would probably need the operator to deploy a bridge in order to cross the gap;
a stroller or walker could probably be maneuvered without a brdige.
Photo: L. Krieg

Contact guidance is only practical at very low speeds; otherwise, wear on the tires becomes expensive and even dangerous. For safe guided navigation in general, a small horizontal guide-wheel is used in contact with a curb or rail.
Mannheim, Germany: guide-wheel on BRT vehicle.
(Note also the protective casing for the lug-nuts.)
Photo: Martin Hawlisch
Wikimedia Commons
. Reproduced under the terms of the GNU Free Documentation License

These wheels can also be used solely for docking - for example, in Cleveland Ohio's Health Line service. For navigation, a rail or concrete lip is installed along the side of the bus lane, as in Adelaide, South Australia's O-Bahn; and the Cambridgeshire Guided Busway in England.
A bus on the O-Bahn Busway route in Adelaide, Australia.
Photo: “Beneaththelandslide”
Wikimedia Commons. Reproduced under the terms of the GNU Free Documentation License

Pros and Cons of Contact-Guided Buses
Pro Con
  • Simple
  • Inexpensive
  • Relatively accurate docking
  • Rub-rails: any contractor can easily install them
  • Rub-rail: Operators say they don't like striking curbs with their vehicle
  • Rub-rail causes tire wear
  • Rub-rail is only applicable for low-speed docking, not for  running in constrained or twisting lanes
  • Guide-wheel: must install steel or concrete guide-rail
  • Guide-wheel: may make unpleasant grinding noise
Cambridgeshire, England Busway
Concrete lip of trackway provides guidance
Photo: Bob Castle
Wikimedia Commons. Reproduced under the terms of the GNU Free Documentation License

To learn more:

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