Masdar City, near Abu Dhabi in the UAE, set out to be a sustainable, zero-carbon, zero-waste community. Part of the premise was to exclude automobiles entirely. The city was going to rely mostly on a personal rapid transit system for internal mobility. A PRT system with some 80 stations and thousands of vehicles was planned. Unfortunately, recent (October 2010) announcements indicate that this plan has now been scaled back and the PRT system will be confined to a pilot system or a small system serving the area close to the Masdar Institute of Science and Technology. This is a blow to PRT proponents, but is PRT to blame for the setback?
Since PRT does not mix well with street level traffic, most urban plans call for an elevated PRT system with a very small ground-level footprint. This was considered at Masdar, but there was a chicken and egg problem. If the PRT was built first, it would be difficult to integrate it in the buildings to follow. Worse, all the costs would have to be borne by the developer. If the buildings were built first, they could be planned to accommodate and integrate the PRT system, and the building developers could possibly absorb station and other costs. Building developers were slow in coming forward and so the latter, preferable, option was not feasible, although it could possibly still have been accomplished by imposing carefully-planned building requirements (not easily accomplished in the prevailing culture). This, coupled with a desire to provide a pedestrian-friendly “ground” level, led to the decision to raise the pedestrian level, some 7 meters above the ground level to form a “podium” level, and to build the PRT system and the utilities in the undercroft formed below. Future buildings could then be constructed on the podium level with few restrictions.
Putting PRT in the undercroft has proven problematic because:
- The PRT routing was constrained to follow surface street routing, which is deliberately discontinuous to help prevent windy conditions.
- The PRT routing is the same as that for special delivery (and, possibly, emergency) vehicles – violating one of the principles of PRT, which is to separate it from other traffic.
- There is no way of enticing building developers to share the costs of the PRT stations and other elements.
The podium decision was made in more prosperous times. It is an expensive way to build a city, and current economic considerations have resulted in the decision being made not to extend the podium concept and the PRT system throughout the city. Thus the podium/undercroft decision underlies the decision not to extend the PRT system. Hopefully, the PRT system will soon come into successful public service, indicating that it can at least do the first part of what it was acquired to do.
Masdar is apparently considering electric cars and/or buses instead of the PRT system. It is difficult to imagine how this can be accomplished without revisiting the design parameters for the streets which are narrow and discontinuous. It may make much more sense to take a hard look at how an elevated PRT system could work and what it would take to merge it with the undercroft system.