Evaluation of ITS Technology for Bus Transit Systems

Problem

Recently, bus transit service providers have begun to adopt Intelligent Transportation Systems (ITS) technologies such as Global Positioning Systems (GPS) and Mobile Data Terminals. These systems taken together have the potential to reduce the cost of providing transportation services through the execution of real-time control strategies, performance monitoring systems and data collection to support service realignment. This research evaluates bus control strategies using ITS against those without ITS. Two levels of ITS are considered: 1) a system with centralized tracking, and 2) a system with information on connecting passengers, as well as centralized tracking. For those strategies using ITS, we develop methods to forecast bus arrival times to a stop and the number of passengers on board the bus.

Findings

Several different ITS strategies were evaluated. In terms of minimizing the average passenger trip time, the ITS strategies outperformed the non-ITS based strategies for the random generated problem sets, though not for one real-life dataset.

Overall, the researchers found it disappointing that ITS did not provide larger time savings in the analysis conducted for this research. A fundamental reason for this is that in many situations, it is optimal to either have a bus leave immediately whether or not connecting buses have arrived, or to wait as long as possible until all connecting buses have arrived. These extreme cases require no communication and no ITS.

ITS was found to be more beneficial for cases in which a connecting bus incurs a small delay and it is more advantageous to wait for its arrival than to depart without the connecting passengers.

The savings per passenger appear to be no more than 1 minute, which translates into annual time savings on the order of 500 to 2000 hours per bus. Savings of this magnitude may be sufficient to justify installation of an ITS system with payback within a few years. More generally, the savings are highly site-specific and should be evaluated on a case-by-case basis. Cost-benefit analysis was not performed as part of this research.