The way ahead for London's bus priority at traffic signals

Recently, Transport for London (TfL) has procured a modern Automatic Vehicle Location (AVL) system for fleet management, passenger information and bus priority. The new system is known as iBUS and is based on GPS and supporting technologies for bus location. In this system, bus detector locations are configured in the on-bus computer and hence are also known as "virtual detectors". The predefined virtual detector coordinates are compared with the location of the bus obtained from the on-bus navigation system to trigger a priority request. The request is made through radio messages from each bus to the traffic signals encountered en-route. This system eliminates the need for on-street hardware for detecting buses and requesting priority. Hence the incremental cost of installing bus priority at signals is much lower than with the existing system and the location of detection points is more flexible. This has prompted TfL to plan to extend bus priority to most of the traffic signals in London. Apart from reduced cost, the system also provides facilities to allocate up to four detection points to each bus movement at an individual junction. This provides an opportunity to enhance bus priority considerably through improved methods of control giving potentially greater benefits. This paper presents some of the methodologies studied to enhance bus priority at traffic signals using the iBUSusystem. For the covering abstract see ITRD E140665.