4. Smart technologies
Smart technologies in Singapore's transport system can be broadly categorized into four divisions according to their primary functions: control systems, monitoring and enforcement systems, information management systems, and revenue management systems. Note that the classification has been done at the city-level. The user-level technologies which do not require an infrastructure, such as the smart vehicle control systems, collision avoidance systems, and the driver safety monitoring systems are left out. In subsequent sections, key smart technologies in the four divisions are summarized whereas a detailed description of these technologies could be found in Debnath et al. (2011).
4.1. Control systems
Singapore land transport system has adopted many smart control systems that manage traffic flow efficiently using automated traffic signals like Green Link Determination System (GLIDE), B signal, countdown signal and intelligent road studs (see Fig. 5). GLIDE is an adaptive traffic signal system that continuously collects traffic data (through detection of vehicles and pedestrians) and automatically allocates signal timing based on traffic volume along each direction of an intersection while allowing signal coordination along a corridor (OM, 2011). Some intersections are also equipped with a transit signal priority scheme (i.e., B-signal) which detects approaching buses and facilitates their movements by extending green time as well as turning on the B-signal to allow an earlier start. Detection technology of some traffic signals enables the recognition of elderly pedestrians via tapping of senior citizen concession cards, and helps to allocate an extended green period for crossing. Some are also equipped with countdown timers and audio signals to aid respectively hear-impaired and vision-impaired people. Another recent improvement is the installation of intelligent road studs at 17 major intersections (OM, 2011) which alert motorists about the presence of pedestrians by blinking the studs on pavement.