Urban Traffic Speed Management: The Use of GPS/GIS

The prevailing traffic speed at any section of a roadway affects the quality of traffic at the time. Whereas excessive speeds affect the severity of road traffic accidents, crawling speeds in the urban environment is also indicative of congestion. One of the key elements in speed management planning is the functional classification of roads by speed. For example, 30km/h has been designated for residential areas and 60km/h and above for major arterial roads. Nowadays, efficient vehicle monitoring can be achieved by integrating Global Positioning System (GPS) derived traffic data such as vehicle speed and direction of traffic flow into a Geographical Information System (GIS) environment. This GPS-GIS integrated system provides real-time meaningful location and status of the vehicles in the network. The system has been used to show the second-to-second positional changes in speed and directions of vehicles travelling in Kumasi, the second largest city in Ghana. Using the geographic components in a dataset and visualizing the results in a map provided a clearer picture of the traffic-state of every route in the network. The GPS has clearly indicated the road sections where speeds are unacceptable and driver behaviour is affected giving transport planners the option to choose the desired speed management technique to improve the traffic system. 1