DECISION MAKING PROCESS OF TRAFFIC CALMING DEVICES: A Comparative Study

Traffic calming is a way to reduce through traffic volume and high traffic speed into local residential streets. Although many countries install traffic calming devices but many do not have design guideline or systematic process to carry out traffic calming schemes. Japan is one of the countries which does not have well defined and systematic study procedure to carry out the traffic calming process. The objective of this research is to perform a comparative study of traffic calming decision making process, which is expected to serve as a basis for introducing in Japan as well in some communities where there is no traffic calming process guiding principle is available.A mail based questionnaire survey of North America and some European countries was conducted to know the traffic calming process and types of devices currently in use. Interview survey was carried out to Sacramento (California) and Largo (Maryland) USA. Both of the surveys were conducted to the decision making authorities. The interview survey contents include the description of the traffic calming process and issues, question and answer and sight visit to see traffic calming devices presently used by them. From the interview survey it was found that in order to determine the residents' supports different city has different type of voting process. Sacramento has two step voting process to evaluate residents support. The purpose of first step voting is to select a device and second step is to whether to install the device permanently. To evaluate residents' requests and to implement decisions for the traffic calming, ranking system is used by different cities on the basis of priority. From the questionnaire survey it was found that about 72% of the projects were prioritized by point scoring system, 14% of the projects were prioritized by engineering judgments, and 24% of the projects were prioritized by other criteria.