Optimum Turnouts Spacing Model in one Lane Two-Way Roads Using Intelligent Transportation Systems

Low volume local rural roads in Iran constitute 83 percent of countries’ roads network which have high initial construction and maintenance costs. Due to the specific topographic situation and low traffic volume (less than 400 vehicles per hour), most of these rural local roads do not need two lanes with the usual needed roadway width. Instead with a one lane two way specifications equipped with turnouts in determined spacing, these roads could have commensurate performance with their specific movement that also have acceptable traffic attributes. The most remarkable factor in these roads is minimizing the cars’ delays due to their stoppage in turnouts. For modeling one lane two ways roads equipped with intelligent transportation systems, computer simulation for modeling this type of road and performing related movement regulations have been used in this research. With the output results of the simulation process, regression model of turnouts spacing have been developed and the models’ parameters were statistically tested. Minimum delay for maximum road capacity with respect to determined values of turnouts spacing, total road length, permissible speed and turnouts capacity was calculated. In all different designated situations, minimum delay for maximum road capacity with respect to Poisson distribution of arrived vehicles number to the left and right origin in equal time intervals was 8 minutes. According to the results of this research increasing the turnouts spacing for one kilometer can reduce delay time for about 12 minutes.