Abstract: Road fatalities are complex events involving a variety of factors, including highway geometry, driver behavior, weather conditions, speed limits and human factors. As the number of accidents increasing day by day the design consistency evaluation is becoming more significant. Geometric design consistency is an important component in highway design and an important tool in evaluating road safety. Mainly design consistency depends on four factors. They are vehicle stability, operating speed, and driver work load and alignment indices. Operating speed method is the more common method for evaluating the consistency of highways. The operating speed of a highway is the speed at which motor vehicles generally operate on that highway. The geometric characteristics of plain terrain, two lane rural state highway road of Kerala, has been assessed to understand the effect on the operating speed of vehicles. Vehicles considered in the model is 2 wheeler, 3 wheeler, light motor vehicle, LCV & MCV. The effects of design elements such as horizontal and vertical curves, lane width, shoulder width, super elevation, median width, curve radius, sight distance, etc. on safety will be taken. Research related to geometric characteristics showed that few variables have significant effect on the safety of roadways. The relationship between operating speed and road geometric design is examined through results of studies made in different localities. Statistical modelling approaches by SPSS software is used for model development.

Keywords: Geometric elements, Operating speed, Design consistency, SPSS software