Saturation flow rates of heavy vehicles from rest at intersection

The objective of this research project was to measure and quantify the acceleration of heavy vehicles from a stopped position at signalized intersections, and compare the acceleration pattern with that found in traffic simulation software that is currently used. This information can be used either to validate existing software or provide a basis for changing the default values in the software.;Heavy vehicle acceleration data were collected at five level intersection approaches with a heavy vehicle component in a Northwest Arkansas urban environment. Predictive speed equations were derived from the data and the predicted speed values obtained from the equations were compared with the actual average speeds. Using the actual average speed data of all heavy vehicles, acceleration values were produced using a formula based on a given distance and the velocity of a vehicle. Based on these values, an adjustment to the default acceleration curve in VISSIM was performed. It was observed that the adjustment of the default acceleration curve yielded an acceleration curve pattern lower than the default acceleration curve. After adjusting the default acceleration curve values to the new values, a sample VISSIM model yielded results that reflected the sluggish attributes of heavy vehicles from full stop at a signalized intersection.