Effects of Design Elements on Merging Capacity

A microscope model was developed to simulate traffic behaviour at grade separated interchanges.  The model was calibrated and validated from a large UK data base and applied to assess the validity of current ramp entry designs.  The significance of design elements such as acceleration lane length, slip road length and gradient was estimated, and it was found that current design practice for ramp entries is generally inadequate. However, some designs would seem to be "more adequate" than others and the results explore the effects of changes in key parameters.  (TRRL)