Dynamic Junction Control utilizes traffic monitoring and overhead lane-use signals to control access to both mainline and ramp lanes at interchange areas where high traffic volumes are present and the relative demand on the mainline and ramps change throughout the day. The intent of dynamic junction control is to allocate roadway space that favors the highest volume. For example, when ramp volumes are relatively light or mainline volumes are very heavy, it might be most effective to have an entrance ramp merge into the right lane. However, there may be times that the volume on the ramp is extremely high while the mainline volumes are low. In this case, it might be most effective to “close” a mainline lane upstream of the ramp through the use of lane control signs in order to give ramp traffic near free-flow movement onto the highway, thus reducing the high potential for rear-end collisions on the ramp.
This approach has been implemented in Germany and the Netherlands, as well as the state of Washington, where collisions were estimated to be reduced by 20 to 25 percent. For these applications, mean travel time and vehicle hours of delay were reduced and mean travel speed increased for both the vehicles on the ramp and mainlines.
Dynamic Junction Control is currently being evaluated for implementation at interchanges that have an imbalance between merging and through traffic volumes (i.e., more vehicles enter and exit the roadway than continue through). These interchanges include I-76/U.S. 1/Roosevelt Expressway; I-76/I-476; and I-76/U.S. 202/U.S. 422.
