The farther the service road is located from the main line, the less influence the two
facilities will have on each other. A separation width that exceeds the clear zone measurement
for each roadway is desirable. However, the separation should be at least
wide enough to provide normal shoulder widths on each facility, and also to accommodate
surface drainage and a suitable physical traffic barrier. Glare screen is desirable
to screen headlights when the service road is two-way.