What is an Interchange?
An interchange is a grade-separated intersection (one road passes over another) with ramps to connect them. For busy roads this is a necessity to keep traffic moving. Traffic signals are sometimes needed to help traffic move through and between the two facilities. Within these pages, we are going to depict and describe some of the various interchanges used to date. There might be some not used in Ohio. All interchanges are designed for the projected traffic for the region. This will make some designs more beneficial than others with respect to operation, right-way impacts, etc.
A complete interchange has to provide access to and from any direction from each facility. Full freeway to street access with a conventional interchange requires a minimum of four ramps, to get on and off in each direction. In Ohio, full interchanges are required for a future design. Partial interchanges are not allowed unless special needs are displayed (park and ride, by-pass routes, etc.)
An exit ramp, or off ramp, leaves the main roadway for another road; an entrance ramp, or on ramp, enters the roadway. These terms make the most sense when one freeway intersects a surface street; entrance and exit are from the point of view of the freeway.
An interchange is a simple solution to a capacity problem. Safety, cost, environment, development and politics can vary at each site. Many interchanges are slight variations of a few basic types.