The American Association of State Highway and Transportation Officials (AASHTO) recommend that the length of a deceleration lane should be based on which of the following criteria?
1. Highway design speed
2. Grade of deceleration lane
3. Design speed of controlling exit ramp curve
4. Design speed of controlling entrance ramp curve
5. Deceleration characteristics of an automobile
6. Deceleration characteristics of a large vehicle
Explanation
Answer: A - AASHTO recommends that the length of a deceleration lane is to be based on the highway design speed, grade of the deceleration lane, and the design speed of the controlling exit ramp curve. Many state highway officials have supplemented the requirements for deceleration lanes to include the design elements of lane width, storage, tapering, and other criteria developed from local planning requirements and forensics done on exit ramp accidents. As the AASHTO recommendations are also based on the deceleration characteristics of automobiles, many state and local highway departments also review proposed designs to ensure large vehicle traffic is taken into account.
