interstate design standard
interstate design standard
(OP)
I know interstates have to be designed to AASHTO standards but what about ramps at interchanges? Is there a grey area along the ramp where the standard changes from AASHTO to the state design manual?





RE: interstate design standard
All highways, including Interstates, are done to the local State DOT standards and/or Turnpike/Toll Highway Authority. Many of these standards incorporate AASHTO by reference, but note exceptions to AASHTO in their own design publications.
Occaisionally, you will be working with two state jurisdictions, but there is usually a clearly delineated scope as to which standard applies.
Contact the agencies for copies of their design guidance. Many are available online for download. Some jurisdictions have more complete and comprehensive guidance published than others.
Jeff