Is ADT the only criteria for road Class for IDOT?

[GE34]

Fellow Engineers,

Is ADT the only criteria for Road Classification (I.e Class II vs. Class III) in Illinois? Please give me your best engineering judgement because it's critical for me to have the correct assumptions for problem definition.

For example, a two lane (1 lane in each direction)street in a fully developed industrial park has existing bituminous pavement over crushed stone with existing concrete curb and gutter.

The pavement is to be reconstructed and/or overlayed. Currently, there is distressed 4" of Bituminous Concrete overaying approxiamtely 10" +/- 2" of aggregate base course.

A traffic study has counts underneath 2000 ADT and per the Bureau of Design & Environemntal (BDE) Manual, Chapter 54 strictly on its definition--this would be a Class III road. However, a colleague of mine has stated that this is a Class II road based on its used a a fully developed industrial park with with curb and gutter and lots of truck traffic.

The BDE manual defines Class III roads and streets as " Roads and Streets with a structural design traffic between 750 ADT & 2000 ADT."

The BDE manual defines Class II roads and Streets as "Roads and Streets designed as a two-lane facility with Structural design traffic greater than 2000 ADT, and all one-way streets with structural design traffic less than 2000 ADT."

Based on Traffic counts the The projected fututre ADT is approxiamtely between 1000 to 1700. (and would seemingly put this street in a Class III).

So once again, Is ADT the only criteria for Road Classification (I.e Class II vs. Class III) in Illinois?

Thanks for your time.

 

[Ron]

If that is the document that defines your design criteria, then it would appear that you are correct. If the IDOT allows different criteria, then perhaps there are other methods that would apply....call and ask the state design engineer.