Questions and Answers about Vehicle Size and Weight

23 CFR 658.11 Additions, deletions, exceptions and restrictions (to NN)

May non-Interstate System designated routes be removed from the National Network?
May Interstate System highway segments be removed from the Interstate System?
May States impose reasonable restrictions on the use of Interstate System routes without authority from the FHWA?
May States restrict use of the non-Interstate System by vehicles authorized to operate thereon under Federal law and regulations, without FHWA approval?
May States restrict the hours that vehicles subject to Federal size limits may use the NN?
Must traffic lanes on the NN be 12 feet wide?
When the National Network (NN) was designated, some States included all Federal-aid primary highways on it without a specific designation. Are they part of the designated network?
May States restrict trucks to specific lanes on multi-lane highways?

23 CFR 658.11 Additions, deletions, exceptions and restrictions (to NN)

May non-Interstate System designated routes be removed from the National Network?

Yes. See 23 CFR 658.11(c), subject to approval by the FHWA.

May Interstate System highway segments be removed from the Interstate System?

Yes. See 23 CFR 658.11(d), subject to approval by the FHWA.

May States impose reasonable restrictions on the use of Interstate System routes without authority from the FHWA?

Only when they are related to specific travel lanes on multi-lane highways, construction zones, adverse weather conditions, or structural or clearance deficiencies. See 23 CFR 658.11(d)(4).

May States restrict use of the non-Interstate System by vehicles authorized to operate thereon under Federal law and regulations, without FHWA approval?

Yes, on specific travel lanes of multi-lane highways, restrictions related to construction zones, seasonal operations, adverse weather conditions and structural or clearance deficiencies [See 23 CFR 658.11(g)].

May States restrict the hours that vehicles subject to Federal size limits may use the NN?

Yes. See 23 CFR 658.11(g)(2), subject to approval by the FHWA.

Must traffic lanes on the NN be 12 feet wide?

No. A traffic lane on the NN must be "designed to be a width of 12 feet or more or otherwise consistent with highway safety." This was provided by the Tandem Truck Safety Act of 1984 in order to resolve the issue of whether traffic lanes on the NN had to be at least 12 feet wide. See also 23 CFR 658.9(b)(5).

When the National Network (NN) was designated, some States included all Federal-aid primary highways on it without a specific designation. Are they part of the designated network?

Yes. The States' inclusion of them as part of the NN was an automatic designation.

May States restrict trucks to specific lanes on multi-lane highways?

Yes. There are no Federal traffic laws that require all highway lanes to be available to all types of commercial motor vehicles.