PC*MILER State + National Network routing favors using the U.S. Federally designated National Network (primary Interstates with reasonable entry/egress points up to 1 mile off the Interstate), combined with a preference to favor using the state-designated extensions to the Federal National Network (additional highways and supporting roads that can be any distance off the Interstate, as determined by the individual states).

State + National Network routing can be selected using the Road Network route option under Routing Preferences, either as part of a route profile or in the Route Options dialog for an individual route

What is the National Network?

The National Network is a U.S. government-designated system of highways originally established by the Surface Transportation Assistance Act of 1982 (STAA). This routing option is based on the federally-designated National Network system updated in the April, 1992 Code of Federal Regulations, Part 658, Appendix A. The National Network includes the Interstate System (several minor segments are not included), and many selected U.S. and state highways. Highways continue to be added to the National Network by federal and state governments.

PC*MILER National Network routing represents distances and driving routes which are most reasonable and legal for the larger trucks authorized by the Surface Transportation Assistance Act of 1982.

National Network routing stays on the National Network to the maximum extent possible.  Given that many areas are not directly served by the National Network, the origin and stop-offs of your route may not be on the National Network. In these cases PC*MILER will take the shortest reasonable path from the origin and stop-offs to the Network. Detailed Route Reports (driving directions) for PC*MILER National Network routes provide a warning wherever the route is forced to use a non-conforming link. These road segments should be checked before traveling.

National Network mileage tends to be higher than Shortest or Practical mileage.

TIP: PC*MILER’s suggested National Network routings are based on official highway maps, the Code of Federal Regulations, and information provided by state governments. It is provided without a warranty of any kind. The user assumes full responsibility for any delay, expense, loss, or damage which may occur as a result of its use.

53' Trailer or Twins Routing 

The regulations that govern the routing of trucks in North America are a function of weight, height, number of axles, distance between axles, number of trailers, and commodity. These regulations take two principal forms: restrictions and designations. In the case of designations, trucks may deviate from the designated road network, on any road that is not otherwise restricted, to access points of loading, unloading and services. 

Under the 1982 U.S. federal law known as the STAA, the most important distinction in truck designations is between 96'' wide, 48' long trailers on the one hand and 102'' wide, 53' long trailers (and twin 28' long trailers) on the other hand.  When the State + National Network routing option is used in PC*MILER, or when a width of greater than 96'' or a length greater than 48' is entered into PC*MILER as the vehicle size, PC*MILER’s routing algorithm switches to favoring roads designated by the states for “oversize” trucks (over 96'' wide or 48' long).


In PC*MILER, the routing designations for the following equipment types are included in the State + National Network routing category:

  • double trailers no more than 28' long and 102'' wide;
  • semi-trailers longer than 48' or wider than 96'', but no longer than 53' and no wider than 102''.

Detailed Route and Driver’s reports for State + National Network routes warn that a road is “Not Designated” if that road is necessary to reach an origin, destination or stop-off outside of the maximum access distance for that state. In this case the circle that represents the stop on that link in the route window will turn solid red. If the cursor hovers over it a tooltip will tell you what type of warning it is. 

If such a warning appears, then a legal route for 53' equipment is either not possible under current state designations or would be so circuitous that you should either consider assigning smaller equipment or petitioning the state to designate a more direct access route. Users should check the legal requirements on these roads because they vary; for example, delivery may be legal, but stopping for food or services may not be.

“Not Designated” Warning in a Route Window and Detailed Route Report

If the Designated Truck Routes layer in the Map Features dialog is turned on, the PC*MILER map will display the 53-foot designated network with a light blue underlay when the map scale is approximately 1'' equals 8 miles or less. This underlay is hidden by default. (Note: If you have the Hazmat add-on installed and the Hazardous Material layer is turned on, you may want to turn it off for a better view of designated truck routes.)