Page:Highway Needs of the National Defense.pdf/113

Rh State is a matter to be reckoned with by the highway authorities, if for any reason it appears that highways should be designed to accommo-date vehicles of maximum size and weight either larger or smaller than the existing law allows. Presuming that highways throughout the Nation should be built to standards uniformly adequate in all States, the variety of size and weight laws persisting, highway authorities of many States are unavoidably confronted with the necessity of justifying any decisions they may reach as to road standards that appear inconsistent with the existing State law.

More serious than its effects upon highway design policy, however, is the effect of this variety of State vehicle regulatory laws upon the flow of interstate traffic. When different dimensions and weights are fixed as the largest permissible in each of two States, vehicles that can legally be operated in one can be operated in the other only in violation of law. The difference in the laws becomes a barrier obstructive of a desirable freedom of movement from one State to the other

WARTIME LIMITS

The unfortunate effects of such differences in State laws are never more apparent than in wartime. In an effort to surmount the difficulties presented by the variety of laws existing at the outbreak of World War II, the President early recommended in letters to the Governors of all States that they arrange in some manner to accept in their States, as permissible for the duration of the war, movements of vehicles conforming to a certain few dimensional and weight limits.

These limits, which became known as wartime limits, were either in some manner adopted or tolerated in all States while the war continued.

The limitations thus proposed and accepted were as follows: This hurriedly arranged uniformity of vehicle regulation was far from satisfactory, either as assurance of the unobstructed movement of war traffic or as a measure of highway conservation. The 18,000-pound axle load limit was soundly based upon the prevailing load-supporting capacity of the highways. This accepted, the limit of 30,000 pounds as the maximum gross weight of a two-axle vehicle was inconsistent and unattainable if the axle limit were observed, since to realize the total load permitted would have required an impracticable loading of the front axle. This inconsistency existing, highway haulers of important war shipments might be, and they doubtless were forgiven if they complied with the 30,000-pound gross load limit and violated the axle-load limit.

The limit proposed for the gross load of a three-axle vehicle, at 40,000 pounds, was at least attainable in a vehicle without infringement of the axle-load limit; but both of the gross weight limitations