Show when it Is economical to build paved highway one of the most important phases 0 of highway research tins been a series of tests teats for the purpose of establishing how heavy the traffic must be to warrant the paying paving of a highway in commenting recently on tills this subject mr F P IL white president of the american association of state highway IrIg hway officials fici fl als issued the following state ment when the truffle on the flirt dirt road reaches tons per day average then it becomes ti to pave it in other words when the dirt road la Is carrying a traffic equalito equal to cars cara per day it Is economical to pave that road the savings in the operating cost of a vehicle will pay the interest on the bonds we will say that are issued to pay for the roads and will retire those bonds in a period of fifteen years paying the whole bill when the traffic on a gravel road becomes tons per day it then becomes economical to pave that road as it will w III save money that Is the point which up until the present time we did not have data to determine now we can say with a considerable degree of certainty just when it becomes economical to build a higher type road |