Page:Interregional Highways.pdf/127

Rh The group of roads serving traffic between 2,000 and 3,000 vehicles daily, a density for which the recommended standards would require the provision of four traffic lanes in the presence of restricted sight distance, is shown to have, on the average, more numerous restrictions of sight distance than the most lightly traveled sections, and surfaces of the same average width as the most lightly traveled sections.

In the groups carrying average daily traffic between 3,000 and 10,000 vehicles for which divided four-lane pavements are recommended throughout there is some evidence of a beginning of widening, still far from adequate; and even the most heavily traveled sections, carrying traffic in excess of 10,000 vehicles daily, average less than the desirable four-lane width and have these inadequate widths cramped within rights-of-way so narrow as to prohibit the essential widening.

A substantial mileage of the wider roads that account for the greater average widths of sections carrying upward of 3,000 vehicles per day, as shown in figure 33, are surfaced with three-lane and four-lane, undivided pavements, These types of improvement, largely employed as expedient measures in the thirties, have no place among the standards recommended by the Committee for the interregional system. Table 17, however, accounts for 1,364 miles of three-lane and 1,181 miles of undivided four-lane pavements in the total of 3,451 miles of pavement wider than two lanes that existed in 1942 on the highways conforming approximately to the interregional system, and shows that only 906 miles of these roads were then improved with divided four-lane pavements and pavements more than four lanes wide.

It will be observed that four-lane pavements have been provided on a comparatively small mileage where the traffic volume is less than that proposed for general design of that width. Three-lane pavements on other sections serve a traffic greater than that proposed by the Committee as a criterion for four-lane divided design and considerably greater than that served by other sections on which four lanes have been provided.

It will be noted also that some sections of undivided four-lane design serve traffic of greater volume than that for which divided four-lane accommodation has been provided on other roads.

The fact that much of the mileage classified as providing three, four, or more lanes does not actually provide the number of lanes 93800—44—8