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44 RIGHTS-OF-WAY

In general, the design provides a right-of-way width of 300 feet in rural areas and 160 feet in suburban areas. These are in the nature of minimum widths. In rural areas it is expected that they may be exceeded where (1) land values are very low; (2) it may be less expensive to acquire extra land to avoid the cost of constructing grade-separation structures for roads to connect private property divided by the road; or (3) where additional land is needed for some special construction or border control. In suburban areas the minimum width may be exceeded where (1) the additional land is required to allow for expected future growth or to insure effective control of the road; (2) it may be economically feasible to purchase parcels of real estate in their entirety instead of paying damages for areas left isolated by the construction of the road; or (3) it may be less expensive to acquire additional land and so to avoid costly construction, such as retaining walls. In rare instances it may be advisable to restrict the right-of-way to less than the minimum widths mentioned to avoid the purchase of very expensive or important land or buildings, even though the result may be an apparently excessive construction cost; but in no case should this be done at a sacrifice of the minimum standards of design.

CURVATURE AND GRADES It was the purpose to design the selected routes for use at a normal maximum speed of 70 miles per hour. Consistent with this purpose, the normal standards of curvature and gradient were set at maxima of 3° for curves and 3 percent for grades. Jn applying these standards, however, it was necessary to make some concession to topography to avoid costs clearly exceeding the benefits to be gained by adherence. In rugged mountainous terrain an effort was made to keep within maxima of 4° curvature and 4-percent gradient, and this was found possible at reasonable cost except on four sections having and aggregate length of 153.8 miles. For these four sections alternate locations were made, one conforming to the 4° curvature and 4-percent grade requirement, and one permitting curves of 6° and grades of 6 percent.

The estimated cost of constructing the 153.8 miles to the lower standard is $26,107,000. Built to the higher standard these lines would aggregate 172.4 miles in length and their cost would be $42,124,600. It is concluded that the advantage to be gained by building to the higher standard would not justify the additional 18.6 miles of travel and the increased construction cost of $16,017,600.

The sections involved and the estimated lengths and costs of each are as follows: