Criteria for Balanced Geometric Design of Two-Lane Rural Highways

Numbers in parentheses refer to sources listed in the Bibliography© ease with which traffic traverses a highway location with certain geometric features,, To solve the preceding equation for real values representing the actual conditions encountered on two-lane highways located in rural areas, a multiple linear regression equation was evaluated for estimating mean approach speeds and speed reductions .The follovnLng statistical model was developed from the multivariate analysis of traffic flow on two-lane, rural highways: 2. S -39.34 + 0o0267 Xj, Ool396 % -0o8125 X3 -0.1126 X4 + 0.0007 X5 * 0.6444 *6 -0«5451 Xy -0.0082 Xg where S » mean spot speed -mph, X-j_out-of-state passenger cars in traffic streampercent, Xq » truck combinations (tractor with one or more trailers) in traffic streampercent, X3 » degree of curvedeg, X^gradientpercent, Xc minimum stopping sight distanceft, X^-lane widthft, Xjr » number of commercial roadside establishments, such as restaurants, service stations, motels, taverns, etc., per mile (counted on both sides of the roadway for one-half mile in advance of and one-half mile beyond the speed site)no.per all*, and Xg « total traffic volume -vph.The coefficient of multiple correlation was 0.788 for this investigation and was significant at the 5-percent level.The precision of this