Interregional highway

“ To connect all communities classified as urban would require inclusion in the system of a large part of the Nation’s 3,000,000-mile rural road system. Such a system would serve a very large part of the total highway traffic, but its average intensity of usage would be low by reason of the inclusion of much lightly traveled mileage. Obviously, it would be a much more extensive system than any that could properly be described as a major interregional system. ”

“ But the common impression that provision of such routes would constitute invariably a complete, or even a substantially adequate, solution of the highway problem at cities is not well-founded. It is a fallacious conception of the need for adequate accommodation of the traffic moving over the rural highways. From the standpoint of the cities it fails as a solution of the most serious aspects of the problem. ”

“ As important as the interconnection of cities is, however, ideal directness of connection between the largest centers was not attempted, All highway traffic is a composition of long-range and short-range movement, and the highway planning surveys have shown that the latter is the predominant element on all roads. Normally, for example, about 85 percent of all trips are for less than 20 miles, and only about 5 percent for more than 50 miles. ”

“ Where traffic on the rural routes is heavy and, in the environs of cities, where it is desirable to discourage undue extension of road-bordering city growth, prohibition of access to the highway from abutting land, controlled access at specified points, and the closure or grade separation of all intersecting highways are essential. ”

“ Where they can be overcome, the resulting development may be considered by many, more pleasing to the eye and more consonant with a gracious improvement of the urban environment than any other solution of the express-highway problem. Wholly satisfactory design will usually require condemnation of a block-wide strip of property through the city, retaining the existing surface streets at the two ends of the block as local service ways.
PlateVII.—A grade crossing on a four-lane rural section of thee interregional system as it would be designed in conformity with the standards proposed. ”

“ If engineering principles require a certain monotony of smoothness and attention-lulling security in the roadway design, the appropriate application of landscaping principles can relieve the monotony and promote the safety of traffic by reawakening the interest and attention of drivers.
The interregional highways, in their rural sections especially, will serve a traffic composed in large degree of vehicles driven in the pursuit of pleasure or recreation. Sound landscape design will increase the pleasure and relieve the strain of all journeys. ”

“ All ramps and connections shall provide either within their own length or within such length in combination with a section of the parallel service street or way, sufficient storage space for traffic leaving the interregional highway so that such traffic, if temporarily blocked at the intersecting street, will not back up onto the interregional highway. ”

“ These additional data show clearly that, for truck traffic at least, the percentage of the main-highway movement originating in or destined to cities, rises with the increasing range of movement. For the seven States and regions represented in the table, cities are involved as the origin or destination or both in 87.0 percent of the intrastate or short-range movement, 95.5 percent of the interstate or longer range movement, and 96.7 percent of the transstate traffic, or traffic of longest range. ”

“ Where separation of grades at highway intersections is not feasible, and at all points where vehicles may be expected to cross, enter, or leave the interregional highway, the design shall be such as to insure a high degree of safety in crossing, entering or leaving it, without installation of traffic control signals, which shall in no case be employed. ”

“ It is highly important that this force be so applied as to promote a desirable urban development. If designed to do this, the new facilities will speed such a development and grow in usefulness with the passage of time. Unwise location of the interregional routes might not be sufficiently powerful to prevent a logical future city development, but would be powerful enough to retard or unreasonably distort such development. The interregional highways must be designed for long life. An unwise location would diminish their usefulness as time passes. ”

“ Roads carrying less than an average of 1,000 vehicles per day average 20 feet in surface width, or 4 feet less than the width recommended for interregional highways of such traffic volume. The choice of surface type for these roads is generally consistent with the traffic served. The frequencies of occurrence of sharp curves, steep grades, and consequent restricted sight distances as a group average less for these most lightly traveled roads than for most of the heavier traffic-volume groups ”

“ Figure 2.—The 26,700-mile system tentatively proposed as an interregional highway system by the Public Roads Administration in the report, Toll Roads and Free Roads.
Figure 3.—The 29,300-mile system investigated by the Public Roads Administration as an interregional system and described in Public Roads, June 1941.
Figure 4.—The 48,300-mile system, consisting of the more important routes of the 78,800-mile system.
Figure 5.—The 78,800-mile system. This is the largest system investigated by the Committee. ”

“ Unlimited access to the existing main highways has undoubtedly encouraged the outward extension of settlement along them. Per contra, the denial of access to the new arterial highways for a substantial outward distance beyond any desired points on these highways would probably discourage the creeping of settlement along them much beyond the selected points, and this is endorsed by the committee in principle. ”

“ The character of the interregional routes as main collectors of through traffic justifies the granting of preferential right-of-way to traffic moving on them over all crossing and entering traffic everywhere, throughout the system. A proper facilitation of the express traffic with due regard for safety and economy requires, moreover, a reduction of the number of access and crossing points to a practicable minimum. ”

“ At no greater expense one location will provide frequent opportunities for distant vistas of natural charm that are unobtainable in an alternate location. For such enduring investments as the interregional routes there should be no sparing of whatever thought and care may be necessary to place these roads in locations of utmost fitness from every point of view, and this includes the fullest practicable development of scenic possibilities, consistent with the primary requirements of traffic service. ”

“ Among the more lightly traveled of existing highways approximating the location of sections of the system, substantial conformity to the less exacting standards Proposed for such sections of the system is more common. But of these more lightly traveled highways, even, a large mileage cannot be regarded as an acceptable addition to the system without major improvement—improvement which again involves the provision of features of free traffic flow to a greater extent than the provision of adequate road surfaces. ”

“ The volume of highway-freight movements in the future may be expected to be greatest on highways joining the centers of greatest industrial activity. Such highways should be incorporated, as far as possible, in the interregional system.
Figure 7.—The recommended interregional system in relation to cities of various degrees of manufacturing importance, as indicated by the value added by manufacture in each city, as reported by the Bureau of the Census. ”

“ Generally, such routes can be so located as to serve both as arteries for the conveyance of through traffic around the city between various approach highways and as distribution routes for the movement of traffic with local origins and destinations to and from the various quarters of the city. The pattern of such routes will depend upon the topography and plan of each particular city. At most relatively large cities the need will be for routes completely encircling the city. ”

“ Within a block-wide right-of-way the separate roadways may be constructed at different levels in adaptation to an existing transverse slope. The grades of both roadways may be gracefully rolled, dipping to pass under bridges at the crossing streets and rising between to approximate the level of the existing streets which form the local service ways. As they rise and fall the separate roadways may be caused to diverge and converge in alinement, thus varying the width of the median strip. ”

“ That such an improvement of these main arterial roads of the Nation may proceed consistently in all parts of the country, that all may agree upon the particular roads comprising the national routes in all regions and in all States, and that preparations may now be made for beginning the systematic improvement of these roads in the first post-war years—these are the first reasons indicating the necessity for immediate designation of an interregional system. ”

“ The effort to crowd an elevated highway into the narrow space generally afforded by existing surface streets will usually result in unsatisfactory design of the express route and impairment of the utility of the surface street for local service. Generally, it will also cause serious damage to abutting property. To avoid these undesirable consequences it will usually be necessary to acquire a right-of-way wider than can be found within the limits of an existing street. ”

“ All rural sections shall provide a sufficient number of traffic lanes and other facilities so that at no time, except during infrequent peak hours, will it be necessary because of the interference of other vehicles to reduce the average running speed to less than 50 miles per hour. All two-lane rural sections, on which the sight distance provided will not permit safe passing at the above design speed for passenger vehicles, shall be appropriately and conspicuously marked as no-passing zones or as zones in which passing is unsafe. ”

“ 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. ”