The grade of the toll road, wherever possible, would be laid above the general level of the surrounding land. Where divided roads are located on slopes, the two sides would be placed at different levels in the interest of economy of construction, additional safety through the reduction of headlight glare, and a more pleasing appearance.
INTERSECTIONS
On the roads as planned there would be no intersections at grade. At no point would a driver encounter another vehicle. crossing his path; and at no point, except at the especially designed accesses, would he encounter another vehicle entering the roadway. Railroad grade crossings would be avoided generally by carrying the highway overhead. In fewer instances the highway would pass beneath the railroad.
All intersecting highways of importance would be carried over or under the proposed roads. Cross roads serving light traffic would be closed and their traffic diverted via existing roads, or roads constructed for the purpose, to the nearest grade-separated intersection. The same considerations would govern in respect to the treatment of intersecting streets in suburban areas. Traffic on unimportant intersecting streets is frequently much greater than on the lesser roads in rural areas. For this reason grade-separation structures would probably be much closer. The construction of parallel streets would not only serve rerouted traffic from unimportant streets but also serve adjacent property cut off by the construction of the proposed road. A typical 4-lane highway in an urban area is shown in plate 30.
At all points where the selected routes intersect, the design would be such that traffic, regardless of direction, would be able to proceed or turn without crossing traffic on either road. All traffic would leave or enter at the right on suitable acceleration and deceleration lanes. The full clover-leaf type of grade-separation structure meets all conditions and requires but one structure. It is more confusing to the driver, however, than some “braided” types of intersection which may require more than one separation structure but which result in more direct access roads.
PRIVATE PROPERTY CROSSINGS AND CATTLE PASSES
Where private property is divided by the construction of the roads use of the land would be restricted to a considerable extent. To minimize the restriction it would be necessary to provide crossing-separation structures to permit passage from one part of the property to the other sufficiently close together and of sufficient size to insure reasonable use of the land as a whole for its intended purpose. In rural areas simple cattle passes will often suffice though sometimes the structures may have to be built large enough to accommodate wagons and motor vehicles. In suburban areas, where the land is subdivided, the structure clearances and load capacities would have to be sufficient for use as a future street. In some cases it may be sufficient to agree to construct a grade separation structure at a future time when the need develops. In other cases, where the value of the land is low, acquisition of the affected land may be the most economical procedure.
