highway and, if deemed feasible, at the intersecting highway also shall be designed as one-way roads separated by suitable channelizing islands. Entrances and exits shall be located at sufficient distances from any grade-separating structure to provide sight distances adequate for safety under the conditions of vehicular speed to be anticipated.
All ramps and connections shall be designed to enable vehicles to leave and enter the through-traffic lanes of each highway at 0.7 of its design speed, except where “stop” control is necessary. The maximum curvature of ramps and connections shall preferably not exceed 45°, and under no conditions shall exceed 70°. All curves shall be eased by transition or compounding.
Width of pavements and shoulders and side slopes.—All ramps and connections shall be made as wide and side slopes shall be made as flat as hereinbefore recommended for rural sections of the system. Shoulders may be omitted under appropriate conditions; but, if provided, shall conform to the standards recommended for rural sections of the system.
Added space for turning maneuvers.—Added space for turning maneuvers shall be provided, and shall be designed as hereinbefore recommended for rural sections of the system.
Gradients on ramps.—The gradient on ramps shall not exceed 6 percent on upgrades and 8 percent on downgrades.
Sight distance at ramps and connections.—On all ramps and connections the combination of grade, vertical curves, alinement, and clearances of lateral and corner obstructions to vision shall be such as to provide a sight distance along such ramps and connections and from their terminal junctions along the interregional highway and intersecting road or street consistent with the probable speeds of vehicle operation.
Access for busses.—Bus stops shall be prohibited on all urban sections of the interregional system. Access connections for bus stops off the interregional highway shall be designed to the same standards as other access connections.
V. Tunnels.
Tunnels on urban sections of the interregional system shall accommodate the same number and width of traffic lanes as are provided on the street or highway approaching the tunnel and shall conform to all recommendations hereinbefore made for tunnels on rural sections of the system.
VI. Pedestrian and recreational facilities.
On urban sections of the system, pedestrian usa of road surfaces and pavements shall be prohibited.
Pedestrian use of shoulders or standing areas shall be prohibited wherever feasible. Where walks are provided in these areas, they shall be separated from the edge of the pavement for vehicles by a curb and a strip at least 6 feet wide.
Where median strip or border areas of the interregional highway are of dimensions sufficient to permit their safe use for pedestrian purposes or for recreational facilities, such as rest and comfort facilities and playgrounds for both road users and nearby residents, their use for such purposes shall be encouraged either by the provision of these facilities or the assignment of space for their future development
