TM 5-822-2/AFM 88-7, Chap. 5
have no relation to warrants for signalization, nor are
underground utilities should be located beneath any part
they indicative of whether or not signalization should be
of the pavement, except where crossings are required.
used. Warrants for traffic control signals are given in the
Where these underground utilities must cross beneath
Federal Highway Administration Manual on Uniform
highways, they should be so designed and constructed
Traffic Control Devices for Streets and Highways.
as to minimize future repairs and consequent
(5) Intersection curves.
interference with traffic. Obstructions including signs and
(a) Minimum edge of pavement design.
poles for overhead utilities shall be located outside the
limits of usable shoulder on highways designed without
Where it is necessary to provide minimum space for
barrier curbs. Where practicable, highways designed
turning vehicles at unsignalized at-grade intersections,
with barrier curbs should have the desirable lateral
the AASHTO designs should be used. The minimum
clearances to obstructions shown in tables 1-1 and 1-2,
radius for edge of pavement design on street
except that fire hydrant clearances shall be in
intersections is 30 feet, which is required for passenger
accordance with TM 5-813-5 on Army installations.
(P) cars on 90degree turns. A larger radius should be
Generally, utility poles should not be located in medians
used if any truck traffic is expected or turning speeds
on divided highways.
greater than 10 miles per hour are anticipated. The
minimum radius on road intersections is 50 feet.
highway and a structure which entail the undercrossing
or overcrossing of a railroad are substantially the same
radii are normally used at plain unsignalized intersections
as for a highway grade separation without ramps. The
to reduce intersection area and minimize conflict
geometrics of a highway at an at-grade crossing are
between pedestrians and vehicles. The curb design
discussed in American Railway Engineering Association
should fit the minimum turning path of the critical design
(AREA) Manual for Railroad Engineering. The AREA
vehicle expected in the traffic. As shown in AASHTO
recommends the practice which should be used at at-
urban literature, minimum curb radii vary with design
grade intersections of highways and railroads relative to
vehicle, angle of turn, number of traffic lanes, whether
signs, signals, gates, etc.
parking is permitted, and traffic composition. Generally,
(4) Pavement markings. Marking should be
the minimum curb radii to be used on intersection curves
provided on paved surfaces as a safety measure and to
may be determined on the basis of the following
increase orderly traffic flow. Markings should be in
information: Curb radii of 15 to 25 feet are adequate for
accordance with the Manual on Uniform Traffic Control
P design vehicles and should be used on classes D, E,
Devices for Streets and Highways.
and F cross streets where practically no SU, WB40,
WB50, and WB60 (truck) design vehicles are expected
or at major intersections where parking is permitted on
3-4.
Walks.
both intersecting streets. Radii of 25 feet should be
a. Need. At certain isolated locations in open
provided on all new construction and on reconstruction
areas, the need for walks may be as great as in built-up
where space is available. Curb radii of 30 feet or more
areas, especially in the vicinity of shopping centers,
should be provided at all major highway intersections to
schools, industrial plants, and at other similar locations.
accommodate an occasional truck in the traffic. Radii of
Minimum walk requirements should be determined on
40 feet or more, preferably three-centered compound
the basis of need, irrespective of type of area, as a part
curves to fit the path of the critical design vehicle
of the master plan development.
expected in the traffic, should be provided where SU,
b. Policy. Smooth, hard-surface walks should be
WB40, WB50, and WB60 design vehicles turn
provided to accommodate pedestrian traffic. Walks will
repeatedly.
be provided in accordance with American National
g. Miscellaneous.
Standard Institute (ANSI) Standard A117.1.
(1) Signing.
Signs should conform with
c. Geometric design.
Safety and volume of
standards given in AASHTO's Manual of Uniform Traffic
pedestrian traffic are the primary controls for geometric
Control Devices and Standard Specifications for
design of walks. The traffic volume used for design
Structural Support for Highway Signs, Luminaries, and
should be the average of the maximum hour for each
Traffic Signals.
day for a year. However,
water, and sewer lines will normally be located within the
right-of-way of highways. In order to prevent utility
maintenance from interfering with highway traffic, no
3-22
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