TM 5-822-2/AFM 88-7, Chap. 5
(2) Lane width.
geometric design criteria for on-street parking lanes are
(a) Traffic lanes. Safety, driver comfort,
given in table 1-2. Justification for all such on-street
parking facilities will be furnished to Headquarters,
and capacity are directly affected by lane width, and
Department of the Army (DAEN-ECE-G) Washington,
proper consideration must be given to each of these
DC 20314-1000, or the appropriate Air Force major
items. The width of a traffic lane is dependent upon the
command.
width and operational characteristics of vehicles, speed,
(3) Curbs.
composition, and volume of the traffic, and the location
(a) Policy. In built-up areas, curbs,
of barrier curbs. The number and width of traffic lanes
combination curbs and gutters, and paved gutters with
shown in tables 1-1 and 1-2 are the minimum considered
attendant underground storm drainage systems will be
adequate to accommodate the indicated design hourly
provided along streets and in open storage areas when
volume when the traffic is composed principally of
required to aid in the collection and disposal of surface
wheeled vehicles whose overall widths are 8.5 feet or
runoff including snowmelt, to control erosion, to confine
less. Wider traffic lanes are required when the traffic is
traffic, or as required in the extension of existing similar
composed of a significant percentage of vehicles whose
facilities. In open areas, combination curbs and gutters
overall widths are greater than 8.5 feet. Where class A,
will not be provided along roads except where necessary
B, C, or D roads or streets are being planned to
on steep grades to control drainage and prevent erosion
accommodate traffic of the composition "T = 20 percent"
of shoulders and fill slopes. Where such facilities are
or greater, which includes vehicles greater in overall
required, they should be located outside the edges of
width than 8.5 feet, the traffic lanes of these roads or
traffic lanes and should be either of the mountable type
streets should be increased in accordance with the
with suitable outlets and attendant drainpipes or paved
following formula:
gutters with shallow channels extending across the road
wt + (wv 8.5)
(eq 3-1)
shoulders and down the fill slopes. Inverts and sides of
W
=
roadside ditches will be paved where necessary to
where
control erosion. Criteria and standards for curbs and
W
=
width of widened traffic lane, feet
gutters for Department of the Air Force installations are
=
width of traffic lane shown in table 1-1
wt
specified in AFM 88-15, chapter 15.
(b) Classification and types. Curbs are
or 1-2, feet
=
average width of the 10 most
wv
classified as barrier or mountable according to their
representative
excessive-width
intended use. Barrier curbs are designed to prevent or
vehicles expected in the traffic, feet
at least discourage vehicles from running off the
pavement, and therefore have a steeply sloping face at
The traffic lane of class E roads and streets planned to
least 6 inches high. Mountable curbs are designed to
accommodate traffic of the composition "T = 30 percent"
allow a vehicle to pass over the curb without damage to
or greater should be widened as indicated above for
the vehicle, and have a flat sloping face 3 or 4 inches
class A, B, C, or D roads and streets. No adjustment will
high. For construction purposes, curbs are usually
be made for excessive-width vehicles on class F roads
designated as "combined curb and gutter" and "integral
or streets. Such adjustments are not economical for the
curb and gutter." For Army installations, curbs are
low volumes associated with class F roads. Additional
divided into four types for convenience of reference: type
widening of traffic lanes is required on horizontal curves
I is a combined gutter section and barrier curb; type II is
as discussed in 3-3d.(2) below.
a combined gutter section and mountable curb; type III is
(b) Parking lanes. It is the policy of the
a combined gutter section and offset barrier curb; and
type IV is a barrier curb integral with pavement slab.
Department of Defense (DOD 4270.1-M) to provide off-
Standard details for each of these four types of curbs are
street parking facilities at military installations in lieu of
shown in CE Standard Drawing No. 40-17-02. These
wider streets required for on-street parking. However, at
details apply to both rigid and flexible pavements. The
many existing installations it may be necessary to
compacted subgrade. subbase, and base course layers
provide on-street parking spaces in local areas by
should extend under the curb and for a distance equal to
widening existing streets due to the lack of space for off-
the base course thickness beyond the backface of the
street parking facilities. Normally, such parking will not
curb
be provided on class A, B, or C existing streets, but in
those instances where the provision of on-street parking
on existing class B and C streets cannot be avoided,
3-9
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