This chapter presents guidance on the application of geometric design criteria to facilities functionally classified as local roads and streets.

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INTRODUCTION
This chapter presents guidance on the application
of geometric design criteria to facilities
functionally classified as local roads and
streets. Local roads and streets constitute a
high proportion of the roadway mileage in the
United States. They provide access to farms,
residences, businesses or other abutting
properties. Traffic volume greater than 400
veh/day is one of the design criteria for design
of local roads and streets. Roads less than 400
veh.//day are not applicable to the design
criteria in this chapter. AASHTO is working on
the design of these types of roads. This chapter
discusses three types of roadways Local Rural
Roads, Local Urban Streets, and Special Purpose
Roads
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LOCAL RURAL ROADS
Constituted by the majority of two lane local
roads Design ADT 20 years after the date
of completion of construction or 20 years
from the current year Design Speed see
Exhibit 5-2 Sight Distance see Exhibit 5-2 for
SSD see Exhibit 5-3 for PSD Grades Maximum
grade see Exhibit 5-4 Minimum grade see P242.
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LOCAL RURAL ROADS
Alignment consistent and smooth two-lane
alignment Cross Slope 1.5 2 for high-type
pavement 2-6 for low-type pavement see
Exhibit 5-5 Superelevation e no more than 12
generally e no more than 8 at snow and ice
conditions Structure Bridges to remain
Standard Specifications for Highway Bridges In
place see Exhibit 5-6 and Exhibit 5-7 Vertical
Clearance at least 4.3 m
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LOCAL RURAL ROADS
ROW Width Should be acquired to accommodate
construction, adequate drainage, and proper
maintenance of a highway Foreslope Not
steeper than 1V2 H The ditch bottom and
slopes should be rounded. The backslope
should not exceed the maximum required for
stability. H. Clearance to Obstructions 2-3 m
clearance from the ETW Curbs see curbs in
the Local Urban Streets Intersection Design no
intersection on a short-crest vertical curve or
on a sharp horizontal curve. More on Chapter
9 on Intersections Design
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LOCAL URBAN STREETS
A local urban street is a public roadway for
vehicular travel including public transit and
refers to and includes the entire area within the
ROW. It also serves pedestrians and bike traffic
and accommodate public utility facilities in the
ROW. Design ADT 2 or 4 lanes f(traffic
volume) 10 or 20 years after the date of
completion of construction Design Speed 30 50
km/h. Not a controlling factor in design. In the
typical street grid, the closely intersections
limit travel speeds, making the design speed
less important. Sight Distance 30 60 m
depending on design speed (see Exhibit
3-1) Grades lt 15 General 8 for commercial
and industrial areas desirable 0.3 min for
streets with outer curbs
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LOCAL URBAN STREETS
Alignment fit with the existing topography to
minimize the needs for cuts or fills
discourage through traffic Min. Radius of
a horizontal curve 30 m cannot be less than
25 m for a 30 km/h design speed Cross Slope 1.5
2 for high-type pavement 2-6 for low type
pavement Superelevation Usually superelevation
is not needed in residential and commercial
areas. When superelevation is used, emax
4 Number of Lanes At least one unobstructed
moving lane must be ensured even where parking
occur on both sides. Roadway Width 3.0 3.6
m/lane
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LOCAL URBAN STREETS
Parking Lanes A parallel parking lane a min. 2.1
m wide should be provided on one or two sides
in residential areas. 2.4 m for commercial and
industrial areas. Medians Median openings should
be located with adequate sight distance. Shape
and length of the median openings f(median
width, and vehicle type to be served) Curbs Stre
ets normally are designed with curbs. The curbs
are 100 mm to 150 mm high. Vertical curbs with
150 mm high or more should be offset at least
0.3 m. Drainage gutter min. grade
0.3. Surface water are collected by curbs,
gutters, and ditches and conveyed to a
drainage system Cul-De-Sac and Turnaround Min.
outside radius 10 m 15 m. See Exhibit 5-8.
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LOCAL URBAN STREETS
Alleys Alleys provide access to the side or rear
of individual land parcels. They are a narrow
ROW and range from 5-6 m (width) in
residential areas and up to 10 m in industrial
areas Sidewalks Desirably on both sides of
streets. Min. width is 1.2 m. Sidewalk
Curb Ramps See AASHTO Guidelines for the
Planning, Design, and Operation of Pedestrian
Facilities. Driveways Driveway returns should
not be less than 1 m in radius. Roadway
Widths For Bridges see Exhibit 5-6 H. Clearance
to Obstructions A min. 0.5 m should be provided
between the curb face and obstructions.
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LOCAL URBAN STREETS
Vertical Clearance at least 4.3 m Border
Area A border area should be provided along
street for the safety of motorists and
pedestrians as well as for aesthetic reasons.
It is the area between the roadway and
ROW. 1.5 m to 3.0 or wider ROW Width varies
in order to accommodate planned
roadway. Intersection Designs see Chapter
9 Street and Roadway see Exhibit 5-11 Lighting
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SPECIAL PURPOSE ROADS
Special purpose roads include recreational roads,
resource recovery roads, and local service
roads. Recreational Roads Criteria are to
protect and enhance the existing aesthetic,
ecological, environmental, and cultural
amenities. Recreational roads involve three
types of roads primary access roads,
circulation roads, and area roads. See Exhibit
5-12. Design Speed 60 km/h primary access
road 50 km/h circulation roads 40 km//h
area roads Design Vehicle Motor homes,
vehicles with trailers, PU
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SPECIAL PURPOSE ROADS
Recreational Roads Sight Distance See
Chapter 3 SSD should be measure with an eye
height of 1080 mm and an object height of
1300 mm. The SSD is doubled for a two-way
single lane road. See Exhibit 5-13. PSD see
Exhibit 5-14. Grades see Exhibit 5-15 for max
grade Vertical Alignment see Exhibit 5-1. SSD
doubled on two-way, one lane
road. Horizontal Alignment emax 6 no
SE on roads with design speed of 30 km/h f
different in Exhibit 5-16.
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SPECIAL PURPOSE ROADS
Recreational Roads Number of Lanes Two-way
one lane for lt 100 veh/h turnouts at max.
interval of 300 m should be provided when
two-way and one lane is considered. Turnouts
should be gt3 m wide, 15 m long and a taper of
8 m at two ends. See Exhibit 5-17 Cross
Section See Exhibit 5-18 cross slope for
local rural roads are applicable Clear
Recovery Zone 3 m or more recovery
area Roadside Slope 1v4 H Roadside
Barrier see AASHTO Roadside Design Guide
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SPECIAL PURPOSE ROADS
Resource Recovery Roads Mining and logging
roads are the resource recovery roads. Criteria
are same as those for recreational
roads. SE emax 6 Grades considering the
requirements of large loaded vehicles Design
Speed See Exhibit 5-19 Local Service
Roads Those serving isolated areas that have
little or no potential for further development.
Criteria are same as those for recreational roads.