Download - 6 cross section elements ( Transportation and Traffic Engineering Dr. Sheriff El-Badawy )
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Highway Cross Section Elements
• Travel Lanes (Carriageways)
• Shoulders
• Medians
• Roadside Barriers
• Curbs
• Gutters
• Guard Rails
• Sidewalks
• Side (cross) slopes
Principal Elements Marginal Elements
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Typical Cross Section of Rural
Road
Highway Engineering, Tonias, D.
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Typical Cross Section of Rural
Road
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Typical Cross Section of Urban
Road
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Typical Cross Section of Urban
Road
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Travel Lanes
• In general, the number of travel lanes should be based on
the design traffic volume and level of service.
• No. of travels lanes in both directions are usually equal.
• Travel lanes generally range in width from 10 to 13 ft.
(3 to 3.95 m).
• Typically is 12 ft (3.65 m)
• Under extreme circumstances, a width of 9 ft (2.75 m) may
be used.
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Shoulder
• Shoulders usually range in width from 2 ft (0.6 m) for minor
local roads. (6 to 8 ft – 1.8 to 2.44 m- is preferred) to 12 ft
(3.65 m) for major highways.
• Typical cross slope is 3% for paved shoulders and 5% for
unpaved shoulders .
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Medians
• A median is a wide strip of a highway used to separate
traffic traveling in opposite directions.
• Offer a recovery area for errant vehicles
• Provide an area for emergency stopping
• Serve as a safe waiting area for left-turning and U-turning
vehicles
• Decrease the amount of headlight glare
• Allow for expansion to future lanes
• Medians can be Flushed – Depressed- Raised.
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Sharja, UAE
Moscow, Idaho UI Campus
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Cross (Side) Slope
• The slope selected generally depends on the type of
pavement used.
• Typical cross slope of 1.5 to 3% is recommended.
• Cross slopes greater than 2% should be avoided (for
safety).
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
A curb is a raised element that is used, among other things,
to denote the edge of a roadway.
Functions of curbs
• Drainage control
• Roadway edge delineation
• Enhanced appearance
• Right-of-way reduction
• Delineation of pedestrian walkways
• Reduction of maintenance operation
Types of curbs:
Vertical curbs -- discourage vehicles from leaving the roadway,
not desirable on high-speed highways, desirable on urban
roads, and along long walls, tunnels to protect safety walks.
Sloping curbs -- vehicle can cross them readily when required,
used at median edges, to outline channelizing islands, at the
outer edge of the shoulder.
Curbs
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Curbs
• Barrier Curbs• The purpose of a barrier curb is to prevent or limit the possibility of
a vehicle’s leaving the roadway.
• A general rule of thumb is that barrier curbs should not be used
when the design speed is greater than 40 mph.
• Mountable Curbs • A mountable curb offers the advantage that a vehicle can cross it
when necessary.
المنصورة-قسم الهندسة المدنية –معهد مصر العالي للهندسة والتكنولوجيا
Sidewalks
• Sidewalks are an integral part of city roads, sometimes
provided in rural areas.
• In residential areas the sidewalk width varies between
1.2 to 2.4 m.