highway and airport engineering
TRANSCRIPT
04/11/23 Introduction 1
GEOMETRIC DESIGN OF HIGHWAYS
ByDr. MANAL ABD ALLA
Chapter1Introduction
04/11/23 Basic Design Control 2
Definitions:
Geometric design: pertains to the design of the visible features of the highway
Design Controls: They are the factors affecting the different geometric design elements of highways.
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3
GEOMETRIC DESIGN COURSE CONTAINS:
Chapter 1:Introduction.Chapter 2:Basic Design
Control.Chapter 3:Sight Distance.Chapter 4:Horizontal
Alignment.Chapter 5:Vertical Alignment.Chapter 6:Cross-sectional
elements.Chapter 7:Highway
Intersections.
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Chapter 2Basic Design
Control
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Basic Design Control
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Primary Control
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1-Highway Classification
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Primary Control( Cont.)
The nature of the surrounding topography and land use may govern in many cases the choice of best alternative of highway location.
It also governs highway slopes, drainage, speed, …
2-Topography
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Primary Control (cont.)
Traffic VolumeAverage Daily Traffic (ADT), AWDT,AMDT, AADT. Design Hourly Volume (DHV) = k × ADT
Rural: K=11-20%, Urban: K=7:18% Traffic Composition
Percent of non passenger cars (T)
Vehicle Type Equivalent Factor
PCBusSUT
TrailerHand Driver
Car
12
2.53.56
3-Traffic Data: It must include volume, Composition, and projection
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Traffic Projection Normal Growth, Generated, Attracted, Developed.
Primary Control (cont.)
Current
Developed GeneratedAttracted
N.Growth
Total
Future ADT = Current ADT (1+ TPF)
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1-Speed(Distance over time……..mph,kph,
ft/sec.)Running speed: Distance / overall time.Operating speed: The highest overall speed
in such a way it is not greater than the design speed.
Design speed: The speed selected for design of highway elements.
- It is the max. safe speed- It is the speed that at least 95% of
the drivers use speed less than or equal to it.
Dependent Control
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Dependent Control (cont.)
2-Design Vehicle Is that vehicle selected to represent all vehicles on the highway
Types: - Passenger Car (PC)
- Single Unit Truck (SUT)
- Bus
- Semitrailer Combination (WB-40)
- Semitrailer Combination (WB-50)
- Semitrailer Fulltrailer (WB-60)
Single Unit Truck (SUT) is the type of the vehicle considered according to Egyptian Specifications
Dependent Control (cont.)
PC SUT BUS WB-40 WB-50 WB-60
Min.Turning
7.3 12.8 12.8 12.2 13.7 13.7
Min.Inside
4.7 8.7 7.1 6.1 6.0 6.9
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2.6 m
9.1m
13.4 m Max.
8.7 m Min.
12.8 m Turning
SUT
Turning Radii
Design Vehicle
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Design Designation
They are the major controls for which a given highway is designed
Design Year ( Ex. 20 Years Ahead) Current ADT Future ADT DHV Directional Distribution (D) % Truck (T) Design Speed (V) Control of Access ( None, Partial, or Full) Design Level of Service (A, B, C, D, or E)