Applications of Safe Stopping
Distance
Stopping in response to an event
A driver who encounters an object in the
travel lane must see it in time to react and
stop the vehicle.
Example
A driver travels uphill on a 2 % slope on a
roadway with a design spee
HORIZONTAL CURVES
What They Are And How To Deal With Them
FOR 373
Fall Semester
2
FOR 373
Fall Semester
HORIZONTAL CURVE TERMINOLOGY
Symbol
Terminology
Equation
LC
Long Chord
2R sin 2
R
Radius
OA = OB = OC
L
Length of Curve
L = 0.0174533 R
T
Tangent Dist
VERTICAL CURVE EQUATIONS
STANDARDS
LEGEND EQUATIONS
gt 8: g: : Intersecting gradients in %
A = Algebraic difference in A : (i g») (i g.)
gradients
L 2 Length of vertical curve in stations AL
B.V.C. = Beginning of Vertical Curve h =
8
E.V.C. = End o
ESSENTIALS 0F TRANSPORTATION ENGINEERING
Chapter 7 Highway Design for Safety
7.1.3 Geometry of Horizontal Curves
The horizontal curves are, by definition, circular curves of radius R. The elements of a horizontal curve are
shown in Figure 7.9 and summariz
Step 1: Input Data
Geometric data
Demand volume
Highway class (I, II, or III)
Field-measured speed (5%), or
Base freeow speed (BFFS)
Class III
Step 2: Estimate Free-Flow Speed
Fieldmeasured speed adjustments: ow rate, heavy vehicles
Capacity Analysis of Two
Lane Highways
Methodology given in Chapter 15
of HCM 2010.
Treated as Uninterrupted-Flow
facility.
Main difference about the traffic
flow: passing maneuvers take
place in the opposing lane of
traffic.
Passing- depends on the
avail
Earthwork
Terrain has a significant impact on
site design and costs.
To minimize earthwork and hence $,
Match with Existing Ground
Balance Cut and Fill
Volumes of Earthwork
Plot cross sections of existing and
proposed grade lines.
Cross sections typically
Vertical Curves
Chapters 9, 10 and 11,
Course Manual
Vertical Alignment
Vertical alignment of the highway
refers to its design in the profile
view.
Vertical alignment consists of
combinations of
Straight sections (tangents or grades)
Curves (vertical curv
Roadside Design
Chapter 18 from the CM
The Concept
Concept of forgiving roadside is
essential for the design and redesign
of roadways.
It should be anticipated that even in
a properly designed road,
vehicles would occasionally
leave the roadway for varie
Sight Distance
Refer to Ch 13 & 14 of the
Course Manual.
1
Importance
For safe and efficient operation drivers need to see ahead.
This ability to see sight distance
Simply, length of highway ahead
visible to the driver.
2
Guidelines
3
Short Titles
Green B
Highway Capacity Analysis
All guidelines provided in Highway
Capacity Manual Current Edition
is HCM 2010. Replaces HCM 2000.
Defines capacity as the maximum
hourly rate of flow that can be
expected to traverse a point or a
uniform section of a lane or a
r
Mass Diagrams
Chapter 20 of Course Manual
Mass Diagrams
The primary reason for calculating earthwork
quantities is to estimate the costs for
excavation and transporting the excavated
materials.
The mass diagram is a useful graphical form
for summarizing
Compound Curves
Chapter 7 of the Course Manual
Types of Horizontal Curves
Simple Circular Curves (discussed
already)
Compound Curves
Broken Back Curves
Reverse Curves
Broken-Back Curves
Two curves
deflecting in the
same direction
and joined by a
shor
Horizontal Curves
Ch 6 and 7 of CM
Geometric Design
Elements
Horizontal Alignment (Plan View)
Vertical Alignment (Profile View)
Cross Section (Lane Widths,
Shoulders, Cross Slopes, Medians
etc.)
Channelization
Horizontal Alignment
Plan view A series of ta
CE 411: Route Location and
Design
By
Prof. Sunanda Dissanayake
Spring 2015
1
Introduction
Basic definition of transportation : moving
people and goods from one place to another
safely and efficiently.
Extremely important for the economic
development.
S
Highway Safety
Ch 19 of the CM
Importance of Statistics
Various characteristics are studied
by examining/analyzing statistics.
Well established data sources are
available particularly at national
level.
Very useful in identifying trends,
problem areas e
A parabolic curve that is applied to make a smooth
and safe transition between two grades on a roadway
or a highway.
VPC: Vertical Point of Curvature
VPI: Vertical Point of Intersection
VPT: Vertical Point of Tangency
G1, G2: Tangent grades in percent
A: