CE3600: Principles of Highway
and Traffic Engineering
Dr. J. Codjoe
Background
Graduated
2000 BS Agric. Engineering - Ghana;
2002 MS Civil Engineering (Transportation) Sweden
2014 Ph.D. Civil Engineering (Transportation) - LSU
Worked for 9 years in i
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LOUISIANA DEPARTMENT OF TRANSPORTATION AND DEVELOPMENT
Minimum Design Guidelines for Freeways
State law requires that the state highway system conform to these guidelines.
II
15 Minimum Vertical Clearance (ft) '
Width of Right-ofWay (it)
(a) Depressed
Example 42. On a section of a motorway, an accident occurs at 10:00 am at
point B (see Fig. 11.101 ). At first, the vehicles involved block the entire
carriageway. After 15min, one lane is cleared, and thereafter one lane of
traffic ows past point B.
Da
IV. Traffic Assignment (Part 1)
Trip generation
Trip distribution
Modal choice
Traffic assignment
Julius Codjoe
LSU
Trip generation
Trip distribution
Mode split
Transit
person trip
table (O&D)
Definition:
To estimate the
actual routes
used by all trip
IV. Traffic Assignment (cont)
Trip generation
Trip distribution
Modal choice
Traffic assignment
Julius Codjoe
LSU
Capacity Restraint:
(i) Concept of User Equilibrium (UE)
Assumptions
Users select routes based on travel times ONLY
Users know travel t
HIGHWAY GEOMETRIC DESIGN
PART II HORIZONTAL CURVES
Dr. J. Codjoe
HORIZONTAL ALIGNMENT
Purpose: to impose a gradual change in direction
along the roadway
Method: connecting two straight sections by
either simple curves, reverse curves, compound
curves, or
Highway Geometric Design
Part I Vertical Curves
Dr. J. Codjoe
Roadway Design Elements
Number of lanes
Lane width
Median type and width
Length of acceleration and deceleration lanes
Truck climbing lanes on steep grades
Curve radii
Roadway alignment for SSD
Highway Geometric Design
Part I Vertical Curves
(contd)
Dr. J. Codjoe
Example (2)
A 600-ft equal tangent sag vertical curve
has the PVC at station 170+00 and
elevation 1000 ft. The initial grade is -3.5%
and the final grade is 0.5%. Determine the
elevatio
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III. Modal Choice
Trip generation
Trip distribution
Modal choice
Traffic assignment
Dr. J. Codjoe
LSU
Mode Choice
Definition: the process of splitting
interzonal trips between the different
available modes
Importance
Transport policy (encourages wal
IV. Traffic Assignment (cont)
Trip generation
Trip distribution
Modal choice
Traffic assignment
Julius Codjoe
LSU
Capacity Restraint:
(i) Concept of User Equilibrium (UE)
Assumptions
Users select routes based on travel times ONLY
Users know travel t
Urban Transportation Planning
II. Trip Distribution
Trip generation
Trip distribution
Modal choice
Traffic assignment
Dr. J. Codjoe
LSU
Definition
The process of determining the number
of trips moving from one zone
(production) to another (attraction)
Example:
Consider a zone that has 60 dwelling units
Average income is $44,000
Find the number of trips per day generated by
this zone for each trip purpose using figures 12.2
to 12.5 (handout)
Find the percentage of households in each income category
Ref
IV. Traffic Assignment (Part 1)
Trip generation
Trip distribution
Modal choice
Traffic assignment
Julius Codjoe
LSU
Trip generation
Trip distribution
Mode split
Transit
person trip
table (O&D)
Definition:
To estimate the
actual routes
used by all trip
CE 3600 - Principles of Highway and Traffic Engineering
Homework Assignment #2
1. A -2% grade meets a +3% grade at station 50+00 with an elevation of 425 feet. Based on the
design considerations, we find that a vertical curve length of 1,000 feet is requi
CE 3600 - Principles of Highway and Traffic Engineering
Homework Assignment #3
1. The diagram below represents a "snapshot" of vehicles traveling on a segment of roadway.
The figure also shows their positions and speeds at an instant of time. An observer
CE 3600 Principles of Highway and Traffic Engineering
Homework Assignment #4
1. You have been asked to provide expert testimony in a traffic accident case. A collision has
occurred at a signalized intersection in which the plaintiffs vehicle was struck br
CE 3600 - Principles of Highway and Traffic Engineering
Homework Assignment #1
1. Determine the stopping sight distance required for a road with a 50 mph design speed on a
level grade. Next, compute and the stopping sight distance values at 50 mph at 1% i
192
CHAPTER 7 Geometric Design of Highways
Vertical Curve
VARIABLES
VPI 2 Vertical point of intersection (I)
VPC 2 Vertical point of curvature (I)
VPT : Vertical point of tangency (I)
l 2 Grade of initial tangent
3 = Grade of nal tangent
Length of