Chapter 16: Principles of Intersection Signalization cont'

1
Lecture 7

• Chapter 16 Principles of Intersection
  Signalization (cont.)

2
Objectives

• Understand concept of delay and how it relates to
  the traffic stream

3
Intersection Delay

• What are the different measures of delay?

4
Intersection Delay

• What are the different components of delay?
• Uniform Delay (UD)

5
Intersection Delay

• What are the different components of delay?
• Random Delay (OD)

6
Intersection Delay

• How is signalized intersection delay modeled?
• d 0.90 UD RD

7
Signal Cycle

• What cycle minimizes signalized intersection
  delay?
• Co minimum delay cycle (sec)
• L total lost time (sec)
• (v/s)c saturation flow ratio for critical
  movement

8
Signal Cycle

• How sensitive is delay to cycle time?
• ¾ C 1 ½ C
• Why is this significant to a traffic engineer?

9
Intersection Overflow Delay

• What would long term overflow look like?

10
Intersection Overflow Delay

• Are there any practical problems associated with
  the delay model?

11
Intersection Delay Bridging the Gap

• There are a variety of delay models
• Australian
• TRANSYT
• HCM (isolated intersection)
• Based on theoretical UD and OD
• Calibrated using X2

12
Intersection Delay Urban Signalized
Intersections

• Does arrival at an intersection affect delay?
• link to Excel file

13
Intersection Delay An Approximation

• No claim is made that the formulas are correct,
  but rather that they yield answers which do not
  violate elementary logic in the region of v/c
  near unity where neither the steady-state nor the
  oversaturation models can be expected to yield
  reasonable results.

14
Intersection Delay Simulation

• How have these delay models been validated?

15
Intersection Stopped Delay Conversion

• What about the constant, 1.3, used to convert
  approach delay to stopped delay?

16
Intersection Delay Sample Calculations

• Given
• v 1100 vph
• s 2000 vphg
• C 120 sec
• g/C 0.52
• Find
• Average stopped delay for the first 15 minutes of
  the specified conditions

17
Conclusion

• New Homework Assignment
• Check web for HWK 3
• Homework Assignment due
• Assignment 2
• Lab Announcements
• Data collection Monday, next week