SIGNAL TIMING WITHOUT TRAFFIC COUNTS

Transportation Research GroupUniversity of Nevada, Reno 2012 ITE District 6 Annual Meeting

SIGNAL TIMING WITHOUT TRAFFIC COUNTS

Zong Z. Tian, Ph.D., P.E.University of Nevada, Reno

1

http://unr.edu/homepage/zongt/

Presented by

Jim Poston

Regional Transportation Commission of Washoe

County

http://unr.edu/homepage/zongt/


Overview

Signal timing practice

Case study My magic tool

Results

Conclusions

2


Signal Timing Practice3

Turning movement counts (15-30% total cost)

Computer model and timing optimization (50~70%)

Field implementation and fine tune (10~20%)

Timing maintenance (<5%)


Coordination parameters4

Cycle length

Phase sequence

Phase split

Phase offset


What Is Really Needed?5

Phase demand/split

How to obtain phase split estimate based on volumes existing timing controller log

Existing splits are generally good if no cycle change is needed

6

7

Inte

rsec

tion

an

d d

ista

nce

NB


Real-world Issues8

Variable speeds

Early releases

Wrong offset reference Start or end of coordinated phases TS2-1st Green or First Ring

Signal out of coordination Preemption Pedestrian Loss communication

Clock time

9

Cycle = 120

10

NB


Before-After12

After BeforeTotal = 4’04” Total = 6’15”


Before-After13

After BeforeTotal = 4’04” Total = 6’15”


SMRTSignal Monitoring & Retiming Tool

14


15


16

GPS


SMRT17


SMRT18


SMRT19


CONCLUSIONS20

Signal timing can be done without traffic counts (15%+ saving)

Significant improvement by simply changing phasing sequences15% travel time saving20~80% saving in stops

My magic “Timer”


?21

SIGNAL TIMING WITHOUT TRAFFIC COUNTS

Documents

reno2012 ite district

timing optimization

timing maintenance

signal signal timing

traffic countszong

total cost computer

field implementation

fine tune