transportation research group university of nevada, reno 2012 ite district 6 annual meeting signal...

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

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

transportation research group university of nevada, reno 2012 ite district 6 annual meeting signal...

Documents

ite district

timing optimization

timing maintenance

traffic counts zong

magic tool results conclusions

total cost computer

field implementation

fine tune