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Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
Pedestrian Timing Strategies at Large Signalized Intersections
Zong Tian, Ph.D., P.E.Department of Civil & Environmental Engineering
University of Nevada RenoReno, NV 89557
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
OVERVIEW
Safety – Efficiency Issue• Impact of pedestrian timing on signal operations
Pedestrian Timing Strategies• Two-stage crossing• Split phasing• Exclusive ped phase
Summary and Conclusions
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
PED. CROSSING AT TRAFFIC SIGNALS
Pedestrian crossing concurrent with parallel vehicle movementSufficient time must be provided to allow pedsafely crossing
Green >= WALK + FDWConflict with turning vehicles
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
SAFETY VS. EFFICIENCY
Safety EfficiencyLong WALK + FDW Long Green (Minor St.)
Less Green (Main St.)Ped. Protected Phase Increased Lost Time
(Separate Ped and Vehicles) Less Capacity
Safety Efficiency
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
2008 Nevada Fall Transportation Conference
LARGE INTERSECTIONS
Minor St.
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
ISSUES
Low vehicle demand but long ped timeTwo-stage crossing = longer ped delaySignificant impact under split phasingCoordination issue (ped time treatments)
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
TWO-STAGE PEDESTRIAN CROSSING
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
TWO-STAGE PEDESTRIAN CROSSING
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
TWO-STAGE PEDESTRIAN CROSSING
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
TWO-STAGE PEDESTRIAN CROSSING
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
TWO-STAGE PEDESTRIAN CROSSING
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
TWO-STAGE PEDESTRIAN CROSSING
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
PEDESTRIAN TIMING SCENARIOS
“Pedestrian Delay Models at Signalized Intersections Considering Signal Phasing and Pedestrian Treatment Alternatives” (09-2537) by Wang et al.
• One-stage crossing• Current two-stage without overlaps• Two-stage with overlaps
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
SPLIT PHASING
Sequentially providing green and serving the two opposite approaches
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
PED. TREATMENT UNDER SPLIT PHASING
Left-turn green arrow(Protected LT)
No left-turn arrow(Permitted LT)
Dynamic display(Protected/Permitted)Acknowledgement: Some of the following pictures were borrowed from a presentation by Scott Wainwright of FHWA
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
T im e
** Two Pedestrian Splits
PROTECTED LEFT TURN
N
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
SB Vehicles Need 30” Green per Cycle
NB Vehicles Need 15” Green
Peds Need 5” Walk + 30” FDW
Total Vehicle Need = 45”Total Ped Need = 70”
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
T im e
** One Pedestrian Split
PERMITTED LEFT TURN
N
Total Vehicle Need = 45”Total Ped Need = 35”
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
** One Pedestrian Split
a) W ith C onflicting Pedestrian C rossings on B oth Sides
b) W ith C onflicting Pedestrian C rossings on East Side
N
PROTECTED/PERMITTED LEFT TURN
Total Vehicle Need = 45”Total Ped Need = 35”
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
** One Pedestrian Split
c) W ith C o n flict in g P ed estria n C r os sing s o n W est Sid e
d) W ith o ut C o n flict ing Ped estria n C ro ssin g s
N
PROTECTED/PERMITTED LEFT TURN
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
PROTECTED/PERMITTED LEFT TURN
Φ7 Φ9*
Φ1 Φ2
Φ5 Φ6
Φ3Φ10*
Φ8 (Ped Left)
Φ4 (Ped Right)
Ring 1
Ring 2
Ring 3
Ring 4
* Note: It may require to output φ9 and φ10 load switches to φ8 and φ4, respectively
e) Controller Phase and Ring Structures
N
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
Back Panel Wiring
Ph.8 N X T
Ph.8 O N
Ph.8 C H K
Ph.8 PO
Ph.8 O M T
Ph.8 H LD
Ph.8 PD
Ph.8 V D
Ph.7 N X T
Ph.7 O N
Ph.7 C H K
Ph.7 PO
Ph.7 O M T
Ph.7 H LD
Ph.7 PD
Ph.7 V D
Ph.4 N X T
Ph.4 O N
Ph.4 C H K
Ph.4 PO
Ph.4 O M T
Ph.4 H LD
Ph.4 PD
Ph.4 V D
Ph.3 N X T
Ph.3 O N
Ph.3 C H K
Ph.3 PO
Ph.3 O M T
Ph.3 H LD
Ph.3 PD
Ph.3 V D
D iode device
LE G EN D
V D = V ehicle D etectorPD = Ped D etectorH LD = Phase H oldO M T = Phase O m itPO = Ped O m itC H K = C heck C allsN X T = N ext PhaseO N =Phase O n
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
NO PED ON WEST LAG CROSSWALK(NB GREEN ARROW)
NB Approach
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
WITH WEST LAG PED (NB GREEN BALL)
NB Approach
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
STATIC OR DYNAMIC SIGN
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
LAS VEGAS PROTECTED/PERMITTED
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
* Reduced Pedestrian Splits
TWO-STAGE CROSSING
Tim e
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
EXCLUSIVE/SCRAMBLE
Tian, Z., Urbanik, T., Engelbrecht, R., and Balke, K. Pedestrian Timing Alternatives and Impacts on Coordinated Signal Systems Under Split Phasing Operations; Transportation Research Record 1748, pp. 46-54, 2001.
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
-1500
-1000
-500
0
500
1000
1500
0 100 200 300 400
Pedestrian Volume, ped/hr
Tim
e Sa
ving
s, s
ec/h
r
γ =0.2
γ =0.5
γ =1.0
γ =1.5
γ =2.0
Excl
usiv
e B
est
Conc
urre
nt B
est
Model Elements:• Ped Volume• Cycle Length• γ = (Ta + Tb)/tp• Ped Time (tp)
Data for the Figure:• Cycle = 100 sec• tp = 35 sec
EXCLUSIVE VS. PROTECTED LT MODEL
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
COORDINATED SIGNALS
Two timing alternatives to handle pedestrians• Ped timing accommodation
• Longer cycle• No ped timing accommodation
• Out of synch/Transition
Tian et al. (2000) . “Pedestrian Timing Treatment on Coordinated Signal Systems”, Proceedings of ICTTS’2000, ASCE, Beijing, China.
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
SUMMARY AND CONCLUSIONS
Efficiency SafetyTwo-stage crossing strategiesSplit phasing Exclusive/scramble phase Coordinated signals (to be continued…)
Transportation Research GroupUniversity of Nevada, Reno
2009 TRB Pedestrian Workshop
Tian’s website at UNR:
http://unr.edu/homepage/zongt