exploring pedestrian responsive traffic signal timing strategies in urban areas
TRANSCRIPT
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Exploring Pedestrian Responsive Signal Timing Strategies in
Urban AreasIBPI Webinar
January 29, 2015
Sirisha Kothuri, PhDResearch Associate
Civil and Environmental Engineering
Portland State University
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Presentation Roadmap
2Introduction | Behavior | Delay| Simulation| Conclusion
1. Introduction
2. Pedestrian Crossing Behavior
3. Pedestrian Delay Measurement
4. Simulation Modeling
5. Wrap-Up
1. Conclusions
2. Implications and Recommendations
3. Future Work
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Introduction
Growing emphasis on active transportation
Walking healthy, livable communities
Increase in walking trips
3Introduction | Behavior | Delay| Simulation| Conclusion
Source: Data from Pucher et al.,(2011)
National Walking Trends Local Commute Shares - Walk 4%Source: City of Portland, Climate Action Plan
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Introduction
Pedestrian fatalities
6% increase in 2012
73% - urban areas
20% - intersections
Poor crossings
Deter people from walking
Unsafe crossing behavior
4
Source: NHTSA, Traffic Safety Facts 2012
“On average, a pedestrian was killed every 2 hours and injured every 7 minutes in traffic crashes”
Fatality Trends
Introduction | Behavior | Delay| Simulation| Conclusion
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Motivation
5
Delays affect pedestrians disproportionately
“Everyone is a pedestrian”
Incr
easi
ng
Pri
ori
ty
Introduction | Behavior | Delay| Simulation| Conclusion
How do we translate “pedestrian first” policies into specific operational strategies at intersections?
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Research Questions
What factors influence crossing decisions? Perceptions of delay? Demographics
Trip characteristics
Perceptions of safety
Signal controller pedestrian MOE’s? Actuations
Delay
Impacts of control strategies on different modes? Traffic Regimes? Change in operation
6Introduction | Behavior | Delay| Simulation| Conclusion
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Signal Timing 101
7
Signal operation
Coordination Free
Pedestrian detection
Recall
Actuated
Introduction| Behavior| Delay| Simulation| Conclusion
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Research Questions
What factors influence crossing decisions? Perceptions of delay? Demographics
Trip characteristics
Perceptions of safety
Signal controller pedestrian MOE’s? Actuations
Delay
Impacts of control strategies on different modes? Traffic Regimes? Change in operation
8Introduction | Behavior | Delay| Simulation| Conclusion
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Pedestrian Crossing Behavior - Review
9
Demographic Characteristics
• Age • Gender• Group status
Crossing Characteristics
• Delay• Traffic volumes• Crossing speed
Infrastructure
• Pushbutton feedback
• Countdown timer• Automated
detection
MacGregor et al. (1999); Diaz (2002); Yanfeng et al. (2010); Wang et al. (2011); Bradbury et al. (2012)
Demographics
CrossingDunn et al. (1985); Knoblauch et al. (1996); Hamed (2001); Diaz (2002) HCM (2010); Wang et al. (2011);
InfrastructureHughes et al. (2000); Keegan et al. (2003); Eccles et al. (2004); Van Houten et al. (2006)
Introduction | Behavior | Delay| Simulation| Conclusion
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Gaps
Role of perceived safety and compliance in crossing decisions?
Perception of delay
Demographics
Trip characteristics
Infrastructure
10Introduction | Behavior | Delay| Simulation| Conclusion
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Methodology
11
Intercept survey of crossing pedestrians
Survey administered using a tablet
11 questions, < 5 minutes to complete
Introduction | Behavior | Delay| Simulation| Conclusion
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Survey Locations
12Introduction | Behavior | Delay| Simulation| Conclusion
RecallN = 140
RR = 70%
ActuatedN = 53
RR = 77%
RecallN = 93
RR = 68%
ActuatedN = 81
RR = 66%
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Descriptive Statistics
13Introduction | Behavior | Delay| Simulation| Conclusion
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Trip Characteristics
14Introduction | Behavior | Delay| Simulation| Conclusion
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Perceptions
15Introduction | Behavior | Delay| Simulation| Conclusion
How satisfied are you with the amount of time the signal gives you to cross at this intersection?
How satisfied are you with the amount of time you have to wait before crossing at this intersection?
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Perceptions of Safety
16Introduction | Behavior | Delay| Simulation| Conclusion
In general, how safe do you feel crossing at this intersection?
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Attitudes
17Introduction | Behavior | Delay| Simulation| Conclusion
Please indicate your level of agreement with the following statement: My crossing decisions are influenced by concerns about safety.
Please indicate your level of agreement with the following statement: My crossing decisions are influenced by concerns about whether I am violating traffic code.
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Model Results – Crossing Decisions
18Introduction | Behavior | Delay| Simulation| Conclusion
N= 362, -2LL = 242.53, Model χ2 =55.42, df = 17, R2= 0.25
Please indicate your level of agreement with the following statement: My crossing decisions are influenced by concerns about safety.
Base CaseLength < 5 minsShopping TripsAge (40-65)Freq 4+days/wk
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Corridor Level Models - Delay Satisfaction
19Introduction | Behavior | Delay| Simulation| Conclusion
N= 217, -2LL = 155.08, Model χ2 =33.33, df = 14, R2= 0.25
How satisfied are you with the amount of time you have to wait before crossing at this intersection?
Base CaseActuated IntAge (40-65)
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Findings
20
Limitations
Crossing decisions Safety Trip PurposeGroups
DelayPerception of safetyTime constraintsAgeInfrastructure
Representative sample Older adultsChildrenDisabled
Other languagesSpanish
More locations
Introduction | Behavior | Delay| Simulation| Conclusion
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Research Questions
What factors influence crossing decisions? Perceptions of delay? Demographics
Trip Characteristics
Perceptions of safety
Signal controller pedestrian MOE’s? Actuations
Delay
Impacts of control strategies on different modes? Traffic Regimes? Change in operation
21Introduction | Behavior | Delay| Simulation| Conclusion
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Pedestrian Delay Estimation - Review
22
Performance measures to characterize pedestrian service
Estimated delay is not accurate (Hubbard, 2007)
Why estimate delay when we can measure it?
dp =0.5 (C−g)2
C
dp = average pedestrian delay (s/p)C = cycle length (s)g = effective walk time (s)
Introduction| Behavior| Delay| Simulation| Conclusion
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Pedestrian Actuations and Delay
23
Record pushbutton actuations
Type 2070 signal controllers
Voyage software
Two novel validated methods
Transit priority logs
Volume logs
Introduction| Behavior| Delay| Simulation| Conclusion
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Pedestrian Actuations and Delay
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Source: demo.portal.its.pdx.edu/pedbike
Introduction| Behavior| Delay| Simulation| Conclusion
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Research Questions
What factors influence crossing decisions? Perceptions of delay? Demographics
Trip Characteristics
Perceptions of safety
Signal controller pedestrian MOE’s? Actuations
Delay
Impacts of control strategies on different modes? Traffic Regimes? Change in operation
25Introduction | Behavior | Delay| Simulation| Conclusion
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Delay Optimization - Review
26
Early efforts focused on reducing vehicle delay Webster (1958), Little (1975)
Few studies on optimizing signal timing for pedestrians
Analytical Simulation
Ped delay costs (Noland, (2005))
Split phasing (Tian et al. (2001))
Two stage crossing (Wang (2010))
Offsets (Bhattacharya et al. (2005))
Cycle lengths (Ishaque et al. (2006))
Type of ped crossing (Ishaque et al. (2007))
Phasing (Vallyon et al. (2011))
Green splits (Roshandeh et al. ((2013))
Introduction| Behavior| Delay| Simulation| Conclusion
Gap: No studies on impacts resulting from change in mode of operation
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Simulation Model
27Introduction| Behavior| Delay| Simulation| Conclusion
Inputs VISSIM Outputs
Volumes Speeds
Signal Timing Delay
Travel time
Queue Length
RBC ControllerGeometry
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Site Selection
28Introduction| Behavior| Delay| Simulation| Conclusion
Multnomah and 11th Multnomah and 13th Multnomah and 15th
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Time of Day Models
29
Network volume
Average delay per person
Auto and ped volumes are greater during mid-day and PM peak
Ped volume greater during mid-day
Overall average delays per person are higher during mid-day
Ped delay is greater compared to auto delay for all time periods
Introduction| Behavior| Delay| Simulation| Conclusion
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Hypothetical Network
30
Based on the calibrated Multnomah network
All Multnomah ped movements on recall and rest-in-walk
All side street vehicle and ped movements are actuated
Flows varied in three ranges – High, Med, Low
Introduction| Behavior| Delay| Simulation| Conclusion
Scenario V/C Ratio Range
Low < 0.3
Medium 0.3 – 0.7
High > 0.7
Scenario Ped Phase Freq
Low < 30%
Medium 30% – 70%
High > 70%
Auto V/C Ratios Pedestrian Phase Frequency
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Models
31
A total of 18 scenarios were constructed, 9 per mode of operation
Introduction| Behavior| Delay| Simulation| Conclusion
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Comparison – Existing Timing
32
% Change in Delay =Free Delay − Coordinated Delay ∗ 100
Coordinated Delay
Introduction| Behavior| Delay| Simulation| Conclusion
Low – Low = Low Auto Low Ped
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Optimized Timing
33Introduction| Behavior| Delay| Simulation| Conclusion
70 s
90 s
Optimized splits and offsets, while cycle length
constant (80s)
Optimized cycle lengths, splits and offsets
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Higher Cycle Lengths
34Introduction| Behavior| Delay| Simulation| Conclusion
Higher cycle lengths benefit coordinated
movements
Actuated ped delay ~ 47-53s (120s CL)~ 35-38s (80s CL)
~13-18s (Free)
Actuated ped delay ~ 52-53s (120s CL)~ 34-35s (80s CL)
~17-33s (Free)
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Division Street Case Study - I
35Introduction| Behavior| Delay| Simulation| Conclusion
Existing volume corresponds to medium auto – low ped scenarioExpected finding: Free delay < Coordinated delay
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Division Street Case Study -II
36Introduction| Behavior| Delay| Simulation| Conclusion
Similar trends as seen on Multnomah St network
Delay for all modes is lower during free operation
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Strategies
37Introduction| Behavior| Delay| Simulation| Conclusion
COORDINATEDShort Cycle Lengths
FREE
Ped Act. Frequency (side st.)
V/C
(m
ajo
r st
.)
Low<30%
Medium30%-70%
High>70%
COORDINATEDManage Ped Service Response
PED RECALL
< 0
.50
.5 –
0.8
> 0
.8
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Pedestrian Responsive Strategies
Inputs Traffic volumes
Pedestrian actuations and delay
Infrastructure Detection
2070 Controllers
Locations High pedestrian traffic generators
Intersections with high pedestrian delay
Intersections with low compliance
38Introduction| Behavior| Delay| Simulation| Conclusion
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Permissive Length – Field Deployment
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Scenario 2 (highest PL) – statistically significant reductions in pedestrian delay
Introduction| Behavior| Delay| Simulation| Conclusion
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Conclusions
Safety plays a larger role than compliance in crossing decisions
Trip purpose and group status influence crossing decisions
Time constraints and type of pedestrian detection infrastructure influence a pedestrian’s satisfaction with delay
40Introduction| Behavior| Delay| Simulation| Conclusion
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Conclusions
Free operation is generally beneficial for pedestrians
Coordination primarily benefits major street through movements
Treating all users equally, these strategies are recommended:
Free operation at V/C < 0.5
Coordination with managed response for 0.5 < V/C < 0.8
Coordination with short cycle lengths for V/C > 0.8
41Introduction| Behavior| Delay| Simulation| Conclusion
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Implications and Recommendations
Use existing resources for performance measurement
Consider all users while developing signal timing
Trade offs Safety vs. Efficiency
Pedestrian delay vs. Auto delay
3 E’s for promoting pedestrian compliance and safety
42Introduction| Behavior| Delay| Simulation| Conclusion
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Areas for Future Research
Continuing investigation into control strategies to benefit pedestrians
Impacts of increased permissive length on other modes
Development of priority pedestrian service
Current NITC funded project titled “Improving Walkability Through Control Strategies at Signalized Intersections”
43Introduction| Behavior| Delay| Simulation| Conclusion
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Thank you!
• Dr. Monsere
• Dr. Bertini, Dr. Clifton, Dr. Fountain
• Peter Koonce, Ty Reynolds – City of Portland
• Alex Kiheri - PTV
• Miranda Wells - HDR
• TREC/NITC
• ITS lab members, PhT colleagues
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• Kothuri, S., Reynolds, T., Monsere, C. and P. Koonce. Preliminary Development of Methods to Automatically Gather Bicycle Counts and Pedestrian Delay at Signalized Intersections. In Proceedings of the 90th Annual Meeting of the Transportation Research Board, Transportation Research Board of the National Academies, Washington D.C., 2012.
• Kothuri, S., Reynolds, T., Monsere, C. and P. Koonce. Testing Strategies to Reduce Pedestrian Delay at Signalized Intersections: A Pilot Study in Portland, Oregon. In Proceedings of the 92nd Annual Meeting of the Transportation Research Board, January 13-17, 2013.
• Kothuri, S., Clifton, K., and C. Monsere. Insights into Pedestrian Attitudes and Perceptions of Delay, Safety, and Crossing Decisions at Signalized Intersections. In Proceedings of the 93rd Annual Meeting of the Transportation Research Board, January 12-16, 2014.
• Kothuri, S.M, Koonce, P., Monsere, C. and Reynolds, T. Exploring Thresholds for Timing Strategies on a Pedestrian Active Corridor. In 94th Annual Meeting of the Transportation Research Board Compendium Papers, Washington DC, January 11-15, 2015.
References
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Contact Information
Sirisha Kothuri, Ph.D.Research Associate
Civil and Environmental Engineering
Portland State University
Phone: 503.725.4208
Email: [email protected]
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