1. The Tips and Tools to Successful Signal Timing Improvements
Prevent Accidents and Traffic Delays: The Art of Delivering and Maintaining Successful Signal Timing Improvements
The Tips and Tools to Successful Signal Timing Improvements
By: Joshua H. Pack, P.E.
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2. Meet Your Instructor
BS Degree from the University of California - Davis
Registered Civil and Traffic Engineer in California
Principal Civil Engineer and County Traffic Engineer at the County of Nevada (CA)
Previous experience as a Traffic Engineer for various SF Bay Area Municipalities
Developing Traffic Signal Timing Strategies and Methodologies
Intelligent Transportation System (ITS) Planning, Design and Construction
Signal Coordination on Numerous Congested Corridors
Signal Timing Review
Maintaining Traffic Signal Systems
Developing Consensus with Elected Officials and Key Policy and Decision Makers
Public Outreach

3. Why Improve Signal Timing?
Why develop traffic signal coordination in my jurisdiction?
FHWA estimates that 75% of the nation’s 260,000 traffic signals could be improved by updating equipment or timing plans
Poor signal timing accounts for up to 10% of all traffic delay in the United States
Improve mobility and reduce travel times
Reduce Greenhouse Gas (GHG) emissions and fuel consumption
Reduce the number of collisions
Reduce the total number of stops
Reduce the number of complaints from local residents and improve customer satisfaction

4. Webinar Outcomes and Course Goal
Bridge the gap between timing principals and real life application
“Context sensitive” signal timing
Steps to develop successful and sustainable timing improvements
Key timing and coordination parameters and measureables that directly impact traffic safety and operations

5. Course Description Consensus building
Developing realistic expectations
Data collection
Critical timing parameters
Traffic inequity
Infrastructure capabilities and limitations
Signal timing improvements – the unintended side effects
Microsimulation
Intelligent Transportation Systems (ITS)

6. Course Description Testing and implementing timing improvements
Develop regular system checks
Public outreach and customer service

7. Case Studies and Lessons Learned
Case Study 1 –County Supervisor Throws Wrench in Freeway Congestion Management
Cast Study 2 –Happy Mayor and Council Thwart Timing Improvements

8. Step 1 – Public Outreach and Consensus Building
What is the problem?
Who is our audience?
Elected officials and decision makers
Residents
Other members of the public
How do we develop consensus?
Engage your audience (public workshop, neighborhood meeting, etc.)
LISTEN to their concerns / complaints
Resolve issues within your control
Develop consensus on the problem scope
Developing realistic expectations
Follow up through additional communication
ESTABLISH TRUST WITH YOUR AUDIENCE!

9. Step 2 – Data Collection and Preliminary Scoping
CRITICAL AT DEVELOPING REALISTIC EXPECTATIONS
What is the scope of my project?
What is the existing status of my intersection or corridor?
What sort of planning level documentation will we ultimately develop?
What are my project goals (collision reduction, operational improvements?)
Traffic volumes
Minimum AM/PM scenarios
May want to consider other scenarios that may be corridor specific
Lunchtime
School peak
Weekends
Special Events
Emergency

10. Step 2 – Data Collection and Preliminary Scoping
Design and ITS
Intersection geometrics for each intersection
Existing field assets
Controller equipment
Detection equipment
Other relevant cabinet equipment
Communications infrastructure (fiber, copper, wireless, leased)

11. Step 2 – Finalize Size and Scope of Efforts
What will be the size and scope of your project, and it is in conformance with the thoughts and desires of your elected officials?
Will additional public outreach or workshops provide additional benefit?
Identify costs and timeframe to develop and implement timing program
Keep in mind potential Operation and Maintenance (O&M) costs
DEVELOP REALISTIC EXPECTATIONS!!!

12. Step 3 – Developing Timing Improvements
Not all trips are created equal!
Hierarchical approach to signal timing
Residents
Businesses
“Cut thru” traffic (perceived versus reality)
Basic signal timing – you giveth and you taketh away
Signal coordination
Balance the needs for efficiency with the impacts to local residents and businesses

13. Signal Timing – Green Phase Timing Parameters
Minimum Green (minimum initial)
Consider 4 seconds minimum for all approaches
Longer minimum green for through movements on major arterials
Gap Extension (passage time, vehicle extension)
Consider 2 seconds minimum for all approaches
Longer extension timing for through movements on major arterials
Maximum Green
Simulation software can help identify appropriate max timing
In absence of simulation software, minor approaches should serve traffic 95% of the time or more
Major arterials should balance need to serve traffic with needs and expectations of minor approaches

14. Signal Timing – Yellow / Red Phase Timing Parameters
Yellow Clearance
Use of posted speed limit versus critical (85th percentile speed)
3.0 seconds minimum for all approaches
Red Clearance
Many jurisdictions require no red clearance interval
Consider 1.0 second clearance interval uniform for all approaches
Yellow + Red Clearance helps reduce intersection conflicts
APPROACH SPEED
YELLOW INTERVAL
(mph)
(seconds)
25 or less
3.0 30
3.2 35
3.6 40
3.9 45
4.3 50
4.7 55
5.0 60
5.4 65
5.8

15. Signal Timing – Other Timing Parameters
Pedestrian Walk
Clearance Intervals
Bicycle Minimum Green
Bicycle Clearance Intervals
Dynamic Signal Timing
Added initial green
Variable gap extensions / gap reductions
Dynamic maximum green timing
Phase Recall Options
Minimum / Maximum recall
Pedestrian recall
Dual entry / simultaneous gap
Green / Pedestrian delay

16. Developing Traffic Signal Coordination Plans
Size and complexity depends on the approach
Use of microsimulation models (i.e. Synchro)
Bad data = bad signal timing

17. Signal Coordination – Key Measureables
Approach Delay and Approach LOS
Queue Length 95th Percentile
Total Delay
Total Stops
Fuel used
Dilemma Vehicles
Average Speed

18. Critical Timing Parameters
Time of day (when does it makes sense to activate and deactivate coordination?)
Corridors (and segments within corridors)
Cycle length
Split timing for each phase (amount of time each phase received in a given cycle)
Timing preferences and traffic equity
“Cut-thru” traffic and residential impacts

19. Microsimulation – Only the 1st Step!
Pros
Great at developing efficient network
Are aware of local, state and federal signal timing standards
Common pitfalls
May employ “optimized” approach in favor of approach that balances public expectations
May be unaware of localized traffic issues
Reasonableness review
Reliance on default values

20. EB I-580 Worst PM Commute in Bay Area
Hopyard / Stoneridge intersection
Oakland/SF
San Jose/Fremont
Concord/Walnut Creek
Central Valley/Livermore

21. Blue – Local Traffic
Yellow – “Cut Thru’ Traffic

22. Blue – Local Traffic
Yellow – “Cut Thru’ Traffic

23. What is the role of ITS infrastructure?
Pros
Improve ability to implement traffic signal coordination
Improve ability to monitor signal coordination
Improve ability to troubleshoot and adjust coordination
Implement emergency signal timing and coordination if needed
Robust data collection possibilities
Many devices now have ITS capabilities
Video assets at key locations
Sharing data and video with other agencies, departments, and the public
Share cost sharing opportunities with partners – opportunities for public/private cost sharing?
Cons
COST!
Significant increase in maintenance and replacement costs

24. Step 4 - Test and Implement Signal Coordination
Activate and testing timing
Fine tuning and observation
“After” data collection

25. Step 5 – Follow up data collection and reporting
Keeps members of the public, elected officials and decision makers informed of improvements
Various data to consider including:
Before and After travel time studies
GHG emission reductions
Reduction in number of stops
Level of Service
Overall delay
Cut-thru analysis / volume comparison??
Consider delivering in a public setting (i.e. Council/Board meeting?)
Goal is to quantify improvements of key measureables and educate your elected officials and decision makers

26. Step 6 – Now what????? Follow up data collection and recalibration
Annually
When major projects are constructed in the area
Regular checks of field equipment
Inquiries from the public
When to consider changes or improvements?

27. Final Thoughts and Conclusions
Signal timing and coordination can significantly improve corridor performance, reduce travel times, GHG emissions and collisions and provide a valuable service to your community.
Recommend early public outreach to identify critical corridors and “hot spots” and to gain support from elected officials, key decision makers and the general public
Data collection critical at developing signal timing and coordination plans and quantifying system improvements
Key signal timing parameters can improve system operations and reduce the number of collisions
Efforts do not stop and successful implementation
OWNERSHIP!

28. End of Presentation Joshua H. Pack, P.E.
Principal Civil Engineer / County Traffic Engineer
County of Nevada – Department of Public Works
(530)

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