Work Zone Data
slide 1: Work Zone Data
Work Zone ITS Peer Exchange
May 22, 2013
slide 2: Agenda
- Types of Data
- Data for Work Zone Management
- Data for Evaluation of System Performance
- Lessons Learned
slide 3: Work Zone Data
- Transportation bill says we must collect it.
- Use it to improve traffic control safety and throughput.
- Also helps us allocate our limited resources more efficiently.
slide 4: Why Me?
- Started Road-Tech 12 years ago to pursue work zone ITS business.
- Past chair ATSSA ITS Council.
- ITS California member.
- Co-lead of California SHSP Work Zone Challenge Area.
- Work Zone ITS blog.
slide 5: Ground Rules
- This is not a lecture – it is a discussion.
- PLEASE disagree with me!
slide 6: Types of Data
- Real-time data = work zone management.
- Collected data = system performance/ planning data.
slide 7: Types of Data
- Primer contrasted project level measures with agency/program level measures.
- Our focus is on project level data.
- Don't focus just on systems operations measures in work zones.
- Choose measures that will work well both for work zone management and for later evaluation of system performance.
slide 8: Types of Data
Work Zone Performance Measures:
- Delay times
- Queue lengths
slide 9: Types of Data
- Email or text alerts
- Changes to message signs
- Website maps
- Low voltage warnings
- Ambient temperature
slide 10: Types of Data
Security & System Overrides:
- Manual message overrides
- Voltage levels
- Charge levels
slide 11: Possible Metrics for Work Zone Management
- Average speeds
- Number of incidents (speeds below XX MPH)
- Delay time
- Travel time
slide 12: Possible Metrics for Work Zone Management
- Speed variance – need for additional law enforcement
- Queue length (incentives/disincentives)
slide 13: Possible Metrics for Evaluation of System Performance
"Primer" says measures fall into three categories:
- Exposure measures (Pg 10)
- Volume or level of service.
- Reduction in volume through project limits.
- Lane closure lengths or hours.
- Safety measures (Pg 12 & 13)
- Number of fatal, injury, PDO crashes.
- Worker injuries or time lost.
- Mobility measures (Pg 16)
- Queue lengths.
- Delay times.
slide 14: Possible Metrics for Evaluation of System Performance
- Were the goals for the deployment achieved?
- Was the cost justified through improved safety and efficiency?
- What was benefit/cost ratio?
- Did it reduce delays? Frustration? Road rage?
- Did it reduce the expected number and severity of crashes? What should you use as a baseline?
slide 15: Importance of Raw Data
- Better "feel" for triggers and where to set them.
- Learn if trigger was one-time event or if slow traffic continues.
- Helps eliminate false alarms.
- Art versus science.
- Helps locate sensors where data is best indicator of flow.
- Check your data regularly!
slide 16: Speeds Over Distance Versus Spot Speeds
- Hayward – San Rafael Bridge during Bay Bridge closure.
- Micro versus macro data.
- Data which most agencies have not had before.
slide 17: Importance of Multiple Data Points
- Earlier notification.
- Smaller problem.
- Faster correction.
- Fewer secondary collisions.
- More accurate delay or travel times.
- Better identify location of incident.
- Where to send EMS.
- Where traffic control issues may need correction.
slide 18: Gathering Data
- Always place sensors upstream of longest possible queue.
- Watch data and adjust sensors as needed:
- Echoes off concrete barrier.
- Slow moving equipment.
- Some off ramps (especially truck scales).
- Areas where geometry causes slowing – narrow lanes, lane shifts, etc.
- Sensors may be moved on the job. RTMS units, in particular, may need to be re-aimed.
slide 19: Gathering Data
- Frequency of polling:
- More often for queue warning.
- Less often for delay times.
- Data format
- What formats do your agencies require?
- Create a data policy once you've found practices that work for your agency.
slide 20: Two Final Points
No such thing as too much data!
Best measures vary with:
- Road classification
- Project goals
- Surprises on the job
- Type of construction