Work Zone Mobility and Safety Program

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:

  • Speeds
  • Counts
  • Volumes
  • Delay times
  • Queue lengths

slide 9: Types of Data

System Outputs:

  • Email or text alerts
  • Changes to message signs
  • Website maps
  • Low voltage warnings
  • Ambient temperature

slide 10: Types of Data

Security & System Overrides:

  • Geo-fencing
  • 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:

  • Agency
  • Location
  • Road classification
  • Project goals
  • Surprises on the job
  • Type of construction

slide 21: Contact Info

Joe Jeffrey
Road-Tech Safety Services, Inc.
Phone: (530)672-0222

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