Work Zone Mobility and Safety Program
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Oregon's Work Zone Traffic Analysis Program (Presentation)

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Contact Information: WorkZoneFeedback@dot.gov

Slide 1. Oregon's Work Zone Traffic Analysis Program

Oregon highway

Oregon Department of Transportation
90 Years Connecting Communities and Business

FHWA Work Zone Rule Virtual Workshop

November 6, 2008

Irene Toews, P.E.
Oregon Department of Transportation

Jeremy Jackson, E.I.T.
Oregon Bridge Delivery Partners

Oregon Bridge Delivery Partners™ logo

Oregon Department of Transportation logo

Slide 2. Oregon's Work Zone Traffic Analysis

  • Why do we do it?
  • What do we do?
  • How do we do it?

Slide 3. Why do we do it?

  • Work Zone Traffic Analysis Tool
  • Timeline
    • May 2004 – Oregon Bridge Delivery Program Starts
    • Summer 2005 – WZTA is created in spreadsheet form
    • Summer 2006 – WZTA is expanded for statewide use
    • Fall 2006 – ODOT WZTA Manual is revised
    • October 2008 – WZTA online tool goes live

Slide 4. What do we do?

  • Determine safe times for lane closures
    • Times when volumes are low enough that travel behavior is not significantly affected.
  • Determine Mobility Impacts – Delay Estimates
    • Work Zone
    • Segment
    • Corridor

Slide 5. WZTA Background

  • OTIA III Bridge Locations
  • Statewide Mobility Corridors Defined

Oregon highway map showing bridge locations on I-5, I-84, US 101, US 97, US 30, US 26, 229, US 20, US 199, and Routes 6, 18, 34, 36, 126, 38, 42, 35, 58, 138, 62, 140, 66, 26, 31, and 395

Slide 6. Mobility Management and Delay Thresholds

  • I-5 South Corridor (Eugene to CA State Line)

Oregon highway map showing interstates, U.S. highways, and state routes and highlighting I-5 from Eugene south to Califiornia border

Slide 7. Mobility Management and Delay Thresholds

  • Segment 4-C (US 199 to CA State Line)

Oregon highway map showing interstates, U.S. highways, and state routes and highlighting US 199 south to California border

Slide 8. Mobility Management and Delay Thresholds

  • Length: 55 miles
  • Delay Threshold: 7 minutes

Portion of Oregon highway map highlighting section of I-5 between Grants Pass and California border

Slide 9. Mobility Management and Delay Thresholds

  • Corridors broken into segments
  • Delay thresholds assigned to segments
  • Delay thresholds to be enforced 24/7/365
  • Detailed delay estimates are needed to help manage mobility
  • Individual delays must be aggregated

Portion of Oregon highway map highlighting section of I-5 between Grants Pass and California border

Slide 10. How do we do it?

  • Work Zone Traffic Analysis Tool
    • Requires only an internet connection and browser
    • Up-to-date data
    • Analysis results stored on server
    • 5–15 minutes per analysis
    • Output
      • Lane closure charts
      • Delay estimates
      • Other…

Slide 11. How Does It Work?

  • Gather data
  • Adjust data
    • Heavy vehicles
    • Seasonal variations
    • Weekday/weekend
    • Growth rates
  • Identify free flow threshold
  • Compare

Slide 12. Where Does the Data Come From?

  • ODOT Manual Count Database
  • ODOT Integrated Transportation Information System (ITIS)
    • ODOT Highway Inventory
    • Average Daily Traffic
    • Growth rates
    • Truck percentages
  • ODOT Traffic Database
    • Daily/Seasonal Trends & Automatic Traffic Recorder Data
  • GIS
    • UGB/MPO
    • Region Boundaries

Slide 13. What's a Free Flow Threshold?

  • The maximum sustainable volume that yields average travel speeds at or near free flow conditions
  • FFT depends on a number of factors

Photo of cranes in work zone next to temporary lane marked with cones  Photo of traffic in lane next to temporary lane marked with cones

Slide 14. Using the WZTA Tool

Choose your location – Method 1

  • Select Highway # and MP

The highway and milepoint portion of the Work Zone Traffic Analysis tool, highlighting highway 1 and milepoint 1 on a scale of valid milepoints from 1 to 32  Screenshot of the Work Zone Traffic Analysis tool showing an Oregon highway map, location information, and traffic data and highlighting the highway and milepoint section

Slide 15. Choose Your Location – Method 2

Use GIS map to select location

Screenshot of Oregon GIS map showing selection box for nearby highways with two highway numbers, milepoints, names, directions, and LRS

Slide 16. Year of Analysis

  • Inputting the year of analysis yields projected traffic data

The traffic data portion of the Work Zone Traffic Analysis tool, highlighting year of analysis (2008), linear growth rate (2.23%), existing ADT year (2007), existing ADT (25500), analysis ADT (26069), existing DHV (2856), analysis DHV (2920), percent trucks (36.53%), PCE factor (2.5), free flow threshold (1500 PCE/hr), and analysis ATR (20-020)  Screenshot of the Work Zone Traffic Analysis tool showing an Oregon highway map, location information, and traffic data and highlighting the traffic data section

Slide 17. Output – Lane Closure Chart

Lane closure chart – Weekday

Chart for I-5 Fairgrounds Interchange at Roseburg, southbound, weekdays, for each month Monday through Friday, showing closure type, milepoints, region, roadway type, terrain speed limit, percentage of trucks, PCE, ADT, ATR, and highlighting periods for each month and day of the week above PCE limit

Slide 18. Closure Chart Uses

  • Used primarily in the planning and design phases
  • Planning: May influence final design
  • Design: Project specifications
  • Construction: Short notice issues

Chart for I-5 Fairgrounds Interchange at Roseburg, southbound, weekdays, for each month Monday through Friday, showing closure type, milepoints, region, roadway type, terrain speed limit, percentage of trucks, PCE, ADT, ATR, and highlighting periods for each month and day of the week above PCE limit

Slide 19. Output – Delay Estimates

Table of one-hour time periods from 10 a.m. to 7 p.m., showing delay estimates for each hour, ranging from 0 at 10-11 a.m. to 211 at 4-5 p.m.

Grid chart showing aggregate delay summaries for I-5, segment 4-B, northbound for Monday, Tuesday, Wednesday, and Thursday, highlighting 1- to 3-minute delays from 1:30 to 4:30 p.m. and 3- to 5-minute delays from 2:30 to 4 p.m. from May to September

Slide 20. An Example of Work Zone Context

  • Horizontal geometry = 4 degree curve
  • Vertical geometry = 4–6% grade

Enhanced Oregon highway map highlighting a portion of US 99 and I-5 with 4 to 5 percent vertical grades and 4 degree curves

Slide 21. Traffic Planning Sheet (TPS)

Outputs include:

  • Roadway profile
  • Straightline diagrams
  • Horizontal curve table
  • Vertical grade table
  • Vertical type table

Slide 22. Traffic Planning Sheet (TPS)

Roadway Profile

Diagram of road elevation from 507 to 2529 feet for milepoints 94.85 (950 feet), 93.85 (1100 feet), 92.85 (1200 feet), 91.85 (1550 feet), 90.85 (1855 feet), 89.85 (1900 feet), and 88.85 (1800 feet), with the begining marked at 1500 feet between milepoints 92.85 and 91.85, midpoint marked at 1520 feet at milepoint 91.85, and ending at 1800 feet between milepoints 91.85 and 90.85.

Slide 23. Traffic Planning Sheet (TPS)

Straightline Diagram

Diagram of percentage of trucks, ADT, horizontal curve, vertical grade and type, ATR, and work zone size for milepoints 94.85, 93.85, 92.85, 91.85, 90.85, 89.85 and 88.85

Slide 24. ATR Graphing Tool

  • Allows for the graphing of actual volumes from an Automatic Traffic Recorder (ATR) over a user defined period
    • Albany ATR
    • October 6, 2007 to October 9, 2007

Graph of traffic volume from October 6 to October 9 for two types of users showing volume ranging from 200 to 3200 vehicles per hour, with the peak of 3200 at 8 and 10 a.m. on October 6

Slide 25. Summary

  • Delay estimates and work windows can be generated quickly
  • Ability to predict delays/travel times for work zones, segments, and corridors
  • Delay summaries affect scheduling and staging for major construction projects
  • During planning: Closure chart and delay estimates influence staging strategies
  • During design: Closure information used in project specifications

Slide 26. Contact Information

Irene Toews, P.E.
ODOT
Traffic Control Plans, QA Engineer
Irene.toews@odot.state.or.us
355 Capital Street NE
Salem, OR 97301
(503) 986-3595

Jeremy Jackson, E.I.T.
OBDP
Traffic Engineering Intern
jeremy.jackson@obdp.org
660 Hawthorne Ave SE, Suite 220
Salem, OR 97301
(503) 316-5519

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