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Statewide Modeling and Corridor Management

Statewide Modeling and Corridor Management. CE 451/551. A good reference: http://onlinepubs.trb.org/onlinepubs/circulars/ec011/ec011.pdf. Statewide Models Managing Access in Commuting Corridors. Presentation Outline. What is a Statewide Model?.

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Statewide Modeling and Corridor Management

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  1. Statewide Modeling and Corridor Management CE 451/551 A good reference: http://onlinepubs.trb.org/onlinepubs/circulars/ec011/ec011.pdf

  2. Statewide Models Managing Access in Commuting Corridors Presentation Outline

  3. What is a Statewide Model? • Very similar to a Metropolitan Area Travel Demand Model. Wider in scope! • Many use the same sequential 4-Step Process • Trip Generation • Mode Split • Trip Distribution • Traffic Assignment • Truck Model • Freight Model • Intercity Bus • Air and Barge

  4. Why Model Statewide? • We are seeing the benefits modeling brings to urban areas. • Technical basis behind big $ projects. • In the rural area there is no such technical tool to support decision making. • Currently use old fashioned hand-drawn methods to forecast traffic.

  5. Why Model Statewide? • Traffic forecasts affect every aspect of a State DOT’s core business activities. • Planning, finance, programming, design, construction and maintenance. • A useful, cost-effective tool • System, corridor, project level analysis for evaluating needs and alternatives • Consistent methodology • Better than current DOT method. Two forecasters-two forecasts.

  6. Why Model Statewide? • Policy questions • State Gas Tax Increase • Project Prioritization • Statewide VMT by geographic area to determine where dollars should be spent • State Plan (like MPO Plan) • Bypass Studies • Corridor Studies • Rural detour studies

  7. Why Model Statewide? • One major construction project costs millions of dollars. Shouldn’t it be based on the best available data?

  8. Project Example • US 218 – Charles City, Iowa Area. • Avenue of the Saints. • St. Louis, Missouri and St. Paul, Minnesota • Systems Planning did a traffic forecast for pavement design. • Old fashioned trend line growth analysis. • We totally missed on the Truck percentages. • Route experienced significant increases in truck volumes.

  9. Maps from www.iowadotmaps.com

  10. Project Example • What happened? • Asphalt pavement mix substandard for those truck weights. • Result: Significant rutting. • Too many dynamics taking place. • Statewide Model likely benefit. • Could have saved a lot of $.

  11. Truck trends Percentage of Segments with Over 10,000 Trucks, Comparison of 1998 to 2020.

  12. National Trend

  13. Opportunity for Modelers • Large Scale Plans require Huge Investments • Need Computer Models to Help Decisions • Statewide Model new in Iowa - MI had one in the 1960s see: http://onlinepubs.trb.org/onlinepubs/circulars/EC011/NELLET.PDF • Built from Urban Knowledge Base • Severely Lacking Intercity Data • Lacking in Data Overall • Survey Data

  14. Data Collection is Key • Data or Theory? Shortcomings in Both • Behavioral Surveys are needed • Origin Destination Surveys are needed • Focused to Specific Corridors • Economic Interaction Surveys • Commodity Flow Surveys

  15. Louisiana Maine Virginia Texas Michigan Ohio Wisconsin Florida California New Hampshire North Carolina South Carolina Oregon Mississippi Vermont Missouri Kentucky Now Iowa Other States

  16. Statewide Modeling Capabilities • Passenger Car Models • Truck Models • Freight Models • Rail Models • Intercity Bus • Air • Barge • Intermodal Connections • Time of Day • Trip Purpose

  17. Ohio Example

  18. Nationwide Coverage

  19. Coded Area Type

  20. Virginia Example County Level Zones

  21. Virginia Example County Level Zones to Larger Areas

  22. Virginia Example Network Why is this road needed?

  23. Kentucky Zone Example

  24. Kentucky Zone Example Iowa’s Model will simulate this structure. BEA Business Economic Areas

  25. Trip Generation Data • Population • Employment • CTPP • National Survey Data • Reebie Data (now Global Insight): Transsearch database

  26. Trip Purposes • Home Based Work • Home Based Non-Work • Urban Non-Home Based (2,500 +) • Rural Non-Home Based • Tourist • Truck and External Trips

  27. Special Generators • Intermodal Centers • Tourist Attractions • Etc.

  28. Trip Distribution • Even though there are issues the Gravity Model is the common choice • Issue – Rural vs Urban Trip Lengths • Trip Distances are Different • Why we have both urban and rural trip purposes

  29. Trip Assignment • All or Nothing • Capacity Restraint – Traditional • Pre-Assignment of Trucks • Ensures trucks stay on through routes • Don’t use Equilibrium Assignment

  30. Calibration vs Validation • No Widely Accepted Standards • Lenient FHWA standards apply. • +/- 4,000 ADT

  31. Typical Cost and Time • Depends on Multimodal Detail • Depends on Data Available • Are Travel Surveys Needed? • Range to Expect $300,000 - $2 million • Or $6 million for Activity Based like Ohio • Typically, a multi-year effort

  32. Process to Identify High Priority Corridors for Access Management Near Large Urban Areas in Iowa David Plazak and Reg Souleyrette Center for Transportation Research and Education Iowa State University

  33. Rating Description 1 Access points at interchanges only 2 Access points spaced at minimum 2625 ft 3 Access points spaced at minimum 984 ft rural, 656 ft urban 4 Access points spaced at minimum 656 ft rural, 328 ft urban 5 Iowa DOT has minimum access rights acquired 6 Iowa DOT has no access rights acquired Source: Iowa DOT. Iowa DOT Access Priority Ratings (English Conversion)

  34. Research Project Goals • Address current and future access management problems • on state highway routes • located just outside urban areas • that serve as major routes for commuting • There were two basic goals for the project: • Develop a ranking system for identifying high-priority segments for access management treatments on primary highways outside metro and urban areas. • Focus efforts on routes that are major commuting routes at present and in the future • An example commuting corridor: US 6 to the west of the Des Moines metropolitan area (on next slide)

  35. US 6, In The Waukee Area

  36. Technologies Used • Arc View GIS was used to integrate various Iowa DOT databases, including roadway characteristics, traffic, and crash records • A 2940 zone traffic model was developed to estimate and forecast commuting activity on all Primary routes  • Known model weakness: border metro areas  

  37. Iowa Forecast Population Growth By County Source: Woods and Poole Economics

  38. Traffic Model Zone Structure Traffic Analysis Zones (TAZs) were developed from US Census Block Groups.

  39. ArcView was used to find the center of each TAZ and then create a centroid at this location • The centroids were then connected to the network at breaks in the existing network

  40. To reduce the number of segments and nodes between intersections, ArcInfo was used to combine multiple segments into a single link ArcView was then used to create node and link files formatted for use in TRANPLAN

  41. Base-year Estimated Traffic Model Commuting Trip Volume

  42. 5-Year Estimated Traffic Model Commuting Trip Volume

  43. Forecast Absolute Change In Commuting, 1999-2004

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