Transportation Planning & Travel Demand Forecasting (Transportation Engineering)
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This document provides an overview of transportation planning and travel demand forecasting. It discusses long-term and short-term transportation planning, including examples. It also explains the four-step travel demand forecasting process of trip generation, trip distribution, mode split, and trip assignment. Key models used include Poisson models for trip generation, gravity models for trip distribution, and logit models for mode split.
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Transportation Planning & Travel Demand Forecasting (Transportation Engineering)
- 1. CEE320 Winter2006 Transportation Planning and Travel Demand Forecasting CEE 320 Steve Muench
- 2. CEE320 Winter2006 Outline 1. Transportation Planning – Defined – Transportation Planning Organizations – Long term plan example – Short term plan example 2. Travel Demand Forecasting – 4 step process
- 3. CEE320 Winter2006 Transportation Planning • Transportation planning – The process to provide the information needed for decision makers to choose among alternative strategies for improving transportation system performance. • Transportation planning is future-oriented – Uncertainty in predictions – Balance short-term and long-term benefits • The problem is not isolated and independent – Hierarchical structure – Broad impact and involvements
- 5. CEE320 Winter2006 Transportation Planning Long term (strategic) planning – Very complex – Based on long-term predictions – Involves multiple levels of government and administration • Short to medium term planning – Less complex – Reduced uncertainty – More specific
- 6. CEE320 Winter2006 A Long-Term Transportation Plan Source: PSRC Website: http://www.psrc.org/projects/mtp/index.htm • PSRC’s long-term plan: – Destination 2030
- 7. Key Messages from Destination 2030 • Puget Sound is a Growing Region • We Have a Balanced Plan • Linking Land Use and Transportation • Investment and Finance Principles • Monitoring Performance DESTINATION 2030 Snohomish Kitsap King Pierce
- 8. CEE320 Winter2006 A Long-Term Transportation Plan • Destination 2030 is comprehensive: – Identifies over 2,200 specific projects that have been designed to result in improved roads, transit, and ferry service. – Over 2000 miles of new and improved regional state roadways. – More than 2000 miles of new walkways and bikeways to connect communities with transit, shopping, and services. – Incentives to better transit service, carpools, etc.
- 9. CEE320 Winter2006 A Long-Term Transportation Plan • Programs: – State Ferry and Highway Programs – Local Transit – Seattle Monorail – Regional Transit – Non-motorized – Freight – Aviation More information at:http://www.psrc.org/projects/mtp/d2030plan.htm
- 10. CEE320 Winter2006 A Short-Term Transportation Plan • SR 520 – Freeway bottleneck – Old and at end of useful life
- 11. CEE320 Winter2006 A Short-Term Transportation Plan 4-lane alternative ($1.7-2.0 billion) 6-lane alternative ($2.6-2.9 billion)
- 12. CEE320 Winter2006 A Short-Term Transportation Plan Electronic Toll Collection
- 13. CEE320 Winter2006 Basic Elements Transportation System DB Socioeconomic and land use DB Goals and Objectives Identify Deficiencies and Opportunities Develop and Analyze Alternatives Evaluate Alternatives Implement Plan Goals and Objectives
- 14. CEE320 Winter2006 Planning Realities • Uncertainty in predicting the future – Economy, fuel, population growth • Analytical limitations – Inventory, forecasting, performance measures • Influence of politics – MPO is an explicitly political forum – In a democracy, elected officials should make key decisions
- 16. CEE320 Winter2006 Need for Travel Demand Forecasting • Impacts of facilities or modes of travel – Lines on existing roads – Roads – Light rail – Bus service • Geometric design • Pavement design
- 17. CEE320 Winter2006 Traveler Decisions • Types of decisions – Time (when do you go?) – Destination (where do you go?) – Mode (how do you get there?) – Route choice (what route do you choose?) • Influences – Economic – Social
- 18. CEE320 Winter2006 Predicting Travel Decisions • Collect data on travel behavior – Observation (number of buses, cars, bikes, etc.) – Surveys • Collect data on what travelers have done • Collect data on their values and choices (utility) • Inexact nature of prediction – Incomplete data – Reporting problems
- 19. CEE320 Winter2006 Travel Demand Forecasting • Divide process into 4 steps: – Trip Generation – Trip Distribution – Mode Split – Trip Assignment • We will explore further: – Trip generation Poisson models – Mode choice logit models – Trip assignment route choice models
- 20. CEE320 Winter2006 Trip Generation • Relates the number of trips being produced from a zone or site by time period to the land use and demographic characteristics found at that location. • Assumptions: – Trip-making is a function of land use – Trips are made for specific purposes – Different trip types are made at different times of the day – Travelers have options available to them – Trips are made to minimize inconvenience – System modeling is based on Traffic Analysis Zones and networks • Poisson model often used
- 21. CEE320 Winter2006 Trip Generation TAZ (4) P=26,268 A=17,740 Suburbs TAZ (5) P=33,255 A=18,190 Suburbs TAZ (2) P=14,498 A=16,799 City TAZ (3) P=13,461 A=19,774 City TAZ (5) P=8,980 A=23,696 CBD P = trips produced, A = trips attracted An example trip generation map:
- 22. CEE320 Winter2006 Trip Distribution • Connect trip origins and destinations estimated by the trip generation models • Different trip distribution models are developed for each of the trip purposes for which trip generation has been estimated • Most common model in practice is the "gravity model"
- 23. CEE320 Winter2006 Gravity Models • Distribution of trips is: – Proportional to the number of trips produced and attracted by each zone – Inversely proportional to the separation between the origin and destination zones • Widespread use because of its simplicity, its reasonable accuracy and support from the USDOT
- 24. CEE320 Winter2006 Gravity Models • Development – Trail and error process TAZ (4) 1730 Suburbs TAZ (5) 1850 Suburbs TAZ (2) 1600 City TAZ (3) 2100 City TAZ (5) 1700 P=8,980 CBD
- 25. CEE320 Winter2006 Trip Distribution = ∑zonesall ijijj ijijj iij KFA KFA PT Tij = Number of trips produced in zone i and attracted to zone j Pi = Number of trips produced by zone i Aj = number of trips attracted by zone j Fij = friction factor (the gravity part) c is often 1 and n is often 2 t = travel time Kij = socio economic adjustment (fudge) factor nij t c F =
- 26. CEE320 Winter2006 Mode Split • Based on utility (level of attractiveness) of modes • Logit model most commonly used TAZ (4) 577 bus 1153 car Suburbs TAZ (5) 462 bus 1388 car Suburbs TAZ (2) 640 bus 960 car City TAZ (3) 1050 bus 1050 car City TAZ (5) 1000 bus 700 car P=8,980 CBD
- 27. CEE320 Winter2006 Trip Assignment • Assigns trips to paths through the network • Two most common methods – All or nothing (shortest path) assignment – Capacity restraint (incremental) assignment TAZ (4) Suburbs TAZ (5) Suburbs TAZ (2) City TAZ (3) City TAZ (5) CBD 8980
- 28. CEE320 Winter2006 Example: Bellevue 1999-2010 Forecasted Population Growth Source: Bellevue Transit Plan 2001-2007 Decrease 0-99 100-499 500-999 1000-2999 3000+
- 29. CEE320 Winter2006 Example: Bellevue 1999-2010 Forecasted Employment Growth Source: Bellevue Transit Plan 2001-2007 Decrease 0-99 100-499 500-999 1000-2999 3000+
- 30. CEE320 Winter2006 5,000 trips 10,000 trips 15,000 trips 20,000 trips 25,000 trips 2010 Total Bellevue Trips to Downtown and Overlake Source: Bellevue Transit Plan 2001-2007
- 31. CEE320 Winter2006 5,000 trips 10,000 trips 15,000 trips 20,000 trips 25,000 trips 30,000 trips 2010 Total Eastside Trips to Downtown and Overlake Source: Bellevue Transit Plan 2001-2007
- 32. CEE320 Winter2006 Primary References • Mannering, F.L.; Kilareski, W.P. and Washburn, S.S. (2003). Principles of Highway Engineering and Traffic Analysis, Third Editio. Chapter 8 • Transportation Engineering Online Lab Manual (2000). Oregon State University, Portland State University, Idaho University. http://www.webs1.uidaho.edu/niatt_labmanual/index.htm
Editor's Notes
- Federal transportation legislation requires that a Metropolitan Planning Organization (MPO) be designated for each urbanized area with a population of more than 50,000 people in order to carry out the metropolitan transportation planning process, as a condition of Federal aid. In 1990, the Washington State Legislature passed the Growth Management Act (ESHB 2929) authorizing the Regional Transporaton Planning Program. This program allows for the formation of Regional Transportation Planning Organizations (RTPOs). The primary functions of RTPOs are to develop regional plans and policies for transportation, growth management, environmental quality, and other topics determined by the RTPO; provide data and analysis to support local and regional decision making; build community consensus on regional issues through information and citizen involvement; build intergovernmental consensus on regional plans, policies and issues, and advocate local implementation; and provide planning and technical services on a contractual basis. --source: http://www.wsdot.wa.gov/ppsc/planning/WhatRTPO.htm
- Short term plan tends to place no great demands on construction activities and therefore has no large capital requirements. The scale of the problem usually is quite limited and the analysis and evaluation, while being detailed, are usually simple in structure. This type of problem comes under the generic term Transportation systems management (TSM).
- The Puget Sound Regional Council is an association of cities, towns, counties, ports, and state agencies that serves as a forum for developing policies and making decisions about regional growth and transportation issues in the four-county (Pierce, King, Snohomish and Kitsap) central Puget Sound region What is a Highway of Statewide Significance? The Revised Code of Washington (RCW) sets minimal criteria for HSS designation: “This statewide system shall include at a minimum interstate highways and other statewide principal arterials that are needed to connect major communities across the state and support the state’s economy.” The Washington State Transportation Commission expanded the criteria, an HSS roadway must also be: A State Highway; A Principal Arterial that is part of the National Highway System (NHS); Rural routes serving statewide travel; and/or Urban routes that are: Statewide travel links to Rural HSS, Connections to Principal Arterial Ferry Routes, Long haul freight links - FGTS Class T1 and T2, and Connections to ports - FGTS Class T1 and T2. Designation of a route as HSS means: Higher priority for improvement funding; State has authority for setting level-of-service (LOS); Highway segment is exempt from local transportation concurrency requirements; Identified as an essential public facility; Consideration for primary funding by a the RTID.
- <number> Our region’s growth is constrained by water on one side, mountains on the other, and things like wetlands and earthquake fault lines in between. Transportation answers aren’t simple or cheap. Custom fit: The beauty of Destination 2030 is it’s custom fit to our region – not just our topography but our cities, towns and neighborhoods. So in the end we can grow but still maintain our natural environment and quality of life.
- The WSDOT team studied potential I-5 improvements to accommodate SR 520 traffic from the 8-Lane Alternative through downtown Seattle. Project investigations found that I-5, already over capacity, would be unable to handle traffic from the 8-Lane Alternative without considerable improvements. The 8-Lane Alternative will be in the SR 520 Bridge Replacement and HOV Project Draft EIS as a traffic/engineering appendix. Further environmental analysis of the 8-Lane Alternative will not be included in the Draft EIS. The 8-Lane Alternative may be further evaluated if the I-5 study identifies operational improvements on I-5 that would accommodate the SR 520 8-Lane Alternative.
- WSDOT is assuming tolls to be a future means of funding the project. The Regional Transportation Investment District (RTID) - made up of King, Pierce and Snohomish counties - is also developing a potential long-term funding package for approval by the voters.
- Trip productions and attractions are computed for each zone by land use Trip Purposes HBW – Home based work trip HBNW – Home based nonwork trip NHB – Non-home based trip Usually computed using trip generation rates
- The legend is not recognizable, but the numbers are not important here. Basically the darker the color, the bigger the growth.
- The legends are not recognizable, but the numbers are not important here. Basically the darker the color, the bigger the growth.
- The legends are not recognizable, but the numbers are not important here. Basically the darker the color, the bigger the growth.