1. Transportation Planning and Travel Demand Forecasting
CEE 320 Anne Goodchild

2. Outline Transportation Planning Travel Demand Forecasting Defined
Transportation Planning Organizations
Long term plan example
Short term plan example
Travel Demand Forecasting
4 step process

3. 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

4. Transportation Planning Organizations
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:

5. 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
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).

6. A Long-Term Transportation Plan
PSRC’s long-term plan:
Destination 2030
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.
Source: PSRC Website:

7. Key Messages from Destination 2030
Snohomish
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
Kitsap
King
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.
Pierce

8. 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. A Long-Term Transportation Plan
Programs:
State Ferry and Highway Programs
Local Transit
Seattle Monorail
Regional Transit
Non-motorized
Freight
Aviation
More information at:

10. A Short-Term Transportation Plan
SR 520
Freeway bottleneck
Old and at end of useful life

11. A Short-Term Transportation Plan
4-lane alternative
($ billion)
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 Lane Alternative.
6-lane alternative
($ billion)

12. A Short-Term Transportation Plan
Electronic Toll Collection
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.

13. 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

14. 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

15. Travel Demand Forecasting

16. 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. Traveler Decisions Types of decisions Influences
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. 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. 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. 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. Trip Generation An example trip generation map:
TAZ (4)
P=26,268
A=17,740
Suburbs
TAZ (5)
P=33,255
A=18,190
TAZ (2)
P=14,498
A=16,799
City
TAZ (3)
P=13,461
A=19,774
P=8,980
A=23,696
CBD
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
P = trips produced, A = trips attracted

22. 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. 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. Gravity Models Development Trail and error process TAZ (4) 1730
Suburbs
TAZ (5)
1850
TAZ (2)
1600
City
TAZ (3)
2100
1700
P=8,980
CBD

25. Trip Distribution 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

26. 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
TAZ (2)
640 bus
960 car
City
TAZ (3)
1050 bus
1050 car
1000 bus
700 car
P=8,980
CBD

27. 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)
TAZ (2)
City
TAZ (3)
CBD
8980

28. Example: Bellevue 1999-2010 Forecasted Population Growth
The legend is not recognizable, but the numbers are not important here. Basically the darker the color, the bigger the growth.
Decrease
0-99
3000+
Forecasted Population Growth
Source: Bellevue Transit Plan

29. Example: Bellevue 1999-2010 Forecasted Employment Growth
The legends are not recognizable, but the numbers are not important here. Basically the darker the color, the bigger the growth.
Decrease
0-99
3000+
Forecasted Employment Growth
Source: Bellevue Transit Plan

30. 2010 Total Bellevue Trips to Downtown and Overlake
The legends are not recognizable, but the numbers are not important here. Basically the darker the color, the bigger the growth.
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

31. 2010 Total Eastside Trips to Downtown and Overlake
Source: Bellevue Transit Plan

32. 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.