TRB Planning Applications Conference May 18, 2009 Houston, TX

1. TRB Planning Applications ConferenceMay 18, 2009Houston, TX Transportation leadership you can trust. A Recommended Approach to DelineatingTraffic Analysis Zones in Florida

2. Presentation Overview • Purpose and Need • Reviewers • Recommendation Checklist • Delineating TAZs • Base-Year Models • Future-Year TAZ Considerations • Splitting TAZs • Topics Requiring Further Research • Where to Find the Full Paper • Acknowledgements and Discussion

3. Purpose and Need • Purpose • Provide modelers within Florida guidance on delineating TAZs • Applicable both to new travel demand models and refining existing models • Need • Better represent transit access inCube Voyager’s Public Transport (PT) program • Improved model accuracy for both highwayand transit models • Consistent approach for Florida’s modeling and planning community

4. Reviewers • FDOT • Federal Highway Administration (FHWA) • Florida Model Task Force (MTF) • MTF Model Advancement Committee • MTF Data Committee • Other interested parties outside Florida

5. Recommendation Checklist • Persons per TAZ should be greater than 1,200, but less than 3,000 for all years (base and future) • Each TAZ should yield less than 15,000 person trips in all years • The size of each TAZ should be between 0.25 and one square mile in area • Achieve reasonable number of intrazonal trips in each zone based on mix and density of land use • Minimize irregular-shaped TAZs • Centroid connectors should load less than 10,000 to 15,000 vehicles per day in all years

6. Recommendation Checklist (Cont’d) • Study areas should be large enough so that nearly all (>90%) of trips begin and end within study area • The TAZ structure should be compatible with highway and transit networks for all years • The centroid connectors should represent true access points to highway network • Transit access should be realistically represented • TAZ structure should be compatible with Census, physical, political, and planning district boundaries • Special generators and freight generators should be isolated within their own TAZ

7. Delineating TAZs in the Base-Year Model Figure 3.3 Blocks versus Block Groups versus Census Tracts • Zone size and quantity • Boundary compatibility • Socioeconomic data • Access • Centroid connectors • Existing transportationfacilities • TAZ numbering

8. Delineating TAZs in the Base-Year Model Zone Size and Quantity • Size of zones depends on intended use of model • Larger-sized zones for statewide and systems planning • Statewide models • TAZs can be larger than the arterial grid • Up to approximately 20,000 persons per zone • Medium-sized zones for major investment planning • Regional or MPO models • Two or more arterials should not traverse the TAZ in any direction • Up to approximately 4,000 persons per zone • Small-sized zones for corridor analysis • Corridor level or subarea models • TAZs in a corridor or subarea should be more refined • Should be greater than 1,200, but less than 3,000persons per zone

9. Delineating TAZs in the Base-Year Model Boundary Compatibility Figure 3.1 Delineating TAZs Consistent with the Physical Geography • Physical geography • Census geography • Political geography • Planning district/sector boundaries • Irregular zone geography Figure 3.2 Delineating TAZs Based on Permanent Barriers

10. Delineating TAZs in the Base-Year Model Socioeconomic Data Figure 3.10 Delineating TAZs Based on Clusters of Similar Land Uses • Special generators • Trips per zone • Developments ofregional impact

11. Delineating TAZs in the Base-Year Model Access Figure 3.11 Over-Estimating Walk Access to Transit • Transit access • Freight/intermodal facilities

12. Delineating TAZs in the Base-Year Model Centroid Connectors • Represent realistic roadway and transit access • Should not cross man-made or natural barriers • Include sufficient number of centroid connectors to avoid over-loading to one roadway network link • Do not connect centroid connectors at intersectionsor directly to interstate ramps • When two centroid connectors are connected to the same roadway segment, access points should be separated by a certain distance The Wrong Way The Right Way Figure 3.20 Placement of Centroid Connectors Relative to Intersectionsand Interstate Ramps

13. Delineating TAZs in the Base-Year Model Existing Transportation Facilities Figure 3.14 Delineating TAZs Based on Transit Access • Rail lines • Limited access highways • Arterial streets and roadways • Collector streets and roadways

14. Delineating TAZs in the Base-Year Model TAZ Numbering • Recommended that TAZ numbers begin with oneand be consecutive • Regional models may set aside a specific range of TAZ numbers for both TAZs and dummy zones for each county • Create TAZ equivalency tables to provide list of new zone numbers split from original zone numbers

15. Future Year TAZ Considerations Figure 4.1 Defining the TAZ Structure Based on Future Corridors • Plannedtransportationcorridors • Developments ofregional impact • Populationand tripsper zone Figure 4.2 Defining the TAZ Structure Based on Future DRI

16. Future Year TAZ ConsiderationsPopulation and Trips per Zone • Greater than 15,000 trips per day or 1,200 to 3,000 people per TAZ exceeds recommended zone size • The Census Bureau is currently considering increasing the minimum number of persons per block group (and potentially TAZs) to 1,200 persons (previously 600) or 480 households. The existing maximum thresholds of 3,000 persons and 1,200 households per block group remain unchanged • Often times, a TAZ may not have as many people or generate that many daily trips in the base-year • However, with future-year land use, it may push population or daily trips over the thresholds noted above

17. Splitting TAZs • Network data impacts • Socioeconomicdata impacts • Boundary shiftsand zone aggregations • Zones beyondmodel boundary • Revalidation Figure 5.1 Splitting Household Data into New TAZs

18. Topics Requiring Further Research • Mixed land uses • Delineating TAZs based on homogenous land uses is notalways feasible • CBDs and neo-traditional developments make it difficult to isolate employees from households • Dynamic subzoning • Potential solution to mixed land use issue • Includes multiple centroids within one zone; one to represent employment and another to represent households • Allows different access points onto the network by having one set of centroid connectors for employment and another for households • Would require further research, including the numberingof subzones

19. Where to Find the Paper • Full White Paper is on-line at www.fsutmsonline.net

20. Acknowledgements • Florida Department of Transportation (FDOT) • Vidya Mysore, Systems Planning Office (SPO) • Terry Corkery, SPO • Cambridge Systematics (CS) • Keli Paul, AICP • Rob Schiffer, AICP • AECOM Consult • Dave Schmitt

21. Questions or Comments? Discussion Keli Paul, AICP Cambridge Systematics Senior Associate Tallahassee, FL 32301 850.219.6388 kpaul@camsys.com Terry Corkery FDOT, Systems Planning Office Senior Transportation Modeler Tallahassee, FL 32399 850.414.4900 Terrence.Corkery@dot.state.fl.us