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Use of Truck GPS Data for Travel Model Improvements

Use of Truck GPS Data for Travel Model Improvements. Talking Freight Seminar April 21, 2010. Truck GPS Data. 2. Presentation Overview. Vehicle Speed Comparison Grocery Store Trip Generation Discussion. Truck GPS Data. 3. Speed Differences on Freeways. Trucks Travel Slower than Cars

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Use of Truck GPS Data for Travel Model Improvements

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  1. Use of Truck GPS Data for Travel Model Improvements Talking Freight Seminar April 21, 2010

  2. Truck GPS Data 2 Presentation Overview • Vehicle Speed Comparison • Grocery Store Trip Generation • Discussion

  3. Truck GPS Data 3 Speed Differences on Freeways • Trucks Travel Slower than Cars • Acceleration • Deceleration • Speed Maintenance • Modeling Implications • Travel Demand Model • Air Quality Model • Analysis Truck Speeds Trip Generation Discussion

  4. Truck GPS Data 4 4 Motivation Continued • Truck Speeds within PSRC’s Modeling Framework • Trucks speeds are not differentiated • Overestimation of trucks on freeways • Underestimation of trucks on arterials Truck Speeds Trip Generation Discussion

  5. Truck GPS Data 5 5 GPS Data • Collected in 2003 and 2004 • Nearly ½ million observation points • From 8 trucking firms and 25 GPS units • 14 routes considered • No comparable passenger vehicle data available Truck Speeds Trip Generation Discussion

  6. Truck GPS Data 6 6 GPS Analysis Results Midday General Purpose (GP) and Truck Speeds Truck Speeds Trip Generation Discussion

  7. Truck GPS Data 7 7 Short and Long Vehicle Comparison • Data • 20-second speed trap data from the Washington State Department of Transportation • 4 vehicle length classes • Bin 1: < 26’ (short—i.e. cars) • Bins 2-4: > 26’ (long—i.e. trucks) • Only consider observations where either cars or trucks are present Truck Speeds Trip Generation Discussion

  8. Truck GPS Data 8 8 Short and Long Vehicle Analysis Comparison of Daily Average Truck GPS and Long Vehicle Speeds Truck Speeds Trip Generation Discussion

  9. Truck GPS Data 9 9 Short and Long Vehicle Analysis Weighted Average Speed Differences Truck Speeds Trip Generation Discussion

  10. Truck GPS Data 10 10 Short and Long Vehicle Analysis Comparison Over Time Truck Speeds Trip Generation Discussion

  11. Truck GPS Data 11 11 Short and Long Vehicle Analysis Speed and Car Percent at Select Locations Truck Speeds Trip Generation Discussion

  12. Truck GPS Data 12 12 In and Out Lane Comparison • Data • 5-minute speed trap data from the Washington State Department of Transportation • Innermost non-HOV lane as proxy for car speeds • Second to outermost lane as proxy for truck speeds Truck Speeds Trip Generation Discussion

  13. Truck GPS Data 13 13 In and Out Lane Analysis Weighted Average Speed Differences Truck Speeds Trip Generation Discussion

  14. Truck GPS Data 14 14 In and Out Lane Analysis Comparison Over Time Truck Speeds Trip Generation Discussion

  15. Truck GPS Data 15 15 Discussion Method Comparison Truck Speeds Trip Generation Discussion

  16. Truck GPS Data 16 16 Moving Forward • The in and out lane method yields the most promising results and is simple to implement • In 2006 trucks traveled by an average of 10% slower than cars, virtually unchanged from 2000 • Future truck model will account for 10% difference on freeways • The short and long vehicle comparison could be useful if disaggregate classification data is available • Continued need for truck count information for model validation Truck Speeds Trip Generation Discussion

  17. Truck GPS Data 17 17 GPS Based Trip Generation Data from the Washington State Department of Transportation (WSDOT) and University of Washington 2,500 trucks per day 15 minute reads > 3,000,000 records per month Examined data from Fall 2008 Geocode observation to road network Truck Speeds Trip Generation Discussion

  18. Truck GPS Data 18 18 Defining Origins and Destinations • Traffic based versus intentional stops • Use 3-minute dwell time to differentiate • One month of data: • 3,000,000 reads • 358,000 trips • 16 mile average trip distance • 21 minute average travel time • 34 miles per hour average speed Truck Speeds Trip Generation Discussion

  19. Truck GPS Data 19 19 Grocery Store Trip Generation • Truck O/D data related to grocery stores and distribution centers in the Puget Sound • Over 91 days: • 2,400 trucks • 22,000 tours • 215,000 individual trips • 9 tours per truck • 0.1 tours per day • 10 trips per tour • 2 trips to major grocer Truck Speeds Trip Generation Discussion

  20. Truck GPS Data 20 20 Validation Truck Speeds Trip Generation Discussion GPS dataset is subset of all trucks Favorable comparison to interview information (10 to 12 daily trucks) But half of observed manual counts

  21. Truck GPS Data 21 21 Daily Trips by Area Type Truck Speeds Trip Generation Discussion

  22. Truck GPS Data 22 22 Discussion Can estimate total trips by referencing truck count data disaggregated by employment sectors, land use types and times of day Average trip and tour lengths Useful for estimating and calibrating aggregate distribution models Calibrate aggregate trip generation models Speed data and route choice Potential for commodity flow model Improving quality of GPS data Truck Speeds Trip Generation Discussion

  23. Truck GPS Data 23 23 Thank You Truck Speeds Trip Generation Discussion Alon Bassok abassok@psrc.org Puget Sound Regional Council http://psrc.org/

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