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

22 Presentation Overview Truck GPS Data Vehicle Speed Comparison Grocery Store Trip Generation Discussion

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

44 Motivation Continued Truck GPS Data Truck Speeds within PSRC’s Modeling Framework Trucks speeds are not differentiated Overestimation of trucks on freeways Underestimation of trucks on arterials Facility TypeCountVolumeLocationsDifference Percent Difference Freeways 552, , ,71474% Arterials 679, , (411,585)-61% Total 1,231,767 1,227, (3,871)0% Truck Speeds Trip Generation Discussion

55 GPS Data Truck 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

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

77 Short and Long Vehicle Comparison Truck GPS Data 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

88 Short and Long Vehicle Analysis Truck GPS Data Comparison of Daily Average Truck GPS and Long Vehicle Speeds GPSLong Vehicles SpeedObservationsSpeedObservations Truck Speeds Trip Generation Discussion

99 Short and Long Vehicle Analysis Truck GPS Data TimeShortLong Difference Percent Difference AM Peak % PM Peak % Weighted Average Speed Differences Truck Speeds Trip Generation Discussion

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

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

12 In and Out Lane Comparison Truck GPS Data 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 In and Out Lane Analysis Truck GPS Data TimeShortLong Difference Percent Difference AM Peak % PM Peak % Weighted Average Speed Differences Truck Speeds Trip Generation Discussion

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

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

16 Moving Forward Truck GPS Data 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 GPS Based Trip Generation Truck GPS Data Truck Speeds Trip Generation Discussion 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

18 Defining Origins and Destinations Truck GPS Data Truck Speeds Trip Generation Discussion 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

19 Grocery Store Trip Generation Truck GPS Data Truck Speeds Trip Generation Discussion 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

20 Validation Truck GPS Data 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 Daily Trips by Area Type Truck GPS Data Truck Speeds Trip Generation Discussion Land UseDaily Trucks Metropolitan Cities12.4 Core Cities12.1 Larger Cities8.4 Smaller Cities6.6 Unincorporated Urban Areas7.3 Rural3.9

22 Discussion Truck GPS Data Truck Speeds Trip Generation 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

23 Thank You Truck GPS Data Alon Bassok Puget Sound Regional Council Truck Speeds Trip Generation Discussion