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Urban Freight Data Collection 1 Jeffrey Wojtowicz wojtoj@rpi.edu VREF Center of Excellence for Sustainable Urban Freight Systems
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Introduction The development of freight demand models is difficult due to: Lack of proper balance: knowledge, models and data Poorly understood system Complexity of the freight system: Multiple interacting agents with partial views Multiple metrics to measure freight Links between participants Functions performed Modes/vehicles used Levels of geography 2
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Partial view of the freight system 3 Notes: (1): Only of the cargo that they handle. (2): For all the cargo they receive. No single agent can provide a complete picture of the system
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Multiplicity of metrics 4 Base 1 2 3 4 5 Loaded vehicle-trip Commodity flow Notation: Consumer of cargo (receiver) Empty vehicle-trip
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Data Needs and Sources
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Data required by modeling techniques 6
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Data sources Primary data sources (in the USA) Commodity flow survey (CFS) data Zip code business patterns (ZCBP) Surveys + interviews + travel diaries … Secondary sources GPS data Experts Data and Freight Demand Synthesis Fill in gaps, could provide good estimates Reduce data collection costs but may introduce an error 7
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Data gaps identified (United States) 8 Most data needed must be collected from scratch
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Data collection Types of data collection techniques or surveys depend on how the sampling frame is defined: Establishments at origin or destination of the shipment Truck traffic Delivery tour Shipment This leads to data collection methods that focus on: Origin or destination of the cargo En-route, as in a truck intercept survey Along the supply chain 9
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Surveys Data collection methodologies vs. sampling frame: Establishment-based surveys Shipper, receiver, and carrier based Trip intercept based surveys Roadside interviews Vehicle based surveys Travel diaries, and surveys assisted by GPS Tour based surveys Longitudinal surveys Freight volumes data collection techniques 10
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GPS and freight data collection Global Positioning Systems track routing patterns Spatial and temporal Cannot provide data collected by traditional surveys e.g., commodity type, shipment size, trip purpose Need other data sources/methods Good complement to more traditional freight data collection procedures Commercially available GPS data are likely to be biased and difficult convert into a representative sample 11
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Advantage: Engine status (Ignition off, Ignition On) and travel status (start, stop) Assumption: Apart from warehouse and truck centers, a vehicle will only turn the engine off for deliveries at stores. This helps identify delivery stops. Event Based GPS Data 12 LabelDate / TimeAddressLatitudeLongitudeEvent 9284/3/2012 21:50521 Park Ave, New York, NY, 1006540.763525-73.9692138Travel Stop 9284/3/2012 21:501 Central Park S, New York, NY, 1001940.76478-73.9737944Travel Start 9284/3/2012 21:55937 7th Ave, New York, NY, 1001940.76668-73.9790527Drive 9284/3/2012 22:0098 W 53rd St, New York, NY, 1001940.761666-73.9790111Drive 9284/3/2012 22:0365 W 56th St, New York, NY, 1001940.763447-73.9769638Travel Stop 9284/3/2012 22:0465 W 56th St, New York, NY, 1001940.763447-73.9769638Ignition Off 9284/3/2012 22:0470 W 57th St, New York, NY, 1001940.763825-73.9768972Ignition On 9284/3/2012 22:0668 W 55th St, New York, NY, 1001940.762497-73.9772Travel Start 9284/3/2012 22:0862 W 57th St, New York, NY, 1001940.763788-73.9768055Travel Stop 9284/3/2012 22:0847 W 56th St, New York, NY, 1001940.763569-73.9765194Ignition Off 9284/3/2012 22:3442 W 56th St, New York, NY, 1001940.762877-73.9767305Ignition On
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Sample GPS route data 13
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Sample GPS data 14
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Sample analysis from GPS data 15
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Sampling frames and data 16
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Summary There is no magic answer for getting freight data Relationships must be cultivated Patience must be practiced Asking for too much data can be a disadvantage Request needs to be defensible Generally willing to collaborate if requests are within reason 17
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Thank you! Questions? 18 Jeffrey Wojtowicz Sr. Research Engineer Assistant Director of Administration VREF CoE-SUFS Rensselaer Polytechnic Institute Troy, NY 12180 wojtoj@rpi.edu
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