Case Studies of Truck Activity Data for Emissions Modeling (2019) / Chapter Skim
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From page 71... ...
Guide to Truck Activity Data for Emissions Modeling C-1 Appendix C Case Study #3: Truck Starts and Soak Time from GPS Data C.1 Emissions Model Inputs Supported • Starts per vehicle (by source type, hour of day, and weekday/weekend)
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Guide to Truck Activity Data for Emissions Modeling C-2 C.4 Data Sources Data Source Source Agency/Organization Availability and Cost Trip data compiled and aggregated from GPS devices (primarily commercial fleet management systems for trucks) StreetLight Data, Inc.
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Guide to Truck Activity Data for Emissions Modeling C-3 Figure C.1 Trip Metric Definitions and Example The case study focused on three counties: Denver (Colorado) , Fairfax (Virginia)
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Guide to Truck Activity Data for Emissions Modeling C-4 StreetLight MD data to 52 and 53s, and StreetLight HD to 61 and 62s, the start/vehicle data could be imported directly into StartsPerVehicle. This table is not listed under the "Starts" tab of the County Data Manager, but can be accessed through the "Generic" tab, and read into a custom database specified by the user.
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Guide to Truck Activity Data for Emissions Modeling C-5 Figure C.2 StreetLight Starts per Truck by County/Class/Day Type: Medium Trucks Figure C.3 StreetLight Starts per Truck by County/Class/Day Type: Heavy Trucks 0 0.05 0.1 0.15 0.2 0.25 0.3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour of Day Starts Per Truck per Hour D/M/Wd D/M/We F/M/Wd F/M/We N/M/Wd N/M/We 0 0.2 0.4 0.6 0.8 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour of Day Starts Per Truck per Hour D/H/Wd D/H/We F/H/Wd F/H/We N/H/Wd N/H/We
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Guide to Truck Activity Data for Emissions Modeling C-6 The corresponding MOVES defaults for starts/truck are shown in Figure C.4 and Figure C.5. Source Type 52 and 53 (Figure C.4)
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Guide to Truck Activity Data for Emissions Modeling C-7 Figure C.5 MOVES Default Starts per Truck: Combination Trucks Figure C.6 shows average dwell (soak) times for MD trucks.
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Guide to Truck Activity Data for Emissions Modeling C-8 Figure C.6 StreetLight Average Dwell (Soak) Time by County/Day Type Medium Duty Figure C.7 StreetLight Average Dwell (Soak)
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Guide to Truck Activity Data for Emissions Modeling C-9 Similar to the StreetLight data, MOVES default soak times will mirror the default starts/vehicle shown in Figure C.4 and Figure C.5; when starts/vehicle increase, average soak time decreases. The comparisons of starts/vehicle summarized above will also be mirrored in the comparison of soak times.
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Guide to Truck Activity Data for Emissions Modeling C-10 Figure C.9 StreetLight Denver Weekday Operating Mode (Soak Time) Distribution Medium and Heavy Trucks C.6.2 Emissions Sensitivity Results To evaluate emissions sensitivity to the new start activity data, MOVES was run for Denver County with default inputs, and with StreetLight data (specifying 8101_altstartspervehicle_denver_in in Manage Input Datasets screen)
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Guide to Truck Activity Data for Emissions Modeling C-11 Figure C.10 Baseline Denver County Emissions by Truck Source Type Tons per Day Figure C.11 shows the percent change in emissions (start only, and total) when only the StreetLight starts per vehicle are run (with default soak times)
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Guide to Truck Activity Data for Emissions Modeling C-12 Figure C.11 Total Change in Denver County MD/HD Emissions Using StreetLight Data versus Default Hourly differences are also important. Figure C.12 shows the change in start emissions by hour for HC and CO (the most consequential pollutants for start emissions)
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Guide to Truck Activity Data for Emissions Modeling C-13 • A challenge that will be encountered with any dataset is defining a vehicle "population" (for the denominator of the starts/vehicle metric) comparable to the MOVES definition.
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