Case Studies of Truck Activity Data for Emissions Modeling (2019) / Chapter Skim
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From page 105... ...
Guide to Truck Activity Data for Emissions Modeling E-1 Appendix E Case Study #5: Speed Distributions from the National Performance Management Research Data Set E.1 Emissions Model Inputs Supported • Average speed distribution.
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From page 106... ...
Guide to Truck Activity Data for Emissions Modeling E-2 E.3.1 MOVES Approach to Speed Distributions The average speed distribution for county-scale MOVES analysis is a set of 16 fractions that sum to 1, which represents the distribution of vehicle-hours traveled among 16 speed bins. MOVES requires this information for every combination of 13 source (vehicle)
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From page 107... ...
Guide to Truck Activity Data for Emissions Modeling E-3 information from the Highway Performance Monitoring System and volume information from the Traffic Management Analysis System, both of which are maintained by FHWA. The approach to processing NPMRDS data, as outlined in the VDOT memo (which also gives screenshots of data tables)
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From page 108... ...
Guide to Truck Activity Data for Emissions Modeling E-4 • Pollutants: PM2.5, NOX and associated processes. • Source types: 52, 53, 61, 62 (the VDOT analysis also examined source type 21, passe)
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From page 109... ...
Guide to Truck Activity Data for Emissions Modeling E-5 Figure E.1 Rural Restricted Access Speed Distribution Virginia Figure E.2 Rural Unrestricted Access Speed Distribution Virginia 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 2.5 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Fraction Speed Bin (mph) NPMRDS Truck Default Single-Unit Truck Default Combination Truck 0 0.05 0.1 0.15 0.2 0.25 0.3 2.5 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Fraction Speed Bin (mph)
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Guide to Truck Activity Data for Emissions Modeling E-6 Figure E.3 Urban Restricted Access Speed Distribution Virginia Figure E.4 Urban Unrestricted Access Speed Distribution Virginia 0 0.1 0.2 0.3 0.4 0.5 0.6 2.5 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Fraction Speed Bin (mph) NPMRDS Truck Default Single-Unit Truck Default Combination Truck 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 2.5 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Fraction Speed Bin (mph)
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From page 111... ...
Guide to Truck Activity Data for Emissions Modeling E-7 Observations include: • For both rural restricted and unrestricted access roads, the NPMRDS truck and auto speed distributions peak at lower speeds than the MOVES defaults. • For urban unrestricted access roads, the default distributions are flatter with higher fractions of VMT occurring in the lowest speed bins compared to the NPMRDS distributions.
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From page 112... ...
Guide to Truck Activity Data for Emissions Modeling E-8 Figure E.5 Combination Truck NOx Emissions (g/mi) Figure E.6 Single-Unit Truck NOx Emissions (g/mi)
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From page 113... ...
Guide to Truck Activity Data for Emissions Modeling E-9 Figure E.7 Combination Truck PM2.5 Emissions (g/mi) Figure E.8 Single-Unit Truck PM2.5 Emissions (g/mi)
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From page 114... ...
Guide to Truck Activity Data for Emissions Modeling E-10 Observations include: • The largest differences in grams per mile emission rates between the NPMRDS and defaults occurred on the urban unrestricted access roads. Truck NOx emissions were 14 – 22 percent lower for NPMRDS speed distributions than for default speed distributions.
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From page 115... ...
G uide to Truck A ctivity D ata for E m issions M odeling E-11 Figure E.9 Auto and Truck Speed Distributions from VDOT NPMRDS Data 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Speed range (mph) Speed Distribution, Rural Restricted auto_vht% truck_vht% 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Speed range (mph)
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