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From page 34... ... 34 6.1 Overview MOVES uses data regarding the number of starts by time of day and the distribution of soak times in the estimation of engine start emissions and evaporative fuel vapor losses (soak time is defined as the length of time the vehicle engine remained off prior to being started) Read the entire page →
From page 35... ... Starts and Soak Times 35 Nominal Soak Period (Minutes) opMode ID Definition 3 101 Soak Time < 6 minutes 18 102 6 minutes ≤ Soak Time < 30 minutes 45 103 30 minutes ≤ Soak Time < 60 minutes 75 104 60 minutes ≤ Soak Time < 90 minutes 105 105 90 minutes ≤ Soak Time < 120 minutes 240 106 120 minutes ≤ Soak Time < 360 minutes 540 107 360 minutes ≤ Soak Time < 720 minutes 720 108 720 minutes ≤ Soak Time Source: U.S. Read the entire page →
From page 36... ... 36 Guide to Truck Activity Data for Emissions Modeling be entered via the StartsPerVehicle table in the Generic Importer, which was the approach used for Case Study #3 (see Appendix C, available in NCHRP Web-Only Document 261) Read the entire page →
From page 37... ... Starts and Soak Times 37 supply custom OMDs that override these defaults by populating the ImportStartOpMode Distribution table via the Starts tab of the Data Importer; the structure of this table is shown in Table 6.10. The OpModeIDs correspond to bins that correspond to a range of time periods preceding starts -- from a period of 0 to 6 minutes (hot start) Read the entire page →
From page 38... ... 38 Guide to Truck Activity Data for Emissions Modeling data in this table are used as the basis for number of vehicle starts (based on source type population) and source hours parked (SHP) Read the entire page →
From page 39... ... Starts and Soak Times 39 6.4 Generating Local Data Options for generating local data on truck start patterns may include • Conducting field surveys (instrumented vehicles) with portable data loggers. Read the entire page →
From page 40... ... 40 Guide to Truck Activity Data for Emissions Modeling et al., 2017; Kotz et al., 2018) Read the entire page →
From page 41... ... Starts and Soak Times 41 The cost of an instrumented vehicle study will depend on the sample size. The required sample size depends on the data of interest and also will be constrained by the available budget. Read the entire page →
From page 42... ... 42 Guide to Truck Activity Data for Emissions Modeling longer than some threshold represent an engine-off condition. However, it is preferable to have ECU data so that actual cases of engine on/off can be identified and also because this is likely to provide more accurate locational and movement data than GPS alone. Read the entire page →
From page 43... ... Starts and Soak Times 43 Thus, one data file may consist of more than one trip if the engine is turned off and then on without a key-off event. On the other hand, a data file may not consist of any trip if the key is switched on and then off without an engine-on event. Read the entire page →
From page 44... ... 44 Guide to Truck Activity Data for Emissions Modeling into MOVES inputs for starts per vehicle and start operating mode (soak time) distribution. Read the entire page →
From page 45... ... Starts and Soak Times 45 Dwell times were provided by StreetLight, expressed as an indexed trip count in each dwell time bin. These bins were set up to match the MOVES start OMDs as closely as possible. Read the entire page →
From page 46... ... 46 Guide to Truck Activity Data for Emissions Modeling the number of estimated starts should be increased by about 19 percent and the fraction of start operating mode with soak time less than 6 minutes increased by about 65 percent, to account for the undercounting of starts when using only a GPS unit that records key-on events rather than engine-on events. The increased fraction in this start operating mode should then decrease the fraction of the other start operating modes proportionally. Read the entire page →
From page 47... ... Starts and Soak Times 47 aWeekend results are shown in Case Study #6 (see Appendix F, available in NCHRP Web-Only Document 261) Read the entire page →
From page 48... ... 48 Guide to Truck Activity Data for Emissions Modeling 6.4.4 Other Resources Case Study #3 (see Appendix C, available in NCHRP Web-Only Document 261) describes the estimation of starts data using StreetLight GPS data. Read the entire page →

From page 34...

... 34 6.1 Overview MOVES uses data regarding the number of starts by time of day and the distribution of soak times in the estimation of engine start emissions and evaporative fuel vapor losses (soak time is defined as the length of time the vehicle engine remained off prior to being started)