MOVES has no start emissions for the certain source types in certain hours of the day. While we know that a non-zero number of these source types do start late at night, our activity data on these trucks and buses did not include activity in these late-night hours. In this case, we allocated all starts to the hours where data were available.
You can confirm this by looking at the SampleVehicleTrip table in the MOVES default database. This table is used to determine the number of starts and when they occur. It also calculates soak times. For some source types (e.g., 42, 43 & 52) there are no trips beginning in hours 2 through 4 and 21 through 24. If you have detailed data on start times and soak times for these vehicles during those hours, you can enter those data in the Starts tab of the County Data Manager in County Scale.