Start-up lost time happens when a traffic signal changes from red (stop) to green (go).
Some amount of time elapses between the signal changing from red to green and the first queued vehicle moving through the intersection.
There is then an additional amount of time for the next vehicle to begin moving and pass through the intersection, and so on.
When no observations have been made, the start-up lost time is assumed to be 2.0 seconds as a default value.
is the portion of the yellow and all-red times during which vehicles are illegally in the intersection and has a default value of 2.0 seconds in HCM.
[2] In this study, clearance lost time was measured in the field and compared with the default values specified in HCM and ALDOT's manual.