It seems to me that during rush hours, more passengers alight from the front entrance of the bus rather than from the rear entrance. This could mean one of several things:
1)That passengers who board earlier take longer trips.
2) That passengers who board later drop earlier.
Taken together, there is some evidence that people use buses for one of two modes, trunk or short trips. It is correspondingly less efficient if a service caters to both types of passengers; much of the vehicle capacity is taken by trunk passengers, whereas the frequent alighting and boarding reduces the overall speed of the route.