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Transit 101: The Load Factor


Transit 101: The Load Factor

The Load Factor Defined

Load factor is generally defined as how crowded a public transit vehicle must be before additional service is added. It is usually written as a decimal point to two places which represents the percentage of the seats that are filled. For example, a 1.00 load factor means that every seat on the bus is full, 1.25 means that every seat on the bus is full and the number of standees equals 25% of the number of seats on the bus, and so on. In terms of assessing required service levels transit systems usually determine the average load factor at the peak load point.

The industry standard load factor for crowding is 1.25. In other words, in a low floor 40 foot bus that has 38 seats the bus will be described as crowded if more than 48 people are on board (38 seats + (38*0.25)) = 48. Buses on express routes, especially routes that travel on expressways, will often have a load factor of 1.0, i.e. no standees, because many consider it unsafe for buses to travel at high speed with people standing up.

Load Factor by Time of Day

The 1.25 load factor is usually used all day long. Some transit properties, however, utilize a different load factor during off-peak times. For example, the Toronto Transit Commission uses a 1.0 load factor for off-peak service. Although on its face it may seem expensive to have such a low load factor, it promotes similar all-day frequencies, which reduces the peak-base ratio and therefore saves money on overtime, spread time, and guarantee time.

Load Factor by Frequency of Service

Similarly to time of day, most transit properties have the same load factor no matter how often the particular route operates. However, this is poor customer service. Consider two situations: in one, a full bus passes you up and you must wait another ten minutes; in the other, a full bus passes you up and you must wait another hour. Obviously, the negative effect to the passenger in the second case is much worse than it is in the first case. Therefore, the transit agency should have a lower load factor for routes that operate less frequently to guard against pass-ups. A side benefit to having a lower load factor for these routes is that it kind of pushes them to operate more frequently, which provides better service to the customer on that front as well.

Load Factor by Type of Bus

The 1.25 load factor was developed during a time when all transit vehicles were high floor. The difference in the number of seats between high floor and low floor buses is dramatic. A 40 foot high floor bus can have as many as 47 seats, whereas the same size low floor bus frequently has only 38 seats, which was mentioned above. This change alone has increased the number of standees on board buses. In addition, while on high floor vehicles standees can spread throughout the length of the vehicle, on low floor buses passengers as a rule do not stand either on the stairs to the higher portion of the vehicle in the rear or in the higher portion itself.

In effect, the combination of more standees than a high floor vehicle and a vehicle which in actual operation does not hold as many standees as a high floor vehicle means that a low floor bus feels crowded at a much lower load factor than a high floor bus does. In addition, the increasing number of wheelchair passengers further reduces not only the number of available seats but also standing room. Overall, the time has come to reevaluate load factor in today's low floor world.

Observation of crowded buses in action suggests that 1.2 would be a good load factor to employ in low floor buses. This change would mean that instead of ten standees at the maximum load point being the threshold to triggering increased service it would be eight standees. Adopting this standard would reduce crowding both at the front, especially the section of the aisle in between the wheel wells, and in the back by the rear door. Crowding in these locations can cause significant delays.

The above load factor change is directed at systems which use low floor 40 foot size vehicles and also do not use prepaid fare mechanisms. Because there is no congregation at the front to pay fares, systems and vehicles that use prepaid fares, such as light rail lines, can employ a higher load factor. In addition, articulated buses, which seem to have more standing room than regular size buses, can also maintain a higher load factor.

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