Passenger lift traffic calculations A calculated interval of 22.1 seconds is considered to be a good lift system by both British standards BS5655 : Part 6: 1990 and CIBSE guide D:2000. Therefore, to increase the car speed by 50% from 1.0 m/s to 1.5 m/s would theoretically improve the round trip time by approximately three seconds and therefore the interval time by 1.5 seconds as the lift(s) will only achieve full speed during the express return to the main floor. However this "improvement" of 1.5 seconds does not take into account the additional time element for the increased acceleration and deceleration times at a faster car speed. The handling capacity is defined as the number of persons that can be transported from the main terminal floor to the upper floors of a building during a 5 minutes/300 seconds period of up-peak activity during which time the demand is the heaviest. This is determined by finding the number of lift car trips and multiplying by the average number of passengers (80% load capacity of the lift cars) carried in those five minutes. The value for % handling capacity is determined by dividing the number of passengers transported within the up-peak period by the effective building population.