The user has three options for calculation of queue length. One option is referred to as the Australian method. It calculates the mean back of queue after start of green, and must be multiplied by a peaking factor to arrive at a design queue length. This method includes a term that calculates the number of vehicles remaining after the end of green, and experience indicates that the resulting queues over-estimate the actual mean queues.
The second method is a Design Queue Length calculation, which computes the mean maximum queue length at start of green, and then computes the mean maximum back of queue some time after the start of green, and then estimates the 95th percentile design queue by multiplying this mean by a factor of 2.
The third method is known as the back of queue methodology and it provides a greater variance in the expected queue lengths due an analysis that expands beyond the 95th percentile queue. This model for predicting queue lengths is described in Appendix G of the HCM 2000.
All three methods provide a queue length in terms of total vehicles by lane group. If the user wants stacking distance per lane, these queues need to be multiplied by an average vehicle length in feet and divided by the number of lanes in the lane group.
Users select the desired method from the Options…Global Data… Parameters dialog box. Note that there is a field provided here for the average vehicle length to be used. This is needed for the Design Queue calculation method, but the queue lengths are still reported in terms of vehicles (not distance).