For roadway segments, 24-hour counts can be used to determine the time of day (e.g., AM, midday, or PM) peak hour or peak period. For intersections, segment counts or TMCs can be used to determine the peak hour or peak period. The peak hour is the hour in which the sum of vehicle volume during four consecutive 15-minute count intervals is the highest.

Figure 3-2

shows an

example

of 24-hour traffic counts for a corridor, which can be used for AM and PM peak hour selection. This figure shows that the AM peak hour probably occurs sometime between 7:00am and 9:00am and that the PM peak hour probably occurs sometime between 3:30pm and 5:30pm.

Typically, the morning and evening peaks are used for analysis. Unique circumstances could necessitate the analysis of a midday peak, weekend peak, or other atypical peak. This is an important consideration near malls, commercial corridors, stadiums, schools, and unique land uses because these locations may cause sporadic or irregular traffic patterns. In oversaturated conditions, peak spreading may occur and necessitate a peak period selection rather than a peak hour. It is suggested that selection of peak hour/period be documented.