A volume count analysis may use the following types of counts:

Discussions of each of these types of counts follow.

Volume counts should be shown on the Traffic Survey Count Analysis Sheet (discussed in Section 7 of this chapter) for review in the office following the field work.

A vehicle count at an existing location should include the number of vehicles entering the location on each approach. Counts are recorded as vehicles cross the stop bar and enter the intersection. Tallies should be recorded for each quarter hour for the duration of the count. Ideally, counts are conducted on a “representative day” (defined later). The duration of the count should be 16 consecutive hours. This time span should contain the greatest percentage of traffic during the 24-hour time period. Traffic patterns, such as when the highest vehicle and pedestrian volumes occur, should help determine the beginning and ending times for the count. These patterns may vary from one location to the next.

Representative Day.

A representative day is normally an average, mid-week day, such as Tuesday, Wednesday, or Thursday. Monday or Friday may be acceptable if traffic volumes are representative of a mid-week day. Local knowledge of commercial habits, such as early closings or evening shopping, is essential in choosing a truly representative day. Under unusual conditions when recreational traffic is significant, traffic counts taken on weekends may be compared against the accepted warrants.

With passenger or commercial vehicles, manual turning movement counts are always preferable, as they provide both the basic data for justification as well as detailed guidance for design.

Manual traffic counts may be recorded on the Vehicle Volume Summary Sheet (See Appendix A of this manual).

For locations under construction or not yet in existence, the Transportation Planning and Programming Division (TPP) estimates the anticipated average daily traffic (ADT) volumes at the district’s request. To aid TPP in making such an estimate, 24-hour machine counts should be made along each approach open to traffic. An up-to-date map of the area and a layout of the location as it will be constructed should also be provided. (If construction will be staged and the location opened to traffic in increments, layouts at various stages of construction are recommended.) If a major traffic generator (shopping center, industrial plant, recreational facility, school, etc.) is in operation (or expected) within a 0.5 mile radius of the location, the information should be included in the request to TPP.

Using the projected ADT volumes, the following general guidelines can be used to obtain an estimate of vehicle count data:

The maximum 8-hour volume

is generally between 50 percent and 60 percent of the ADT, with the average being approximately 52 percent. In an urban area with a high ADT, the percentage is generally between 55 and 60 percent.

The average hourly volume

of the maximum 8‑hour volume is generally between 6 percent and 8 percent of the ADT (maximum 8‑hour volume divided by eight.)

The lowest hourly volume

(eighth highest hour) of the maximum 8‑hour volume is generally between 5 percent and 6 percent of the ADT with an average value of approximately 5.5 percent. It is also approximately 80 percent of the average hourly volume or 10 percent of the maximum 8‑hour volume. This value is the basis for comparing the anticipated volumes with the volume warrants for signalization found in the

Texas Manual on Uniform Traffic Control Devices

(TMUTCD).

The lowest hourly volume

(eighth highest hour) for a “grid system” of existing signals within a city is assumed to be 5 percent of the ADT.

The peak hour volume

(highest hour) is generally between 6 percent and 10 percent of the ADT. The lower values are generally found on roadways with low volumes. The average value is approximately 8.4 percent of the ADT.

Pedestrian volume counts for each cross walk should be made during the same period as the vehicle volume count. Tallies should be recorded for each quarter hour for the duration of the count.

Pedestrian counts are not required in sparsely settled rural areas or at other locations where it is apparent that pedestrian movement is negligible. The signal installation must comply with the latest version of the Americans with Disabilities Act and the Texas accessibility standards.

Forms.

The Pedestrian Volume Summary Sheet can be used to record pedestrian counts in the field (See Appendix A).

School pedestrian counts should be made on a normal school day during the hours of greatest crossing activity. Obtaining the necessary count information for a school crossing study involves:

Other factors to be considered at the crossing are:

Forms.

The necessary forms with instructions for conducting a school pedestrian count are:

For procedures for Determination of Need for Traffic Control at School Crossings, see Appendix B of this manual.