Traffic Counts

The Department of Highways and Transportation maintains a listing of 24-hour “average daily traffic” counts (ADT’s) for most of the county, maintained collector, and arterial streets. Most local streets (i.e., subdivision streets) are excluded, for they typically have low, yet fairly static daily and annual numbers.

Inquire About Trends & Road Counts
Department of Public Works does not post or publish this information primarily for the reason that the count program is ongoing at all times and is routinely updated. Interpretation of count data and terms can be confusing to a lay person. For this reason, Department of Public Works invites interested parties to contact us directly to inquire about specific roads and trends.

The Maryland State Highway Administration annually re-counts many locations on state highways and roads. They produce an annual map of these counts. Be advised that you will need Adobe Acrobat Reader to view the file.

Count Machines
One should not be immediately alarmed that a road upgrade may be pending if you see a count machine (as evidenced usually by a rubber tube across the road connected to a toaster-sized box) on your street. Often, this is merely a regularly scheduled event to update our database of information.

Intersection Turning Movement Counts
Neither the County nor the State performs regular “intersection turning movement counts.” These counts involve counting each movement, i.e., right turn, left turn, or through movement, that occurs at an intersection. Usually these counts are recorded over 2 or 3-hour windows of time, such that the “peak hour” within that window can be derived. Typically, a private consulting firm performs this style of count. This type of information is also used in determining “traffic signal warrant” thresholds and “level of service” analysis.