Word on the street: PAG traffic data collection keeps planners, engineers, private sector in the know

Tucson metro area streets have a lot of traffic. Not exactly news to anyone, but just how much traffic is on our regional streets and how do we know?

That’s where Pima Association of Government’s transportation planning and travel forecasting comes in.

“The traffic and travel data PAG captures not only provides fascinating insights into the travel behaviors in the region but supplies regional leaders with invaluable information to make informed long-term planning decisions,” said PAG Executive Director Farhad Moghimi.

PAG staff work with a contractor and other jurisdictions to gather traffic data across the Tucson metro area. In all, data are gathered at hundreds of intersections and select roadways producing enormous amounts of information that government agencies and private companies rely upon.

“Knowing what’s happening on the roads is fundamental to so many aspects of planning,” said PAG Modeling Coordinator James Tokishi.

Tokishi manages the traffic data program for PAG, sorting through and analyzing the volumes of information captured. That information helps inform the work across many program areas at PAG and other agencies.

A major function area at PAG where traffic data plays an important role is in the development and updating of long-range planning reports. As the federally mandated metropolitan planning organization for Pima County, PAG is responsible for long-term transportation planning.

“Part of the Regional Mobility and Accessibility Plan (RMAP) requires we look at traffic counts to identify areas of congestion and delay,” said PAG Transportation Planning Director Jeanette DeRenne.

Counting cars

Want to know which intersections have the most traffic during peak travel hours?

Click here to find out

To achieve this mandate, PAG coordinates with member jurisdictions and the community every four years to develop the RMAP. The plan identifies the region’s long-range transportation needs and anticipated revenues during the plan period. The plan also requires meeting air quality standards, which traffic data can aid in making projections.

Along with other elements, the RMAP update contains data and maps to show what existing congestion situations on regional streets look like, estimates of what roadway conditions would look like in 30 years if projects identified in the plan are built, and an estimate of what conditions would be in 30 years if those same projects are not built. These projections are developed, in part, using traffic count data as a baseline.

“It’s also helpful with project selection,” DeRenne said of the traffic data program, noting jurisdictions can analyze the data to determine traffic patterns and inform planning for new or enhanced roadway projects.

How it’s done

The data can be collected by various means, including extending rubber tubes on roadways, radar monitoring, or video recording, all of which have advantages and disadvantages.

Those old school rubber tubes across the road connected to counting devices are still the most common method used to count vehicles, best used for short-term vehicle counts or for vehicle classification on single-lane roads.

Radar collection is another method useful to count cars, especially at locations where rubber tubes cannot be used, such as along the Sun Link route.

Video is an increasingly common method to count vehicles. Permanent cameras mounted at intersections or temporary cameras at select locations gather traffic information as vehicles cruise past. These systems can use automated counting or require human review of recordings.

In all, PAG collects traffic data from about 500 roadway segments and 300 intersections every year, following federal guidelines for three- and six-year count cycles.

“The traffic count program not only helps with planning for long-range actions but also provides a source of real-time information that can be used to identify any trends and/or patterns that may warrant interim or short-term modifications and improvements,” said PAG Director of Transportation Services Rick Ellis.

What the data show

Traffic counts reveal many interesting trends and behaviors of the traveling public in our region.

Tokishi said one useful trend which recent data collections have shown is how the COVID pandemic has changed driving behaviors across the region.

“Post pandemic trend patterns are noticeably different from the pre-pandemic era,” he said.

For instance, traffic volumes in general have not fully returned to pre-pandemic levels even though closures and reduced hours of operation have long since ended. While the traffic data alone can’t explain this trend, it’s possible to see a correlation and extrapolate how the continuation of remote work and school, and hybrid schedules, are part of what’s at play.

The rise of online shopping and delivery services during the pandemic also changed behaviors. The increase in delivery of prepared food, grocery items and general consumer goods is likely to continue, according to the U.S. Department of Commerce, which predicts the trend to remain at least through 2025 as “consumers have been acclimatized towards the convenience of online shopping.”

Traffic data also play an important role in private sector decision making.

Commercial, retail, residential and other developers depend on traffic data to determine the viability of proposed projects. Additionally, DeRenne explained, many largescale development projects require traffic impact studies, which the data PAG collects can help inform.

Others who use traffic count information include:

  • Transportation engineers and planners throughout the region use traffic data to identify existing traffic problems and solutions.
  • The Arizona State Legislature and U.S. Congress rely upon the data to make decisions on the need for and allocation of state and federal funds.
  • Regional, state and federal air quality experts analyze the data to monitor traffic-related pollutants and conformance with air quality standards.

Of course, the public also can comb through the data. A searchable map on the PAG traffic count site allows even casual users to locate traffic counts on specific stretches of roadway or intersection, view year-over-year data, or develop custom data searches.

Find the map page here, or access it through this page, which includes additional information and instructions on how to use the traffic data map.