Originally Published: October 29, 2017 6:02 a.m.
Looking for the quickest route between Prescott and Prescott Valley? Many local drivers will tell you that Pioneer Parkway/Highway 89A/Glassford Hill is your best choice.
At least compared with Highway 69 and its myriad traffic signals, the freeway-like interchanges and lighter traffic on Highway 89A have long allowed for largely uninterrupted passage.
Imagine, though, if 89A’s traffic numbers exceeded those on Highway 69, and drivers faced long lines at interchanges to merge onto the highway.
Local experts say such a scenario is not so far off — especially with the numerous housing/commercial developments that are in the works along the Highway 89A corridor.
“With growth, we’re going to see 89A surpass 69,” Alvin Stump, district engineer for the Arizona Department of Transportation (ADOT), said this past week. “(The Highway 89A area) is where the growth is.”
The traffic numbers already are telling.
Central Yavapai Metropolitan Planning Organization (CYMPO) Administrator Chris Bridges points out that traffic growth on Highway 89A has hovered in the 7-percent range for the past several years.
That is well above the growth that is typical on area roads. “For Yavapai County, a lot of corridors see about a 3-percent average,” Stump said, noting that the average annual growth on 89A stands at 4.8 percent.
More than 30,000 vehicles per day currently use 89A at its busiest point between the Larry Caldwell Drive interchange and the Glassford Hill Road interchange, and with the current growth rate, the number will soon reach the 40,000 mark, say the experts.
While still less than the 45,000 to 50,000 vehicles that crowd Highway 69 each day at its busiest points, the rapid rise on Highway 89A was enough of a concern to trigger a multi-agency traffic study on the highway.
This past June, ADOT hired the AECOM engineering firm to do a traffic study on the eight miles or so of Highway 89A between Highway 89 and Robert Road. CYPMO is paying $120,000 toward the cost, while Yavapai County is putting in $100,000, and ADOT is contributing $50,000.
The study is expected to be complete by about March, Stump said. Meanwhile, a public meeting is scheduled for 6 p.m. Dec. 12, at the Prescott Valley Public Library, 7401 E. Civic Center Circle, to allow local residents to weigh in.
Stump says the study will look into the expected traffic impacts, as well as possible mitigations.
Among the possible solutions will be the addition of a highway lane, he said. “The rule of thumb is when you start getting over 40,000 (vehicles a day), you start to think about adding a third lane,” Stump said.
Another possibility: Acceleration of planning for Great Western Drive — a route that Stump says would head north near the water tanks along Highway 89A, would skirt the Prescott Airport, and would ultimately connect up with Highway 89 to the north. Such a route would take pressure off both Highway 89 and Highway 89A.
While the Great Western idea has been around for years, 2014’s update of the Regional Transportation Plan for the CYMPO area pushed off the new road — along with several other improvements — because population growth during the Great Recession had fallen far behind earlier projections.
Now, Stump said, growth is back, and the new route could help to handle it.
“We have a lot of growth challenges, and we’re trying to figure out what our needs are,” he said. “We might have to look at the Great Western a lot sooner than people think.”
Central to the transportation study will be the projected growth along the Highway 89A — a corridor that has seen a number of new developments being built and proposed.
In recent months, for instance, the City of Prescott has reviewed plans for the Deep Well Ranch project, which is projected to bring as many as 10,500 new homes to 1,800 acres near the corner of Pioneer Parkway and Highway 89.
In addition, Arizona Eco Development recently introduced plans to the Prescott City Council to seek annexation into city limits of more than 3,000 acres north and south of the Granite Dells Parkway interchange. That project could involve nearly 4,000 homes. (City officials have yet to receive the official application for the Arizona Eco annexation.)
And already in the building phase is the Granite Dells Estates project, which is bringing hundreds of new homes to the area south of Highway 89A.
In addition, a number of Highway 89A-area projects are in various stages of planning/development in Prescott Valley.
“All of the developments are popping up seemingly at the same time,” Bridges said, noting that the planning has prompted the questions: “What are the traffic volumes? And what will the impact be?”
Depending on the type of housing unit and its location, Stump says estimates have each home generating four to six vehicle trips a day. The study will take the growth numbers into consideration and will attempt to gauge origin and destination to estimate traffic impacts.
Because Highway 89A was built with access-controlled interchanges, Bridges predicts that drivers will continue to gravitate to it as a relatively quick, hassle-free route.
But, he and other local experts caution that the interchanges will soon be causing traffic issues. “People getting off and on is what will be causing the problem,” Bridges said.
Prescott Planning Manager George Worley agreed, noting that several of the 89A interchanges could be problematic in the future.
The Granite Dells Parkway, which the city built several years ago in anticipation of growth, “Is not a problem,” Worley said, adding, “That should work for the foreseeable future.” But, he said, “Larry Caldwell is a different story,” as is the Highway 89/89A interchange.
To give perspective to the expected traffic volumes, Stump pointed out that Intestate 17 attracts about 50,000 to 60,000 vehicles a day on the weekends.
While stressing that the interstate’s steep grade aggravates traffic there, Stump said those type of numbers come with traffic problems.
“When you start getting into the 45,000 to 50,000 range, you’re going to start having gridlock,” he said. “Also, the interchanges start failing.”