PHOENIX – While 2020 presented many challenges, the Arizona Department of Transportation continued to serve drivers in northern Arizona by using different methods, including the innovative bridge slide, to improve bridges to keep cross-country commerce flowing and increase the mobility of local traffic.

In Flagstaff, ADOT completed the replacement of the Fourth Street bridge over Interstate 40 on the east side of town in just six months using the innovative bridge slide method. The slide method allowed ADOT to construct the bridges to one side, then slide them into place over one long closure which greatly reduced the impact to the traveling public.

The new bridge improves safety, traffic flow and mobility in the area by increasing the number of lanes for vehicles to use and adding a protected path for bicycles and pedestrians on one side of the bridge. The protected path connects the Flagstaff Urban Trail System across the interstate.

Along Interstate 15 through the Virgin River Gorge, ADOT resurfaced the decks of Bridge No. 2 and Bridge No. 5, while Bridge No. 4 received a new deck. Work was completed this summer after important additional repairs were made. These improvements will ensure the continued life of these bridges to safely move cars and trucks cross-country.

For this project, ADOT used a first-of-its-kind queue warning system that included portable message boards informing drivers of stop-and-go traffic ahead. Using equipment that detects traffic in real-time, the system is designed to help reduce collisions as traffic builds.

ADOT also improved the Interstate 17 bridge over McConnell Drive as you come into Flagstaff. The project, which began in 2019, involved a full bridge deck replacement, bridge widening and sidewalk construction on the north side of McConnell Drive.

For more ways on how ADOT continues to serve drivers in northern Arizona, visit azdot.gov/projects and click on the North Central District.

PHOENIX – Several major bridge and intersection replacement projects in southern Arizona presented a big challenge for the Arizona Department of Transportation in 2020: How to replace existing structures or entire interchanges without closing highways on projects that last up to two years.

The agency applied several innovative approaches to do just that, keeping passenger vehicles and commerce moving while minimizing potentially disruptive restrictions and closures.

Drivers are benefiting from the strategies at several key projects: The Interstate 10/Houghton Road interchange in Tucson, the Pinto Creek Bridge replacement on US 60 near Globe, a bridge replacement project on SR 77 in Winkelman, and the I-10/Ruthrauff Road interchange replacement project in Tucson.

The I-10/Houghton Road interchange project in Tucson began in August, a project that involves replacing a two-lane Houghton Road bridge with a six-lane diverging diamond interchange, along with rebuilding all ramps. While replacing an interchange sometimes requires extensive closures, ADOT will complete this project with only a three-month closure of two ramps - both of which have already reopened. The other two ramps and bridge are being constructed next to the existing lanes of traffic, and traffic will eventually shift to the new pavement. For the remainder of the project, only overnight closures are anticipated as traffic flows through the busy work zone.

On US 60 between Globe and Superior, ADOT has been working since late 2019 to replace the 70-year old Pinto Creek bridge in an area with rugged terrain and hour-long detours around any highway closures. However, the project required months of blasting that could only occur when US 60 was closed. ADOT’s solution was to limit closures to four hours at the same time and on the same three days of the week, ensuring motorists had a predictable schedule to plan their travels. Since the blasting wrapped up earlier this year, the highway has remained open while the project team works on the new bridge next to the existing structure. A five-day closure is anticipated toward the end of the project in 2021 as crews realign the road to the new bridge.

In Winkelman, ADOT is working to replace the two-lane SR 77 bridge over the Gila River without closing it or shifting the highway. Crews are able to do this by essentially cutting the bridge in half and rebuilding one side of the structure at a time. Since the project began in late 2019, traffic has continued to use the bridge, restricted to one direction at a time as a temporary signal regulates which direction can proceed. Delays are generally less than 15 minutes, with occasionally longer delays for two weeks at a time when new bridge girders have been set into place. The new bridge will open by summer 2021 without any extended closures of SR 77. 

At I-10 and Ruthrauff Road, one of the most heavily traveled segments of the Interstate in Tucson, ADOT has been working since January to replace a 60-year-old interchange without closing the highway. ADOT has maintained three lanes of travel in each direction during peak hours with several traffic shifts onto either the frontage road or newly rebuilt lanes of I-10. While the interchange has been closed most of 2020 and the project won’t be complete until late 2021, ADOT has made it a priority to reopen Ruthrauff/El Camino del Cerro across I-10 by summer 2021 to minimize the impact of the project even as other elements of the project will remain under construction. Also, ADOT’s contract with Sundt Construction encourages an aggressive construction schedule with an early completion incentive for finishing the project 40 days sooner than the contractor’s specified completion date. The goal is to only have the interchange closed for the 2020 holiday travel season and open again before the holidays in 2021. 

PHOENIX – The conditions of pavement and bridges on Arizona’s interstate freeways rank among the nation’s best in an annual report by a nonprofit transportation research group. 

Washington, D.C.-based TRIP says that while interstate freeways across the country face increasing congestion and need significant investments for expansion and repair, just 2% of Arizona’s interstate pavement was in poor condition and 1% of bridges were in poor condition. Arizona ranked well within the upper half of states in terms of interstate pavement listed in poor condition, while only five states had lower percentages of interstate bridges listed in poor condition. 

The Arizona Department of Transportation’s latest figures show 1.1% of pavement on the state’s interstate freeways was considered in poor condition. Meanwhile, 0.9% of bridges ADOT maintains on all state highways were rated in poor condition. A poor rating does not mean a bridge is unsafe; it means repair needs have been identified in the bridge’s deck, superstructure or substructure.

“We have worked diligently to maximize the funding Arizonans allocate for transportation to deliver the safest and most reliable highway system possible,” said Dallas Hammit, ADOT’s state engineer and deputy director for transportation. 

Despite Arizona’s strong standing in the TRIP report, challenges loom.

As people drive less and stay home more amid the current public health situation, ADOT is evaluating the short- and long-term revenue implications to the Highway User Revenue Fund, a major source of funding for projects and improvements. ADOT is committed to providing a fiscally constrained construction program with prudent financial management in the months and years ahead. 

With ADOT responsible for 28,000 lane miles and 6,800 center-line miles of highway, available funding in recent years has meant that a smaller share of pavement on all state highways is considered in good versus fair condition.

Over a nine-year period, the share of pavement considered in good condition has fallen from 72% to 48% on interstate freeways, from 68% to 32% on non-interstate national highway system highways and from 44% to 19% on state highways that aren’t part of the national highway system. This drop in pavement condition is expected to worsen with time, if funding levels remain the same, as the deterioration is occurring at exponential rates.

Among the state highway system's 4,800 bridges, the share rated in good condition has fallen from 78% to 59% in recent years.

Arizona’s relatively dry and mild climate helps pavement and bridges last longer before major repairs are needed. Bridge and pavement conditions also are inspected on a regular basis. Overall, Arizona’s highway system is relatively young, including the freeways and bridges carrying higher volumes of traffic on Phoenix-area freeways. As the pavements and bridges age, the cost and effort of maintaining them increases.