Updated February 7, 2022

ADOT will update this page regularly to reflect common questions and themes. Please check back periodically if you have a question or concern, as it may be addressed here.

I-10 Broadway Curve Improvement Project General Information

  • What is the Broadway Curve?

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    The Broadway Curve is the section of Interstate 10 between Baseline Road and 40th Street. I-10 “curves” beneath Broadway Road. Much of the construction will occur in the Broadway Curve area.

  • What are the boundaries of the project?

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    The project is on 11 miles of Interstate 10 between the Loop 202 (Santan/South Mountain Freeway) and Interstate 17 near Phoenix Sky Harbor International Airport. Additional work will occur on approximately 1 mile of east- and westbound US 60 (Superstition Freeway) between I-10 and Hardy Drive and on approximately one mile of north- and southbound State Route 143 between I-10 and the southern end of the SR 143 bridge over the Salt River.

  • What are the major components of the project?

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    This is ADOT’s largest urban freeway reconstruction project. The major components include:

    • Widening Interstate 10 to six general purpose lanes and two high-occupancy vehicle (HOV) lanes in each direction between US 60 (Superstition Freeway) and Interstate 17, and adding a fourth general purpose lane in each direction between Ray Road and US 60
    •  Adding Collector-Distributor roads parallel to I-10 between Baseline Road and 40th Street to separate through-traffic on I-10 from local traffic entering or exiting the highway
    • Rebuilding the I-10 interchange with State Route 143 to improve traffic flow and create direct connections to and from SR 143 for drivers in the I-10 high-occupancy vehicle (HOV) lanes
    • Replacing the Broadway Road bridge over I-10
    • Replacing the 48th Street bridges over I-10
    • Widening the I-10 bridges over the Salt River
    • Building two bridges for pedestrians and bicyclists over I-10 between Baseline and Broadway roads (at Alameda Drive and the Western Canal) and improving the Sun Circle Trail crossing at Guadalupe Road
    • Building sound and retaining walls where warranted
  • Where will most of the work occur?

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    Much of the construction will occur in the Broadway Curve, between Baseline Road and 40th Street, including reconstruction of bridges and interchanges and the addition of the Collector-Distributor roads. This work also will impact sections of State Route 143 and US 60 (Superstition Freeway). Additional highway-widening and improvement work also will occur on Interstate 10 throughout the 11-mile project area.

  • Why is ADOT doing this work here and now?

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    As the designated Metropolitan Planning Organization for the Maricopa County region, the Maricopa Association of Governments (MAG) plans and funds the Regional Transportation System in Maricopa County and sections of Pinal County. This project is identified in the MAG Regional Transportation Plan (RTP), which is funded by the half-cent sales tax Maricopa County voters approved in 2004 through Proposition 400. MAG identified the need for this project to reduce travel times on Interstate 10 during peak hours; improve airport access; support ridesharing and transit; and prepare the region for future growth projections. MAG programmed funding for delivery of this project in 2021-2024. Now, ADOT and the Developer are responsible for design and construction. ADOT will operate and maintain the freeway when work is complete.

  • Will the Warner Road overpass be widened as part of this project?

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    The Warner Road overpass will not be widened as part of the I-10 Broadway Curve Improvement Project. The need for capacity improvements at the Warner Road interchange was identified in the 2017 I-10/I-17 “Spine” Corridor Master Plan conducted by the Maricopa Association of Governments. However, funding for these improvements was not included in the scope of the I-10 Broadway Curve Improvement Project. The project scope does include widening the westbound I-10 off-ramp at Warner Road to accommodate a second right-turn lane onto eastbound Warner Road to reduce traffic backups. Although widening the Warner Road overpass is not included in the scope of this project, it could be included in a future project if funding is available.

  • Does the project design take into account traffic growth and “induced demand”?

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    Yes. The Maricopa Association of Governments (MAG) completed Travel Demand Modeling (TDM) for the Maricopa County region through design year 2040. The Arizona Department of Transportation then applied volume projections from the TDM to the I-10 Broadway Curve Improvement Project’s schematic design; in addition, ADOT used microsimulation modeling to verify that the lane configurations and other project elements meet the needs of the TDM, and they do. The TDM also takes into account “induced demand” – the thought that increasing roadway capacity encourages more people to drive – through 2040. The microsimulation model confirmed that the project is accommodating induced demand as well. Finally, ADOT also used data gathered during development of MAG’s Spine Corridor Master Plan, which analyzed long-term strategies to improve mobility in a 31-mile corridor beginning in north Phoenix at the I-17/Loop 101 (Pima Freeway) interchange, through the I-10/I-17 interchange near downtown Phoenix, and further south to the I-10 interchange with Loop 202 (Santan/South Mountain Freeway). Data from the “Spine Study” also influenced the development and design of this project.

Project Benefits

  • How does this project benefit me?

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    This project benefits the entire metropolitan-Phoenix area as it creates a safer, more-efficient freeway system for drivers throughout the region. According to an economic evaluation conducted in 2020 by the Maricopa Association of Governments (MAG) the improvements will save motorists 2.5 million hours annually otherwise spent in traffic – totaling $130 million a year in time savings. Other key benefits include:

    • Reduced travel time during peak hours
    • Improved access to and from Phoenix Sky Harbor International Airport
    • Improved access to the 4,600+ businesses located along the corridor, including 50 of the region’s largest employers, as well as colleges and retail centers
    • Improved safety by reducing lane changes and “weaving” on Interstate 10 in the Broadway Curve and on State Route 143 at University Drive
    • Support for ridesharing and transit
    • With the addition of new overhead message signs, improved travel-time reliability and communication between ADOT and motorists about changing traffic conditions
    • Better prepare the the MAG region for future growth projections, which indicate a 25% increase in traffic by 2040
  • How will project improvements reduce lane changes made by drivers merging from westbound US 60 (Superstition Freeway) to westbound Interstate 10?

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    The addition of the Collector-Distributor roads will help eliminate many of the lane changes that currently occur in this busy area where the two freeways converge.

  • What are the benefits of reducing lane changes in the Broadway Curve?

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    Reducing the need to make lane changes, and “weaving” in and out of travel lanes, helps improve safety and traffic flow and reduce congestion.

  • Will this project generate more jobs?

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    The project is forecast to generate 1,400 new construction jobs and 250 new long-term jobs in the region, according to an economic evaluation conducted by the Maricopa Association of Governments in 2020.

  • Will the project include a wrong-way driver detection system?

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    The Interstate 10 Broadway Curve Improvement Project will expand ADOT’s wrong-way driver detection capabilities along about 10 miles of I-10 between Chandler Boulevard and 32nd Street.


    When the project is completed in late 2024, it will include a real-time system featuring thermal cameras to detect wrong-way vehicles (and bicycles) on a ramp; internally illuminated Wrong-Way signage on ramps facing potential wrong-way drivers; and accessories required to provide a complete, fully functioning wrong-way detection system along I-10 in the project area that is integrated with the ADOT’s software and equipment. It will function like the existing wrong-way detection system so motorists and law enforcement officers are quickly and proactively alerted when a driver enters the highway or travels in the wrong direction of the highway.


    Wrong-way detection system features will be installed in conjunction with the I-10 Broadway Curve Improvement Project in the following locations:


    1.      32nd Street/University Drive eastbound and westbound off-ramps at I-10.

    2.      40th Street eastbound and westbound off-ramps at I-10.

    3.      University Drive northbound and southbound off-ramps at SR 143.

    4.      Broadway Road eastbound and westbound off-ramps at I-10.

    5.      Priest Drive westbound off-ramp at US-60 (Superstition Freeway).

    6.      Baseline Road eastbound and westbound off-ramps at I-10.

    7.      Elliot Road eastbound and westbound off-ramps at I-10.

    8.      Warner Road eastbound and westbound off-ramps at I-10.

    9.      Ray Road eastbound and westbound off-ramps at I-10.

    10.  Chandler Boulevard eastbound off- ramp at I-10.

  • How will this project improve getting to and from Phoenix Sky Harbor International Airport?

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    Much of the major reconstruction efforts associated with this project will be centered on the traffic interchange at Interstate 10 and State Route 143. The project will add a direct-connect high-occupancy vehicle (HOV) ramp from westbound Interstate 10 to northbound SR 143 and from southbound SR 143 to eastbound I-10, providing direct access to and from the airport for carpool drivers (and other drivers who use the HOV lanes when permitted during non-peak hours). The addition of Collector-Distributor (CD) roads also will improve access for airport-bound drivers on westbound I-10 from south of Baseline Road, and from westbound US 60 (Superstition Freeway). When work is completed, drivers on westbound I-10 will exit I-10 near Baseline Road and use the CD roads to access northbound SR 143 and reach the airport.

About the Collector-Distributor Roads

  • What are Collector-Distributor (CD) roads?

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    As the name suggests, these roads will collect traffic from the Interstate 10 mainline, State Route 143 and US 60 (Superstition Freeway) and distribute it to crossroads or other highways. CD roads are similar to frontage roads, but without driveways or cross-street intersections. Once open, they will separate through-traffic on I-10 from local traffic entering and exiting the highway. The CD roads are being constructed along westbound I-10 from Baseline Road to 40th Street (generally three lanes) and along eastbound I-10 from 48th Street to Baseline Road
    (generally two lanes).

  • How will drivers know if they should remain on Interstate 10 or use the Collector-Distributor (CD) roads?

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    Signage will guide drivers to the correct lanes based on their destinations. Before the CD roads open, ADOT will provide educational information so drivers understand how to drive on them.

  • Will the Collector-Distributor (CD) roads have traffic signals?

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    No. Although traffic signals will control traffic entering and exiting the CD roads from the crossroads between Baseline Road and 40th Street, drivers will not encounter traffic signals once they are on the CD roads.

  • What is the speed limit on the Collector-Distributor roads?

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    The speed limit will be 55 mph.

Construction, Timeline and Costs

  • Why is ADOT removing the rubberized asphalt from Interstate 10 and the US 60 (Superstition Freeway) before construction begins?

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    Removing the top layer of rubberized asphalt is important so construction crews can establish their work zones and shift the travel lanes as required throughout construction. For a project of this size and scope, dozens of work zone and travel lane shifts will be necessary. Applying and removing temporary lane striping each time would create significant wear and tear on the  pavement surfaces. Also, when the rubberized asphalt is removed, workers will inspect the concrete pavement and repair areas that are cracking or beginning to break before final road-surface treatments are put down.

  • What is the construction timeline?

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    Preconstruction activity, such as relocating utilities, soil sampling and preparing right of way, began in spring 2021. ADOT anticipates construction will begin in summer or fall of 2021 and be completed by early 2025, barring unexpected delays. As always, schedules are subject to change because of unanticipated circumstances. Specific locations within the project area will be impacted only when work is occurring in or near those areas.

  • What is the project cost?

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    The contract amount with the Developer is $615,600,950. The amount authorized for construction is $729,709,314 million. The total amount including intelligent transportation system signal upgrades, right-of-way acquisition and paid advertising is $832,819,314.

  • How is the project being funded?

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    This project is funded in part by a dedicated, half-cent sales tax approved by Maricopa County voters in 2004 for projects, such as this one, identified in the Maricopa Association of Government’s Regional Transportation Plan. The Federal Highway Administration provided additional funding.

  • How is the project being delivered?

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    This project is being delivered as a Public-Private Partnership and Design-Build (DB). Unlike traditional design-bid-build projects, DB projects are delivered by teams that have one contract with ADOT for design and construction services. For this project, the DB team is known as the Developer.

  • Who is the project Developer?

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    The Developer is a joint venture between Pulice Construction Inc., FNF Construction Inc. and FlatIron Constructors Inc. known as Broadway Curve Constructors. The project designers are T.Y. Lin International Group, Stanley Consultants and Aztec Engineering.

  • What makes this project a Public Private Partnership (P3)?

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    The Arizona Department of Transportation (ADOT) procured the I-10 Broadway Curve Improvement Project as a single Design-Build (DB) contract using a Public Private Partnership (P3) approach. The DB delivery mechanism is financed by the public sector and does not include private financing.

    For this project, ADOT is the public-sector/public agency project owner. The private-sector entity is a joint venture of Pulice Construction Inc., FNF Construction Inc. and FlatIron Constructors Inc., known as Broadway Curve Constructors (BCC).

    While there is no single definition of a P3, the National Council for Public Private Partnerships (NCPPP) defines a P3 as “a contractual agreement between a public agency (federal, state or local) and a private-sector entity. Through this agreement, the skills and assets of each entity (public and private) are shared in delivering a service or facility for the use of the general public. In addition to the sharing of resources, each party shares in the risks and rewards potential in the delivery of the service and/or facility.”

    Some of the main differences between P3 projects and conventional projects can be explained by the project phasing, type of contract and risk allocation. For example:

    • Instead of procuring each phase of the project separately, the I-10 Broadway Curve Improvement Project integrated two phases – design and construction – in a single contract with the private-sector partner.
    • Also, instead of ADOT specifying exact outputs required through detailed specifications, the P3 contract has outcome-based specifications. This means the public-sector owner specifies its requirements and the private-sector partner determines the best way to meet them.
    • Finally, instead of ADOT assuming all of the risk, the risk is distributed optimally between ADOT and the private-sector partner, typically to the party best able to manage the risk. As a result, a P3 project like this can offer such benefits as potential cost savings, accelerated delivery, greater innovation and other efficiencies.


    ADOT has authority to enter into P3 agreements under Chapter 22 of Arizona Revised Statutes (A.R.S.) Title 28 or A.R.S. §§ 28-7701 et seq. You can learn more about P3s and their benefits here.

  • Why does this project include two high-occupancy vehicle (HOV) lanes between US 60 (Superstition Freeway) and Interstate 17?

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    I-10 in the Broadway Curve is one of the busiest freeways in Arizona with more than 300,000 vehicles per weekday in 2021 (prior to COVID-19) and about 375,000 vehicles a day expected by 2040. ADOT anticipates a similar increase in the number of drivers eligible to use the HOV lanes during the morning and evening rush hours. Also, because one-third of express bus passenger trips in the region use the Broadway Curve, dual HOV lanes will support use of transit.

  • What improvements are being made to the Interstate 10 Salt River bridges?

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    The bridges over the Salt River on east- and westbound I-10 (near Phoenix Sky Harbor International Airport) will be widened, including shoulders and new outside barriers. The eastbound I-10 bridge will be widened from five lanes to seven lanes with two high-occupancy vehicle (HOV) lanes. The westbound I-10 bridge will be widened from six lanes to seven lanes with two HOV lanes.

  • What changes does the reconstruction of the State Route 143 interchange mean for Broadway Road?

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    The alignment of Broadway Road will shift slightly north to provide crews enough space to build a new interchange with a new bridge, while keeping the current bridge open to traffic while that work is underway.

  • How many properties did ADOT acquire for this project?

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    A total of 33 parcels, adding up to 17.4 acres of land, were affected. This includes 13 partial property acquisitions, four full property acquisitions and several temporary or permanent easements needed to create space for the additional lanes on Interstate 10.

  • Will any changes be made to surface streets and bridges adjacent to the project?

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    This project focuses on improvements to Interstate 10 and other parts of the state highway system, including US 60 (Superstition Freeway) and State Route 143. Some local streets also will be improved in conjunction with the project. Examples include:

    • The crossroads at 40th Street and Broadway Road will receive new asphalt pavement
    • At 40th Street, crews will remove the loop ramp to access eastbound I-10 and replace it with dual left-turn lanes that provide access to eastbound I-10 from southbound 40th Street
    • The westbound I-10 off-ramp at Warner Road will be widened to accommodate a second right-turn lane onto eastbound Warner Road
    • In Tempe, 48th Street east of SR 143 will be realigned to accommodate the additional lanes being constructed at the new SR 143 and I-10 interchange
    • On Guadalupe Road, between Calle Sahuaro and Pointe Parkway East, crews will improve the Sun Circle Trail and install new LED lighting
    • On Southern Avenue, crews will make improvements in compliance with the Americans with Disabilities Act (ADA) and resurface and restripe the road between Clementine Drive and Diablo Way
    • A cul-de-sac will be installed on Diablo Way north of Southern Avenue; ADA improvements also will be made, and that 400-foot stretch of Diablo Way will be resurfaced
    • Diablo Way between Fairmont and Alameda drives will be realigned to accommodate the addition of the eastbound Collector-Distributor road.

Impacts to the highway system and local roads during construction

  • During full freeway closures, why should I follow the designated detour route when it seems faster to use the local streets?

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    Our data show drivers save time when they use the designated freeway detours instead of local streets. For example, data collected during a recent closure at peak travel times show that it took drivers using surface streets up to 5.54 minutes longer to rejoin I-10 than those who used the detour route. In this case, the detour route was 20 miles, while the surface street routes were shorter – about 12 to 14 miles.  Plus, local streets aren’t designed or built to handle interstate traffic. Save time, and our local streets, by staying on the highway detour routes.

  • Will Interstate 10 and other highways be closed during construction?

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    Yes, there will be many times when full- and partial closures of Interstate 10, US 60 (Superstition Freeway) and State Route 143 will be necessary. Highways other than I-10 also may be affected because they will serve as detour routes; and some highway ramps and local crossroads also will be impacted at times. ADOT will announce planned closures in advance and provide detour route information so motorists can plan their routes and travel times. ADOT recommends everyone who lives, works or drives in the project area identify the detours and allow for extra drive time while construction is underway.

  • Will I be able to get to Phoenix Sky Harbor International Airport during construction?

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    Yes, but you might need to take a detour and should allow extra drive time. ADOT understands the importance of maintaining access to and from Phoenix Sky Harbor International Airport and is working with airport officials to provide information about traffic restrictions and detours. ADOT will continue to work closely with airport officials to share information and keep travelers, airport employees and others updated. ADOT always advises motorists to check traffic conditions before using the highway system, and to allow extra time when traveling through construction zones because delays are possible.

  • What does ADOT take into consideration when planning highway closures?

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    ADOT carefully plans project-related freeway closures. For example, ADOT does not schedule closures that will impact drivers during peak travel times on weekdays or in conflict with large special events or major holidays. The project team will also coordinate with other ADOT project teams to avoid multiple freeway closures at the same time whenever possible. Unplanned closures or restrictions may occur because of unexpected situations or emergencies. ADOT will provide information as quickly as possible under these circumstances.

  • Is ADOT identifying alternate routes for motorists to use during closures and restrictions?

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    Yes. ADOT is working with the Maricopa Association of Governments and the Developer to study traffic patterns and identify the best potential alternate routes for motorists to use when construction requires freeway closures and restrictions. ADOT is also collaborating with the cities of Phoenix, Tempe, Chandler and the town of Guadalupe to determine how detour routes might impact their streets. ADOT will provide approved detour routes in advance of highway closures or restrictions.

How to Get Information About the Project to Stay #AheadOfTheCurve

  • How do I find more project information, ask questions and provide comments before and during construction?

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    ADOT is providing many ways for everyone to stay #AheadOfTheCurve, ask questions and provide comments:


    You’re also welcome to stop by the project office at 3157 E. Elwood St., Suite 100, Phoenix 85034 between 8 a.m. and 5 p.m. Mondays-Fridays (except holidays).

    ADOT is also running an advertising campaign for the life of the project, and will share information with traditional, Latino and Native American news media.