SR 89 - SR 179 Sedona Slip Lanes

Project Overview

The Arizona Department of Transportation, in partnership with the city of Sedona, is in the final design phase of the Sedona Slip Lanes project that will create enhancements for the roundabout at the intersection of State Route 89A and State Route 179 in Sedona.

One of the enhancements will be a bypass right-turn lane (slip lane) for the west approach, from northbound SR 89A to southbound SR 179. The other enhancement will be a dedicated right-turn lane for the south approach, from northbound SR 179 to northbound SR 89A. These modifications to the roundabout are designed to enhance safety and improve mobility through this high-traffic area.

August 2020 Update

This is a monthly update from the Arizona Department of Transportation and city of Sedona to nearby businesses and other stakeholders on the progress of the State Route 89A & State Route 179 intersection improvement design project.

The purpose of the ADOT intersection project – jointly funded by ADOT and the city – is to improve traffic operations and reduce congestion in the roundabout at the intersection of SR 89A and SR 179.

A major component of the project is providing operational improvements to the existing roundabout through the use of “slip lanes” at the intersection. The slip lanes would be used by drivers coming from West Sedona and making a right on SR 179, as well as drivers coming from I-17 or the Village of Oak Creek and making a right onto SR 89A towards Uptown. 

The slip lanes were originally identified as operational improvements to the roundabout in the City of Sedona Transportation Master Plan, approved in January 2018.

After initiating the project design last summer and conducting a further review of the project, the proposed design of the intersection has been modified to ensure the project delivers the expected improvements to current traffic conditions at the roundabout.

While a full slip lane for drivers coming from west Sedona and making a right on SR 179 is still being evaluated, a dedicated right-turn lane is now being evaluated in lieu of a full slip lane from SR 179 to SR 89A toward Uptown.

The two-month test began in May and ended in early July. The roadway test configuration created a dedicated right-turn lane from northbound SR 179 to northbound SR 89A. In addition, the eastern side of the roundabout was narrowed to one circulating lane, similar to the western side. This configuration will remain in place for the time being. Please see attached graphic showing the roadway configuration.

Update: The project team is currently completing the data analysis and will soon have a determination on whether the revised design option will improve travel times for drivers using the roundabout.

To date, the project team has completed the scoping process, developed the modeling criteria, re-evaluated the project design, proposed the above-mentioned design solutions, completed data recording of testing on a portion of the new proposed design and expects to make a recommendation in early October, after the analysis is completed. Originally, the project team was scheduled to make this recommendation in mid-summer but this date was pushed back due to refinements in the data analysis and modeling.

In addition, the project team is planning to host a meeting with stakeholders in late summer or early fall to review the final draft design plans. It has not yet been determined whether this meeting will be in-person or “virtual,” due to the current public health situation.

The design phase of the SR 89A & SR 179 intersection improvement project is scheduled to be completed in late spring 2021. Construction of permanent modifications to the roundabout is expected to begin in summer 2021.

July 2020 Update

This is a monthly update from the Arizona Department of Transportation and city of Sedona to nearby businesses and other stakeholders on the progress of the State Route 89A & State Route 179 intersection improvement design project.

The purpose of the ADOT intersection project – jointly funded by ADOT and the city – is to improve traffic operations and reduce congestion in the roundabout at the intersection of SR 89A and SR 179.

A major component of the project is providing operational improvements to the existing roundabout through the use of “slip lanes” at the intersection. The slip lanes would be used by drivers coming from West Sedona and making a right on SR 179, as well as drivers coming from I-17 or the Village of Oak Creek and making a right onto SR 89A towards Uptown.

The slip lanes were originally identified as operational improvements to the roundabout in the City of Sedona Transportation Master Plan, approved in January 2018.

After initiating the project design last summer and conducting a further review of the project, the proposed design of the intersection has been modified to ensure the project delivers the expected improvements to current traffic conditions at the roundabout.

While a full slip lane for drivers coming from west Sedona and making a right on SR 179 is still being evaluated, a dedicated right-turn lane is now being evaluated in lieu of a full slip lane from SR 179 to SR 89A toward Uptown.

Update: The two-month test began in May and ended in early July. The roadway test configuration created a dedicated right-turn lane from northbound SR 179 to northbound SR 89A. In addition, the eastern side of the roundabout was narrowed to one circulating lane, similar to the western side. This configuration will remain in place for the time being. Please see attached graphic showing the roadway configuration. With the testing period now completed, the project team is currently compiling the test data to evaluate the effectiveness of the temporary roadway configuration on queuing times of vehicles waiting to enter the roundabout, peak flows, delays/congestion, turning movements, etc.

The project team will use this data to help determine whether the revised design option will improve travel times for drivers using the roundabout and expects to make a recommendation in mid-summer after the analysis is completed.

To date, the project team has completed the scoping process, developed the modeling criteria, re-evaluated the project design, proposed the above-mentioned design solutions and has completed data recording of testing on a portion of the new proposed design.

In addition, the project team is planning to host a meeting with stakeholders in late summer or early fall to review the final draft design plans. It has not yet been determined whether this meeting will be in-person or “virtual,” due to the current public health situation.

The design phase of the SR 89A & SR 179 intersection improvement project is scheduled to be completed in late spring 2021. Construction of permanent modifications to the roundabout is expected to begin in summer 2021.

    Project Area Map

    Sedona Slip Lanes Project Map

    Stakeholder Updates

     

    The scope of this project will include: 

    • Constructing a slip lane and a dedicated right-turn lane.
    • Installing raised medians, pedestrian lighting and sidewalks and sidewalk ramps.
    • Relocating utilities, as needed.

    About the Project

    The purpose of the ADOT project – jointly funded by ADOT and the city of Sedona – is to improve traffic operations and reduce congestion in the roundabout at the intersection of SR 89A and SR 179. 

    A major component of the project is incorporating the use of a “slip lane” at the intersection for northbound drivers on State Route 89A. The slip lane was originally identified as an operational improvement to the roundabout in the City of Sedona Transportation Master Plan, approved in January 2018.

    The slip lane will enable northbound SR 89A drivers to make right turns onto southbound SR 179 – and go around or “slip” through the intersection – without conflicting with traffic in the roundabout. 

    After initiating the project design last summer and conducting a further review of the project, the proposed design of the intersection was modified to ensure the project delivers the expected improvements to current traffic conditions at the roundabout.

    While a full slip lane for drivers coming from west Sedona and making a right onto southbound SR 179 is still being evaluated, a dedicated right-turn lane is now being tested and evaluated in lieu of a full slip lane from SR 179 to SR 89A toward Uptown.

    This test, through modifying the existing striping configuration, has temporarily created a dedicated right-turn lane from northbound SR 179 to northbound SR 89A. In addition, the eastern side of the roundabout was narrowed to one circulating lane, similar to the western side.

    Sedona Slip Lanes Test Map

    The current test configuration will help determine whether the revised design option will improve travel times for drivers using the roundabout. The two-month test period is scheduled to end in early July.

    The two-month test period began in May and ended after the Independence Day holiday weekend in July. The project team is currently collecting the test data, which will assist in evaluating the effectiveness of the slip lane from West Sedona by studying queuing times of vehicles waiting to enter the roundabout, peak flows, delays/congestion, turning movements, etc. 

    The team is processing the data over the next several weeks and will make a recommendation in mid-summer after the analysis is completed.

    To date, the project team has completed the scoping process, developed the modeling criteria, re-evaluated the project design, proposed the above-mentioned design solutions and is currently testing a portion of the new proposed design. 
     

    Project Schedule

    • Final Design – Currently underway through early 2021
    • Construction – Summer 2021

    Schedule subject to change based on weather or other unforeseen factors.

    Stay Informed!

    ADOT welcomes your questions and comments. Please contact us in any of these ways:

    • By email: Subscribe to receive project updates and traffic alerts.
    • By phone:  Call the ADOT Bilingual Project Information Line at 855.712.8530.
    • Online: Submit a question or comment through the ADOT website. Visit azdot.gov/Contact and then select Projects from the dropdown menu.
    • By mail:  Write to ADOT Community Relations, 1655 W. Jackson St., MD 126F, Phoenix, AZ 85007