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Idaho 75, Elkhorn Road to River Street

The Idaho Transportation Department is developing plans to improve capacity and safety on Idaho 75 between Elkhorn Road and River Street in Ketchum.

Idaho 75 is the primary north-south highway in the Wood River Valley serving the cities of Bellevue, Hailey, Ketchum, and Sun Valley in Blaine County.

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Project Update - Fall 2023

The team is working to finalize design plans, acquire necessary property and prepare for construction. ITD plans to hold another community discussion next year to share more information about next steps in the project.

To watch a video summarizing the outcomes from our last community discussion, please click here.

Background

Several years ago, ITD studied potential improvements to Idaho 75 between the Timmerman Junction (at US 20) and Ketchum. This study was documented in the 2008, SH-75 Timmerman to Ketchum Environmental Impact Statement and Record of Decision.

The Idaho 75, Elkhorn Road to River Street project will be the third project based on this study.

What this project includes

ITD is re-evaluating the project identified in the 2008 Record of Decision /Environmental Impact Statement. This process will determine if corridor conditions or regulatory policies have changed that would affect the design of the project.

Work will include:

  • Updating traffic projections through 2047 (design year).
  • Evaluating current corridor conditions, regulatory policies and the 2008 concept design.
  • Developing preliminary design plans for improving the roadway and Trail Creek Bridge.
  • Determining how the proposed designs would affect the human and natural environment along the corridor.
  • Working with the community.
  • Completing final design plans for construction.

Public Involvement

Public involvement is important to ITD and the success of the project. ITD will ask for the community’s input throughout the project. Opportunities for participation include community working groups, public meetings and stakeholder interviews.

ITD hosted community discussions in June 2020, June 2021 and Oct. 2022 to gather comments about this project. Please visit the Downloads and Resources section to review materials from either discussion.

2019 –2020
Collect field data and begin technical studies. Begin environmental reevaluation. Evaluate/confirm 2008 concept design. Identify proposed improvement options. Public involvement.
2020 –2021
Evaluate options and complete environmental reevaluation. Prepare preliminary design plans. Public involvement.
2022-2023
Prepare design plans. Public involvement. Finalize environmental review and proposed improvements. Right-of-way acquisition. Acquire permitting.
2025 - 2026
Begin construction.
Frequently Asked Questions
You've got questions, we've got answers! Here are some of the most common questions we've received about this project.
Construction
How soon will construction begin?
How soon will construction begin?

Construction is currently funded to begin in late 2025.

Construction
Is ITD coordinating highway construction with Idaho Power’s transmission line project? Can existing overhead powerlines also be buried at this time? If so, where will they be buried?
Is ITD coordinating highway construction with Idaho Power’s transmission line project? Can existing overhead powerlines also be buried at this time? If so, where will they be buried?

ITD is coordinating with Idaho Power on their new transmission line project; however, the two projects may have different construction schedules. Idaho Power and the City of Ketchum are working to determine if the existing overhead power lines could be buried. ITD is working with utility owners to determine the final locations for all utilities in the corridor.

Design plans
Can ITD alter aspects of the 2021 concept designs?
Can ITD alter aspects of the 2021 concept designs?

Any alterations to the current designs would need to fall within the framework of the 2008 Final Environmental Impact Statement (FEIS). For example, it would be difficult to reduce the number of through lanes proposed in the 2008 FEIS. ITD has found that traffic demands today are similar to or higher than what was projected in the 2008 FEIS. We will present any changes to the public prior to completion of the final plans.

Design plans
Does this project include improvements to the River Street intersection?
Does this project include improvements to the River Street intersection?

No, this project does not include improvements to the River Street intersection.

General
Why is ITD moving forward with a traffic signal at the Serenade Lane intersection? What is the data that supports a signal?
Why is ITD moving forward with a traffic signal at the Serenade Lane intersection? What is the data that supports a signal?

Throughout this project, ITD has analyzed traffic data and other technical work while keeping the intent of the 2008 Environmental Impact Statement/Record of Decision in mind.

A traffic analysis was conducted that evaluated a stop-controlled intersection, a signalized intersection and a roundabout intersection at the Serenade Lane intersection. The analysis indicated:

  • a signalized intersection would operate at LOS* (Level of Service) C in 2025 and LOS D in 2047 with an average delay of 53 seconds per vehicle.
  • a roundabout would operate at LOS B in 2025 and LOS F in 2047 with an average delay of 111 seconds per vehicle.
  • a stop-controlled intersection would operate at LOS E in year 2025 and LOS F in the future year 2047, with very long delays and no gaps at all for the eastbound left turn.

*LOS = Level of Service: Level of service (LOS) is a term used to describe the operating conditions of a roadway based on factors such as speed, travel time, maneuverability, and delay.  Level of service is divided into six letter grades, “A” through “F,” with “A” being the best and “F” being the worst. Intersections typically must operate at a LOS D or better to be acceptable. LOS D is the point where delays become more noticeable to drivers and backups occur.

Based on the traffic analysis and other technical information, ITD has decided to move forward with a traffic signal at the Serenade Lane intersection for several reasons including:

  • better long-term operations with less delay time as traffic volumes increase.
  • it’s more familiar to drivers in this region.
  • it’s easier for large trucks to maneuver through.
  • will include a stop-controlled signal crossing for bikes and pedestrians crossing Idaho 75 and Serenade Lane.
  • will provide gaps in traffic for vehicles pulling onto Idaho 75 from driveways and side roads.
  • will have less right-of-way acquisition and lower construction costs.
  • will be easier to maintain in winter weather.
General
Will widening the highway increase congestion in Ketchum?
Will widening the highway increase congestion in Ketchum?

Many vehicles use Idaho 75 today, with even more expected to use the road in future years. Obviously, there is congestion in the corridor today with the worst congestion occurring during peak travel periods. Congestion can be expected to continue as the Wood River Valley grows, and this will be true even after Idaho 75 is widened.

ITD and the Federal Highway Administration are obligated to improve our transportation system to meet the needs of the future.  Improvements cannot just address congestion, but they must also balance safety, access, multi-modal travel, and consider the local context and community input.  The EIS/ROD proposed improvements include widening SH-75 to two through lanes in each direction from the south up to Serenade Lane, but only one lane was proposed in each direction north of Serenade Lane.  This decision was made in 2008 based on the community’s request to retain the character of Idaho 75 entering the Ketchum urban area.  ITD recently heard from many community members that this request still exists, while others indicated an interest in reducing congestion with more lanes.

When the improvements are made to widen SH-75, we expect some of the current northbound congestion north of Elkhorn Road to move north and closer to town.  We do not expect the proposed improvements to significantly change congestion that occurs in the main downtown city urban area.

General
How does widening the road impact speeding?
How does widening the road impact speeding?

The speed limit on Idaho 75 is currently 45 mph from Hospital Drive to Elkhorn Road and 35 mph from Elkhorn Road to Gem Street. Based on the EIS/ROD and as a part of this project, ITD intends to post the speed limit at 35 mph from Hospital Drive to Serenade Lane, and 25 mph from Serenade Lane to River Street.  Based on ITD’s standard practice, a speed study will be conducted sometime after the project is completed. ITD could adjust speed limits at that time based on the 85th percentile speeds (speed at or below which 85 percent of drivers will operate).

Many community members have commented that speeds are too high in the corridor and many drivers exceed the posted speed limit.  While it is difficult to predict driver behavior and determine exactly how speeds will change once the project is completed, it is known that most motorists drive at speeds that are comfortable based on the prevailing conditions.  Higher traffic volumes, road features such as narrow lanes, and the use of curbs or other objects placed close to the roadway tend to slow speeds.

The proposed road is a 4-lane road, with 11-ft lanes and no center turn lane or shoulders. Curb will be used on both sides of the road. It is expected that motorists will experience a more constrained feel when traveling on Idaho 75, which should prevent speeds from increasing.

General
Is there a longer-term plan to have four lanes from Serenade to River Street? Why is the bridge only being striped for three lanes initially?
Is there a longer-term plan to have four lanes from Serenade to River Street? Why is the bridge only being striped for three lanes initially?

The proposed improvements in the 2008 Environmental Impact Statement/Record of Decision include constructing a 3-lane roadway between Serenade Lane and River Street with the new Trail Creek bridge wide enough for 4 lanes, although it would be striped for 3 lanes initially.  It is common for ITD to build bridges wider to accommodate future improvements since they are designed for a 75-year life cycle.

The decision in the 2008 Environmental Impact Statement (EIS) and Record of Decision (ROD) was made based on coordination with the city and other stakeholders who preferred the 3-lane section. ITD is continuing with the 3-lane section for the following reasons:

  • many stakeholders still prefer the 3-lane option in this area.
  • the 3-lane section allows for a center turn lane which will facilitate turning in and out of side roads and driveway approaches (a five-lane section will not fit in this area).
  • many vehicles use Serenade Lane and 2nd or 3rd Avenue as a back route into the city.
  • the new curb will be constructed 3-ft wider on each side when compared to the proposed EIS design. This will allow ITD and the city to change Idaho 75 to a 4-lane road in the future by only changing the pavement markings.
General
How is ITD going to address public comments?
How is ITD going to address public comments?

Each comment is reviewed by ITD and members of the design team.  While every comment is carefully considered, it is of course not possible to make design changes that will satisfy everyone’s requests. This is particularly true since many comments we receive are in conflict with one another.

Please know that your comments do matter.  We will be in constant contact with the community with more details on improvement plans and an invitation to the next community discussion.

General
What is the plan for snow removal?
What is the plan for snow removal?

Snow removal in the Wood River Valley is a critical and challenging task. ITD is responsible for clearing snow off Idaho 75 as a part of maintaining the state highway system. The local jurisdiction is responsible for clearing snow off sidewalks, which is often delegated to property owners by ordinance.

The challenge for property owners is to keep private driveways clear and accessible during and after a snow storm. Unfortunately, it is almost impossible for the snowplow driver to raise the blade in front of the hundreds of driveways and approaches along Idaho 75. Stopping to do this would cause backups and safety issues.

ITD’s road maintenance crew will evaluate the best way to keep Idaho 75 open and clear in the winter once construction is complete.

General
Does ITD need to purchase property to make identified improvements for this project?
Does ITD need to purchase property to make identified improvements for this project?

Yes, ITD has been in contact with several property owners along the corridor about project impacts and possible right-of-way acquisitions for this project. These meetings will continue with acquisition procedures beginning this year.

General
Where will people park?
Where will people park?

During community outreach, ITD heard from many stakeholders that the existing street parking in Segment C should be retained. ITD has made changes to the original Environmental Impact Statement/Record of Decision design layout so that most of the on-street parking in this area will be retained. The new on-street parallel parking will be 8-ft wide, consistent with city standards, and will be located adjacent to the 5-ft bike lane. Final design plans will be presented to the public before construction begins.

General
What is the role of the Federal Highway Administration in this project?
What is the role of the Federal Highway Administration in this project?

This project is a continuation of the Federal Highway Administration (FHWA) National Environmental Policy Act (NEPA) process that led to the Final Environmental Impact Statement and Record of Decision (FEIS/ROD). The process looks at all key points to determine whether the NEPA document, the determinations, and final decisions remain valid for continued action. ITD is working closely with FHWA to make sure the project follows all federal requirements and laws. Additionally, any changes to the 2008 FEIS/ROD need to be approved by FHWA through the re-evaluation process.

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