Juneau Egan-Vanderbilt Continuous Green T Intersection

Project # SFHWY00524

 

The Alaska Department of Transportation and Public Facilities (DOT&PF) is proposing to convert the existing signalized intersection at Egan Drive and Vanderbilt Hill Road in Juneau, Alaska into a Continuous Green T (CGT) signalized intersection. A CGT signalized intersection allows free-flow movement of through-traffic lanes along the top of the T, while the other lanes remain signalized for movements through the intersection.

The proposed project would:

• Modify the traffic signals on Egan Drive southbound, converting these traffic lanes to “continuous green” free-flow movements through the intersection
• Construct an acceleration lane on Egan Drive southbound for merging left-turn traffic from Vanderbilt Hill Road
• Widen the left-turn lane at the intersection on Egan Drive southbound to provide a 6-foot painted median safety buffer to the adjacent “continuous green” traffic lane
• Construct a raised median in the intersection to guide left-turn traffic from Vanderbilt Hill Road merging onto the new acceleration lane on Egan Drive southbound
• Construct a raised median and remove a left-turn lane on Vanderbilt Hill Road, to align with the single lane left-turn onto Egan Drive southbound
• Realign the traffic signal on the mast arm for Vanderbilt Hill Road with the single left-turn lane
• Modify existing storm drain system in the vegetated median

The existing and proposed site layouts can be viewed here.

Project History

The Egan Drive and Vanderbilt Hill Road intersection is a key part of the traffic circulation in the Lemon Creek area for a high number of residents and is the primary route for commercial traffic to and from the Lemon Creek industrial area. This 3-way “T” intersection has a history of elevated crash rates related to signalized turning movements across the major traffic lanes on Egan Drive.

The Southcoast DOT&PF Traffic Section evaluated several safety improvements, and a CGT design concept appears to offer enhanced traffic and safety benefits over the existing configuration.

This project is intended to reduce the incidence of rear‐end, angle, and sideswipe crashes for the southbound Egan thru lanes by converting them to continuous green lanes with no conflicting movements. Reductions to crashes in the northbound Egan direction may also result since the traffic signal controller will be better able to optimize for gaps, considering one direction of traffic instead of two. Thereby reducing the number of vehicles forced into the dilemma zone during signal max‐outs.

In addition, the existing southbound left‐turn and new southbound median acceleration lane will be buffered slightly from the southbound thru lanes reducing the incidence of sideswipe crashes between the movements. A mountable raised concrete median will be installed in this buffer space to aid delineation. The benefits of a CGT to this intersection are as follows:

• Improved Safety: Channelization of left-turn vehicles from Vanderbilt Hill Road will reduce the potential for angle crashes
• Free-flow in one direction: Travel on Egan Drive southbound never stops, which improves traffic signal synchronization and reduces corridor travel times.
• Increased Efficiency: With Egan Drive through lanes in “continuous green” free-flow, more green time can be provided to the other signalized turning movements – reducing delays at the intersection

The project was nominated by the region for funding through the Statewide HSIP (Highway Safety Improvement Program). All submitted HSIP projects are scored by the State Traffic & Safety Office, and funded in order of their likelihood to eliminate or minimize serious crashes and fatalities. This project was successfully awarded HSIP funds with design in FY24-25 and construction slated for FY26.

If you have questions and/or would like to submit comments, please contact the project team or fill out the comment form.

---

The environmental review, consultation, and other actions required by applicable Federal environmental laws for this project are being, or have been, carried out by DOT&PF pursuant to 23 U.S.C. 327 and a Memorandum of Understanding dated April 13, 2023, and executed by FHWA and DOT&PF.