State Route 99/Eaton Road Interchange Improvement Project

Construction Completed Spring 2022

Image of completed project at night.

Project Description

This project converted State Route 99 (SR 99) North Bound (NB) ramps at Eaton Road and Hicks Lane into one multilane, five-leg roundabout intersection. Although the two intersections were combined, the local circulation and access remained unchanged.

The primary purpose of this project was to improve safety for all travel modes at the SR 99 NB ramp intersection and Hicks Lane intersection with Eaton Road. The secondary purpose of this project was to improve operations, reduce delay, and enhance mobility for all travel modes at the intersections.

Construction was phased in order to maintain local access to SR 99 and to the properties adjacent to Eaton Road and Hicks Lane.

Construction Detours

Beginning August 9, 2021 and continuing through early 2022, the following road closures and detours were in place.

Detour A

SR99/Eaton Northbound Off Ramp – Closed Monday – Friday evenings from 9pm to 6am

Detour B

SR99/Eaton Northbound On Ramp — Closed 100% day and night until further notice

Detour C

Eastbound Direction of Eaton Overcrossing — Closed Monday - Friday evenings from 9pm – 6am

Image of the project layout. The legend identifies areas of paved surface, truck apron, hard surfacing, landscape area, and sidewalk. The roundabout connects the following roadways: Hicks Lane from the north, Eaton Road from the east, north bound State Route 99 exit ramp from the south, Eaton Road from the southwest, and the State Route 99 north bound entrance ramp from the northwest.

Construction Details

Notification of Construction Activity


This project is funded with a combination of federal Highway Safety Improvement Program (HSIP) funds, State Highway Operation and Protection Program funds, and Local Agency match funds. Construction is estimated to cost approximately $5 million.

Public Outreach

Updated Road Closures - 12/6/2021

Press Release - Start of Construction

Eaton Newsletter - April 2019

Plans and Specifications


Bid Book

Project FAQs

Why build a roundabout at this intersection? The assessment of this project’s safety needs included an Intersection Control Evaluation, and professional analysis deduced that a traffic signal would not solve the current safety issues. In addition, it would increase the costs related to the project, as a traffic light would necessitate the widening of both the off-ramp and the Eaton Road Overcrossing. Also, to maintain safe traffic flows, a traffic signal would have ultimately required a closure of Hicks Lane.

Why was this project important to the City? This project was specifically identified as a safety project, meaning that there was an identified issue with traffic flow that needed to be addressed. The funding for this project was specific to the safety needs that have been identified. One of the components of this project included the grinding and resurfacing of Eaton Road within the construction area, which provides a smooth driving surface to motorists approaching and using the roundabout.

Environmental Clearance

CEQA Notice of Determination

NEPA Categorical Exclusion

Log in