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Flood Gate System Improves Road Closure Operations and Public Safety

Flood Gate System Improves Road Closure Operations and Public Safety

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Washington County, Oregon, is one of six member agencies of TransPort, a subcommittee of Portland Metro’s Transportation Policy Alternatives Committee (TPAC) that focuses on transportation system management and operations. Transportation systems engineers from Oregon DOT, Tri-County Metropolitan Transportation District of Oregon (TriMet), Clackamas County, Multnomah County, Washington County, and the City of Portland meet regularly to discuss regional planning for and investment in technologies to support efficient transportation as the members have overlapping responsibility for the road network within the region and want local projects to align with regional initiatives. Washington County, located west of the City of Portland is 726 square miles and had a 2010 population of 529,710.[i] The county’s urbanized areas are within the Portland Metropolitan Planning Organization’s planning area boundaries, but much of the rest of the county has a rural character. Land use within the county is a mix of urban development, agricultural land, floodplains, and forest. Much of the county is within the Tualatin Valley, surrounded by the Tualatin Mountains. Due to topography, Washington County’s roadways are affected by periodic flooding, particularly within the 100-year floodplain, and microclimate weather conditions that result in ice, fog, or snowy conditions.

Washington County developed an initial ITS plan in 2005 and updated the plan in 2013.[ii] In addition to Washington County department agencies, other regional ITS stakeholders include the City of Beaverton, City of Hillsboro, City of Sherwood, City of Tigard, City of Tualatin, Oregon DOT, Portland General Electric, TriMet, Tualatin Hills Parks & Recreation District, and Tualatin Valley Fire & Rescue. County planning projects that support rural ITS strategies within the purview of Washington County’s Traffic Engineering and Operations include a flood gate system, road weather information system, automated snow zone warnings, and speed feedback signage. Some of these ITS projects are still in development; however, the flood gate system is complete. Washington County’s flood gate system uses ITS sensors and cameras to assess flood conditions, with a goal of improved public safety and efficient deployment of county and first responder resources.

Project Purposes 

A segment of Fern Hill Road, located south of the City of Forest Grove, is a residential and commuter route that’s located in the 100-year floodplain and subject to flooding approximately six times per year. Prior to 2018, Washington County Maintenance and Operations staff, in coordination with the City of Forest Grove Fire and Rescue or Tualatin Valley Fire and Rescue, would pre-stage and place mobile barricades across Fern Hill Road and send staff to the field to visually check flooding status. When flooding receded, county staff would return to inspect the roadway for damage, clean the road surface, make any necessary repairs, and manually return signage and barricades to their staging area. The process was costly, time consuming, and posed a safety risk when members of the public chose to physically move the barricades or drive around to enter the closed roadway segment.

To address the ongoing issues, Washington County decided to install fixed, manually lockable gates, seen in Figure 8, that are supported by water depth sensors and surveillance cameras. Automated gates were considered; however, terrain constraints, the potential for flood damage, the need for maintenance staff to be able to assess road conditions, the need for emergency personnel to access the road when needed, and infrastructure costs were considerations that affected the decision to install manual gates. While the flood gates rely on county staff for the closing and opening process, what makes the system notable is the ITS component. With the new system, Washington County can monitor the gates and water levels through cameras and sensors without making multiple field visits to the gates. The real-time status information is then shared at both the county and state level through the county’s transportation information system and Oregon DOT’s TripCheck portal.

A Washington County Operations employee opens an arm of the Fern Hill flood gate. Image courtesy Washington County, Oregon.

The gate deployment process works through a series of steps. A U.S. Geological Survey stream gage field sensor alerts Washington County Operations when the gage height reaches 16.3 feet. Staff will monitor Fern Hill Road camera information for roadway conditions. When the stream gage reaches the high field sensor (16.5 feet), Washington County responds to the alert by closing the road segment. The flood gates, which include “Road Closed” signage and flashing red beacons, are manually locked. Pan-Tilt-Zoom cameras posted nearby enable real-time status checks of gate conditions and flooding levels. Gate position sensors transmit road closure information every five minutes to the TripCheck Traveler Information system, the county’s communication system, and information service providers such as Waze. Closure information is also shared with the public through, the county’s transportation information website, and social media.


Installation of the flood gate system required coordinated planning between the county’s separate Traffic and Operations and Maintenance departments. A portion of the road segment is bounded by Washington County’s Clean Water Services and the new flood gates are a technological update to an existing operations practice, so a traditional public involvement process was not used. The gates were installed in November 2017 and first used during the 2017 – 2018 winter season.[iii] Washington County Land Use and Transportation engineers report that the gates worked as projected during flooding. The gates were damaged during their first use by a vehicle driver determined to enter the roadway. The county crews were able to repair the damaged gates, and they had also prepared for this type of situation by ordering a second set of gates at the time that the system was installed.[iv]

The flood gate system, along with the county’s other planned rural ITS projects, serve the role of improving public awareness and safety, providing a means to monitor road conditions remotely, providing real-time condition information, and decreasing the staff time needed to open and close the roadways. As of March 2023, Washington County is in design for another flood gate system, similar in design to the Fern Hill system with minor changes informed by lessons learned about sensors and maintenance access, with hopes of construction in the coming fiscal year.[v]


The Fern Hill Road flood gate system, and its sister project on Susbauer Road, were county-initiated projects. Flood gate system repair and maintenance needs are addressed by the county’s overall Operations budget. In Washington County, Oregon, there are several funding program options for rural ITS projects including Gain Share revenues, a Major Streets Transportation Improvement Program (MSTIP) funded through county taxes, Metropolitan Transportation Improvement Program (MTIP) funds, federal Congestion Mitigation Air Quality (CMAQ) funding, and county road funds.

In the case of the Fern Hill flood gates, the system was funded through Gain Share, an Oregon-specific program. According to the Washington County Land Use and Transportation website, Gain Share funds consist of a share of the state income tax revenues generated from jobs creation related to Strategic Investment Program (SIP) agreements. SIP was created to attract job-producing companies by allowing local governments to negotiate alternative taxing agreements with businesses that agree to invest at least $100 million in an urban area or $25 million in a rural area in Oregon.[vi] The 2015 Oregon legislature capped the shared amount to $16 million annually for any participating county. The Washington County Board has decided to focus Gain Share funds on one-time projects rather than on-going projects or services.

For more information on Washington County’s ITS Plan and the Transportation Information website, visit

[i] U.S. Census Bureau (2018). Quick Facts,

[ii] Washington County, Oregon (2014). Washington County ITS Plan Executive Summary,

[iii] Washington County Oregon (2018). Fern Hill Road Closed Due to High Water; Gates in Place,

[iv] Personal communication with Stacy Shetler and John Fasana, October 2019

[v] Personal communication with John Fasana, March 2023

[vi] Washington County, Oregon (nd). Department of Land Use and Transportation: Gain Share Funding,

This report was delivered to the U.S. Department of Transportation in 2020. It was primarily authored by NADO Program Manager Rachel Beyerle and NADO Associate Director Carrie Kissel. Many transportation agency staff and others assisted with this project in a variety of ways. We offer deep and heartfelt thanks to all the individuals who have provided information and images, consented to be interviewed, and offered editorial guidance in support of this research. This work is supported by the U.S. Department of Transportation under requisition number HOIT190194PR. Any opinions, findings and conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of U.S. DOT or the NADO Research Foundation.

To read more about the report that contained this and other case studies, follow this link.

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