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Transportation planning

Transportation planning

Congestion and safety management

Public Works administers a congestion and safety management system commonly referred to as concurrency.

Program update - June 2014
Clark County proposes to change its concurrency approach.

Public Works provides a variety of services related to concurrency, including:

  • Reviewing development requests for congestion and safety management, including modeling traffic conditions, requiring traffic improvements (mitigation) and crafting policy and ordinance changes.
  • Negotiating and administering development agreements, including frontage and off-site improvements, reserving future road capacity (trips) and related issues.
  • Researching projects and crafting programs, including putting together a program for projecting future accident probability for new development based on actual crash history, correlated with intersection geometry and traffic volumes.

Concurrency evaluations

Subdivisions, short plats, site plans and conditional use permits are subject to concurrency evaluation as part of the development review process.

Computer modeling can be used to assess the effect a project would have on traffic congestion, taking into account other developments that have been approved but not yet built and transportation improvements that have been funded but not yet constructed.

The county currently uses a corridor approach to manage congestion (see "Program update" at the top of this page). Afternoon peak hour travel speeds cannot dip below an established miles per hour standard, or "level of service" for that corridor.

Small projects

Development requests that would create fewer than 10 afternoon peak hour trips only need to submit a traffic profile form (PDF). Typically, no professional assistance is required to complete this form. Please submit this form as part of your land use application to Clark County Community Development.

Large projects

Professional assistance from a traffic engineer is usually necessary for projects that would create 10 or more afternoon peak hour trips because a traffic study will be required. The county requires traffic studies to have a professional engineer stamp to be accepted. Your engineer can find more information from the administrative manual (PDF 4.5MB).


A congestion management program has been required since the Washington Legislature passed the Growth Management Act in 1990. Under state law, roads must be able to handle traffic created by a new development for that project to receive approval.

Specifically, the law states that "local jurisdictions must adopt and enforce ordinances which prohibit development approval if the development causes the level of service on a locally owned transportation facility to decline below the standards adopted in the transportation element of the comprehensive plan."

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