Mercer Island Comprehensive Plan

Mercer Island’s Comprehensive Plan, of which the Transportation Element is a part, must be internally consistent. This means that the various requirements of the various elements may not contradict one another. Of particular importance is the relationship between the Transportation Element and the Land Use Element.

The Land Use Element defines Mercer Island’s strategy for managing growth and physical land development for the next 20 years. 1990 population was just under 21,000. Mercer Island expects to reach its “maximum” population capacity at 25,000 people, likely within the next 20 years. The traffic forecasts developed as part of this transportation element are consistent with this rate of population growth.

Proposed transportation improvements, policies and programs are also consistent with the vision of the Land Use Element. The land use vision emphasizes reorientation of development in the central business district area to create a true “town center.” Most of the forecast housing units needed to accommodate additional population will be located in and around the downtown core. The lower density residential nature of the remainder of the island will be maintained.

King County Countywide Planning Services

The Growth Management Act of 1990 (GMA) and 1991 Amendments mandate that policies developed by jurisdictions participating in the comprehensive planning process be coordinated. This coordination occurs at several levels. First, counties are to set overall planning policies to guide policy development and implementation in all jurisdictions within the county. Second, these “countywide planning policies” are to be coordinated with similar policies developed in adjacent counties through a set of “multi-county planning policies.” Third, local jurisdictions’ policies must conform to the requirements of countywide and multi-county planning policies.

All of these requirements mean that Mercer Island’s transportation policies should not conflict with the policies of the region or adjacent local jurisdictions. Where conflicts exist, GMA encourages informal coordination between jurisdictions, and provides formal mechanisms for resolving inconsistencies through Growth Management Hearings Boards.

Mercer Island’s proposed transportation policies are fully consistent with King County’s countywide and multi-county planning policies. Major policy areas addressed by the countywide policies include provisions for high capacity transit, non-motorized modes, road system mobility maintenance, level of service, updating plans, transportation financing, the State’s role in providing transportation facilities and services, and siting regional and countywide facilities.

However, the application of Policy T-10 to Mercer Island needs further discussion. Policy T-10 requires that local jurisdictions establish “mode split” goals (for serving more trips by transit, HOV, and other non single occupant vehicles). The mode split goals developed for Mercer Island by the PSRC appear to be too optimistic.

In 1990, 86.5 percent of work trips destined for Mercer Island were made by single occupant vehicle (SOV). A little over 13 percent were made by HOV, and about 0.2 percent were made by transit. The PSRC forecasts for 2010, which take into account the potential effects of CTR efforts, indicate that SOV trips will account for 77.7 percent, and that carpools and transit will serve about 18 percent and about 4.3 percent respectively.

Mercer Island would like the PSRC to revise these forecasts for the following reasons. First, work trips to Mercer Island are relatively insignificant when compared to work trips from Mercer Island. The island has very few employers. Achievement of higher transit and carpool shares should be focused on the large number of commute trips made off-island.

Vision 2020

Vision 2020 articulates a coordinated long-range land use and transportation growth strategy for the Puget Sound region. It combines a public commitment to a growth vision with the transportation investments and programs needed to support that vision. Vision 2020 calls for the containment of growth, limiting the extent of sprawl into surrounding farmlands, forests and open spaces. It concentrates new employment in one regional center (Seattle), five metropolitan centers (Bellevue, Bremerton, Everett, Renton and Tacoma), and several sub regional centers. The concept connects the centers with a regional rapid transit system. Areas outside of the centers are classified as activity clusters, pedestrian pockets and small towns.

The central business area of Mercer Island is classified as an activity cluster. The island is not a focus of regional growth, but may still accommodate some population growth, especially in the activity cluster area. Vision 2020 envisions this area as an area of mixed-use employment and housing, with a pedestrian focus. Local transit services would link the island’s neighborhoods with the regional transit system. Express transit service would be provided between the activity cluster area (the downtown) and regional centers. Commuter parking could also be provided to enhance transit ridership.

Net residential density is envisioned to average about 12 dwelling units per acre in the central business area, and about six units per acre around the rest of the island. Employment would focus on serving the needs of the island’s residents; major employment concentrations are not envisioned for Mercer Island.

Mercer Island Comprehensive Plan’s Land Use Element supports this concept of how Mercer Island fits into the regional growth strategy. The focus of the Comprehensive Plan on downtown area development and minimizing growth in existing residential areas mirrors Vision 2020’s concept for Mercer Island. Further, the transportation element of the Comprehensive Plan directly supports Mercer Island’s land use vision, and is therefore consistent with Vision 2020.

Metropolitan Transportation Plan

The Puget Sound Regional Council (PSRC) is currently developing a Metropolitan Transportation Plan (MTP) to implement Vision 2020. This plan, as an outgrowth of Vision 2020, will replace the 1982 Regional Transportation Plan as the basis for approval of state and federal transportation expenditures in the region.

The MTP is being development in strict conformance with the policy and conceptual direction of Vision 2020. Therefore, Mercer Island’s Comprehensive Plan Transportation Element will be consistent with the MTP since both will be consistent with Vision 2020.

Regional Transit System Plan

The Regional Transit System Plan (RTP) lays out the Puget Sound region’s plans for constructing and operating a regional high capacity transit system. The RTP is an outgrowth of Vision 2020, meant to address the public transportation element of that regional plan. The current plan, endorsed by the region’s elected officials, calls for a regional rapid rail system and supporting commuter rail, regional bus, and local transit services. A Regional Transit Authority (RTA) has been appointed by the governing bodies of the participating counties (King, Snohomish and Pierce) to oversee detailed system planning and development, obtain financing, and construct, operate and maintain the system. The RTA is currently revising the System Plan to reflect recent changes in preparation for a public vote to approve or disapprove new tax measures to fund the system.

Mercer Island will be directly affected by the regional transit system. Interstate 90, which crosses the north end of Mercer Island, is proposed as a main east-west HCT corridor. Rapid rail and increased regional bus services would operate in this corridor, and Mercer Island would be served by a major rail station near the downtown area.

The City of Mercer Island has actively participated in RTP planning from its inception. Both land use and transportation plans for Mercer Island directly support development of regional transit service and facilities, and are consistent with the regional public transportation vision that will be implemented by the RTP.

METRO Long Range Plan For Public Transportation

The King County Department of Metropolitan Services (Metro) has prepared a long range public transportation plan for King County that details service concepts for local areas within the county. The plan was developed in coordination with the Regional Transit Project to reflect the supporting service concepts of the regional transit system. However, the Long Range Policy Framework for Public Transportation goes beyond support for the RTP, and details local area service concepts based on current and future transit needs.

The long range plan calls for:

•    access to the regional rail system at a station located at I-90 and 77th/80th Streets;

•    primary service focus at the rail station;

•    expanded local route service periods and increased frequencies;

•    expanded demand response services for the island’s special needs population;

•    increase peak hour service frequencies;

•    construction of a bus transfer facility at the rail station;

•    improved pedestrian facilities along transit routes;

•    expanded park and ride capacity to meet both local and regional needs;

•    provision of bicycle facilities at park and ride lots; and

•    consideration of smaller buses for neighborhood feeder service.

Metro’s service concept for Mercer Island and overall policy framework are consistent with the policies and recommendations of Mercer Island Comprehensive Plan Transportation Element. However, Mercer Island’s plan stresses demand response service more than Metro’s plan does. This issue can be worked out between the jurisdictions as service changes are considered and implemented.


Growth Management

The Growth Management Act, enacted by the Washington State Legislature in 1990 and amended in 1991, requires urbanized counties and cities in Washington to plan for orderly growth for 20 years into the future. The Act has a number of requirements, including a set of mandatory “elements” that must be included in each jurisdiction’s comprehensive plan. One of the mandatory elements is a comprehensive transportation plan that supports and is supported by the land use element.

Mercer Island’s transportation element conforms to all of the components of a comprehensive transportation element as defined by GMA, including:

•    land use assumptions used in estimating future travel;

•    inventories of air, water and land transportation facilities and services;

•    level of service standards for arterials and transit routes;

•    specific actions for bringing into compliance any facilities or services that are below

•    adopted level of service standards;

•    ten year forecasts of traffic based on the land use plan;

•    identification of system expansion needs and transportation system management needs to

•    meet current and future demands;

•    an analysis of funding capability to judge needs against probable funding resources;

•    a multi-year financing plan based on identified needs;

•    identification of intergovernmental coordination efforts and consistency with other plans; and

•    demand management strategies

Commute Trip Reduction

In 1991, the Washington State Legislature enacted the Commute Trip Reduction Law. The law requires implementation of transportation demand management (TDM) programs to reduce work trips. The law requires employers with 100 or more employees at a single site to develop and implement ways to reduce the number of work trips made to the site by employees using single occupant vehicles. Specifically, the law requires that vehicle miles traveled (VMT) related to work trips be reduced 15 percent by 1995, 25 percent by 1997, and 35 percent by 1999.

In response to these requirements, Mercer Island has developed its own CTR program to reduce work trips by City employees. There are two other affected employers on the island; both have developed CTR programs.

Air Quality Conformity

Amendments to the federal Clean Air Act made in 1990 require states with areas that exceed national ambient air quality standards for ozone and carbon monoxide to develop plans for each area that, when implemented, will reduce air pollutants so that standards may be attained. These attainment plans must be adopted by the state and submitted to the Environmental Protection Agency (EPA) as amendments to the State Implementation Plan (SIP). The Central Puget Sound area, including King County and Mercer Island, are currently designated as “non-attainment” areas for both ozone and carbon monoxide.

Air quality attainment is a regional process. A combined effort of state agencies, the Puget Sound Air Quality Control Agency (PSAPCA), and the Puget Sound Regional Council (PSRC) has resulted in attainment plans for both pollutants. Mercer Island, as a member of the PSRC, has agreed to assist in implementation of the SIPs at the local level to help achieve regional air quality standards. Key elements of the SIPs are:

•    emission inventories;

•    expanded and enhanced vehicle inspection and maintenance programs;

•    oxygenated fuel program;

•    forecasts and methods for tracking vehicle miles traveled;

•    contingency measures if the Puget Sound area exceeds forecast vehicle miles traveled;

•    reporting requirements for point sources of volatile organic compounds and nitrogen oxide;

•    an interagency coordination process for identifying transportation control measures (TCMs);

•    demonstration of carbon monoxide standard attainment by 1995;

•    contingency measures for failure to attain the ozone and carbon monoxide standards by statutory deadlines;

•    revisions to rules for major new sources; and

•    regulations to require conformity of transportation plans and projects with adopted air quality standards and the SIP.

In most cases, implementation of required control strategies is presumed to be all that will be needed to attain standards. However, for carbon monoxide, the Central Puget Sound region must demonstrate that adopted TCMs will be sufficient to attain standards. Preliminary modeling results indicate that the prescribed measures should provide sufficient emission reductions to achieve attainment.

The plans, programs and projects included in this transportation element of the Mercer Island Comprehensive Plan are consistent with the requirements of the Central Puget Sound SIPs for ozone and carbon monoxide.