South King County High Capacity Transit Corridor Report. Figure Other Infrastructure

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1 South King County High Capacity Transit Corridor Report Figure Other Infrastructure 30

2 Shorelines and Critical Areas The corridor is framed by three major water bodies: Puget Sound to the west, Elliott Bay to the northwest, and Lake Washington to the northeast. Two major rivers present in the corridor are the Duwamish Waterway/Green River in Seattle and Tukwila, and the Cedar River in Renton. Major lakes include the reservoir at Westcrest Park and Lake Burien. The Washington State Shoreline Management Act restricts use of shorelines along marine waters and major streams, rivers, and lakes, which include those, listed above. All of the major waterways are also subject to the Shoreline Master Program requirements within each jurisdiction. The Washington State GMA requires jurisdictions to designate critical areas, which include wetlands, critical areas for recharging aquifers used for potable water, fish and wildlife habitat conservation areas, frequently flooded areas, and geologically hazardous areas. A large portion of the corridor is designated as a critical area, mostly related to flood plains and seismic/liquefaction risks. In general, these pose fewer development restrictions than others such as steep slopes, critical habitat, or wetlands. 4- Project Goals and Objectives The goals and objectives were developed to be consistent with Sound Transit s Long-Range Plan, the other HCT corridor studies, the PSRC Vision 2040 Plan, and other relevant Sound Transit policies. The goals and objectives of the study are outlined in Table 4-1. Goal Table 4-1. Project Goals and Objectives Objectives Provide a Transportation System that Facilitates Long- Term Mobility Enhance Communities and Protect the Environment Contribute to the Region s Economic Vitality Strengthen Communities Access to and Use of the Regional Transit Network Develop a System that is Financially Feasible Connect major employment/commercial districts, transit centers, institutions, civic destinations, activity centers and transit supportive communities. Operate principally on exclusive right of ways. Provide HCT infrastructure that preserves the environment and supports community goals to develop sustainably. Avoid effects to sensitive environmental areas and cultural facilities. Increase access to jobs, housing, education, and community resource. Links to designated regional centers, urban villages, and economic growth areas. Enhance the ability to move goods and services. Improve connections to other multimodal systems, including both regional and local transit systems. Avoid interlining with Central Link or adding trains to downtown transit tunnel Provide access for transit-dependent populations. Develop cost-effective solutions. Develop a system that is affordable to run. Feasible for the concept to be constructed to HCT standards, (consider topographic, geometric, and other engineering-related constraints of the corridor and within reasonable costs). Minimize potential construction challenges (e.g. avoid substantial regulatory hurdles and/or effects to the natural or built environment). 31

3 5- Evaluation Criteria and Methodologies The evaluation criteria and methodologies were developed based on the project goals and objectives. Tables summarizing the Level 1 and Level 2 evaluation criteria can be found in Chapters 7 and Screening Process The screening process followed three steps, as shown in Figure Initial screening options created a universe of options to connect centers within the corridor. Options were carried forward if they met the project goals and objectives. 2. The Level 1 evaluation created refined corridor alternatives based on the initial screening results. Alternatives were evaluated by performance measures set to meet the goals and objectives. Alternatives that performed well in the performance ratings were carried forward to the Level 2 evaluation. 3. The Level 2 evaluation refined corridor alternatives based on the Level 1 results. More detailed and quantitative performance measures assessed each alternative. Figure 5-1. Initial Screening Process 32

4 6- Initial Screening Information generated from the travel and transit market analysis along with information related to land use, transportation and the environment was used to develop a comprehensive set of options within the study corridors. The universe of options included potential modes and the communities that could be served. Each corridor option was screened against the goals and objectives. During screening, particular weight was given to identifying potential options that did not adhere to the basic definition of HCT, that would be costly to build, or could have major construction challenges. Once screening was complete, the remaining options were combined and modified to create corridor alternatives carried forward to the Level 1 evaluation. See the Initial Options Screening Results Report for more details. 7- Level 1 Alternatives and Evaluation This section describes the development of HCT alternatives within the corridor, the performance measures used to evaluate the alternatives, and the evaluation results. The HCT alternatives were developed and included routes (illustrating segments that would be elevated, at-grade, and tunnel), technology/mode, and potential station area locations. Downtown Seattle alternatives warranted special consideration due to the complexities associated with existing and planned civil structures, infrastructure constraints, and integration with the Ballard to Downtown Transit Expansion Study. Each alternative was then evaluated using the established project goals, objectives, and performance measures including travel market potential, environmental effects, regional growth center linkage, effects on the existing and planned transportation system, economic development, capital costs, and other metrics. A comparative evaluation was then completed for the alternatives and the higher performing alternatives advanced to the Level 2 evaluation. More information about the South King County HCT Corridor Level 1 evaluation process is in the Level 1 Evaluation Memorandum. 7.1 Level 1 Alternatives In order to develop distinct alternatives for Level 1 evaluation, high-level conceptual corridor options were created utilizing the information from the baseline corridor analysis and the initial screening workshop. The concepts focused on accommodating the existing travel and transit demand, which included the following key elements: The largest transit market share is to Downtown Seattle for all the centers in the corridor (except for Downtown Seattle). The travel and transit market in the Downtown-West Seattle-Burien corridor is predominantly oriented in a north-south direction, which aligns well with the proposed HCT alternatives. The travel and transit market in the Burien-Renton Corridor is also generally oriented north-south, which does not directly align with the east-west HCT alternatives. For example, Renton travel is more oriented to Kent and Downtown Seattle. From this information, three high-level concepts were developed to provide a range of options to serve the demand between the urban and regional centers in the corridor, as shown in Figure 7-1. The A concept was developed to provide a continuous connection throughout the corridor. The concept connects Downtown Seattle through West Seattle, to White Center, Burien, SeaTac, Tukwila, and Renton. Service is centered on a single line with a single mode, either light rail transit or bus rapid transit. Concept A closely matches the corridor description listed in the ST2 33

5 plan. The B concept focuses on the strongest existing transit markets between the urban and regional centers and Downtown Seattle. It provides point-to-point HCT service to Downtown Seattle from multiple urban and regional centers with minimal connections provided between the centers. The C concept creates two separate transit lines matched to the strongest travel markets, one from Downtown Seattle to West Seattle and White Center, and a second line from Downtown Seattle to Renton via South Park, Burien, SeaTac, and Tukwila. This concept acknowledges the lower demand present between White Center and Burien and instead directly connects Burien to Downtown Seattle. Variations of these three concepts were developed in order to produce the fourteen (14) alternatives, illustrated in Figure 7-2 and described in Table 7-1. More detailed information regarding the alternatives can be found in the Level 1 Evaluation Memorandum. 34

6 South King County High Capacity Transit Corridor Report Figure 7-1. Primary Concepts Used In The Development Of Alternatives A concept B concept C concept 35