Our Work

Sound Transit’s network expansion is a major step toward efficient, equitable regional access, but physical infrastructure alone doesn’t guarantee improved accessibility. The real value of a transit investment lies in the opportunities it unlocks: jobs, services, and amenities that riders can reach within a reasonable time and cost. Sound Transit is seeking a systematic way to identify the 3 gaps between building transit and delivering accessibility, particularly across different destination categories, including employment, healthcare, retail, education, sports and performance venues, that follow very different spatial patterns, and across neighborhoods with different geographic and sociodemographic characteristics.

Researchers have long studied how well transportation systems connect people to the places they need to go: jobs, schools, healthcare, and more. But most of that research looks only at how long a trip takes, not how much it costs. Few studies have looked at both together, and none have applied that combined lens specifically to Sound Transit’s own service changes.

This project fills that gap. Using detailed data and a before-and-after comparison of Sound Transit’s service improvements, the study will build a clear, evidence-based picture of how transit investments actually change people’s access to opportunities and who benefits most.

Research questions:

• How much do transit improvements increase access to jobs and essential services, and does that benefit vary from neighborhood to neighborhood?
• How does transit help connect workers to major industries?
• How do transit improvements affect where people choose to live, work, and how they commute?
• How does development near transit stations relate to broader patterns of growth and investment across the region?

How the research will get there:

• Review existing methods. The team will study current approaches to measuring transit access and use by employing two established techniques — one that counts how many opportunities (like jobs or services) someone can reach within a set time and budget, and another that also factors in competition for those opportunities.
• Gather and combine data. The project will pull together a wide range of datasets, including job and workforce statistics, Sound Transit’s bus and train schedules (before and after improvements), street and path data, locations of everyday destinations like stores and clinics, housing data, regional travel-time data, and Sound Transit’s own rider survey, creating a detailed, multi-layered view of the region.
• Build a better measurement tool. The team will design a new way to measure transit access that accounts for both travel time and cost, and that treats different types of destinations appropriately, some places (like parks) have room for everyone, while others (like jobs) involve competition for a limited number of spots.
• Compare before and after. By analyzing access levels before and after service changes, the team will show exactly how much transit improvements help people reach jobs, healthcare, retail, and other essential services.
• Share the findings. Results will be documented in a final report, with an optional webinar to walk Sound Transit and other stakeholders through the findings.

Most accessibility studies apply a single measure uniformly across destination types, or study only travel time without accounting for monetary cost. This project’s dual-constraint framework, jointly modeling time and cost, and separately treating rival goods such as jobs and competitive services from nonrival goods such as amenities without capacity limits, captures accessibility effects that existing methods tend to flatten.

Combining that framework with a genuine pre- and post-improvement comparison, rather than a single snapshot, lets Sound Transit see causally what its own investments changed rather than only where accessibility happens to be high today.

This project will deliver:

• Persona-based accessibility profiles showing how different population groups experience the same transit investment differently
• Key findings with fact sheets and a one-page project summary, plus chapter highlights and map appendices, aimed at direct agency use rather than an academic report alone
• Datasets and analysis outputs Sound Transit can reuse for future network expansion evaluation
• An evidence base for prioritizing equitable access to employment and essential services in future service and network decisions, and for weighing trade-offs among cost-cutting scenarios against their effects on specific rider personas

This work is supported by Sound Transit.

Urban Design and Planning, College of Built Environments

Principal Investigator

• Qing Shen, Professor of Urban Design and Planning, College of Built Environments, University of Washington

Graduate Student Researcher

• Hoseok Sa, Ph.D. Candidate in Urban Design and Planning, College of Built Environments, University of Washington