Building transit in the US is substantially more expensive than in other countries with similar planning and institutional contexts. Even though projects elsewhere are often more technically complex, transit agencies in the US usually pay about 50 percent more per mile. For tunneling projects like subways—and especially when New York City is included—the gap can be as high as 250 percent. These high costs help explain why the US has built fewer transit projects in recent decades than its peers.

Encouragingly, these cost disparities are largely not an intrinsic product of local economic conditions such as wages or cost of living. Rather, researchers find that differences in costs across countries are largely driven by variation in national institutions and practices. Fragmented governance, complex environmental review requirements, ineffective procurement practices, and higher litigation risks all contribute to higher costs in the United States. So, too, does another essential but understudied practice that informs most transit investment decisions: community engagement.

In concept, community engagement ensures that infrastructure investments reflect community needs. In reality, these processes often make projects more costly, less effective, and take longer to build. And since engagement is often skewed toward residents with higher incomes, it may produce outcomes that don’t actually reflect community needs.

The United States does not have to choose between meaningful community engagement and building infrastructure efficiently. Indeed, legitimate public participation remains essential, and policymakers can take steps to ensure engagement processes reflect the entire community’s needs without increasing costs or sacrificing effectiveness.

How community engagement can increase costs without improving outcomes

Community engagement processes can drive up the cost of transit projects in several ways.

• Lengthy engagement processes can extend project timelines. Transit projects can take decades to move from concept to operation, with a large share of that time spent in early planning and decisionmaking phases—before construction even begins. For example, the Van Ness Bus Rapid Transit corridor in San Francisco took nearly three decades to be realized, from the initial concept study in 1995 to service launch in 2022. These delays can stem from processes where community input isn’t collected through formal, time-limited channels or when key decisions remain open to revision. Policymakers responsible for major choices—like station placement or route alignment—may hesitate to make a final decision if they receive pushback from constituents, even if that pushback doesn’t represent the majority’s point of view. Because construction costs typically rise as projects are delayed, longer planning timelines can translate directly into higher costs.
• Engagement processes can lead to costly or cost-prohibitive design changes. These changes, such as rerouting lines, tunneling deeper underground, or altering station designs, may address issues raised by potentially affected residents and business owners, but they can also significantly increase project costs without improving performance. In San Jose, California, the Bay Area Rapid Transit Silicon Valley Extension adopted a deep tunneling approach in part to avoid surface disruption. This may have contributed to increased costs: initial estimates put the project at roughly $4.7 billion (about $800 million per mile), compared with actual costs of roughly $12.7 billion (around $2 billion per mile).

Research on public participation also suggests that engagement processes often fail to elicit representative input. Public meetings frequently attract only a narrow group of participants—typically residents who have the time, resources, and political motivation to attend—rather than reflecting the full community affected by transportation projects.

Insufficient engagement also creates challenges

Some infrastructure planners seek to avoid these cost increases and delays by forgoing legitimate public input. They instead follow a “decide, announce, defend” approach, where government agencies make major decisions internally and present them to the public only after major choices have been made. This approach can undermine trust, provoke community opposition, and in some cases, lead to project delays or cancellation.

In Phoenix, a lackluster outreach effort, according to residents, in the lead up to the construction of the South Central Light Rail project resulted in the city council nearly halting the project altogether. Instead, the council directed the city’s transit authority to alter the design.

These experiences show that engagement and efficiency are not mutually exclusive. Transit planners can be intentional in designing engagement processes that support inclusive participation and timely project delivery.

How can US projects implement effective community engagement?

More cost-efficient countries appear to use engagement processes that are structured and time bound. Based on insights from previous research and early findings from our literature review for related work, we have identified several approaches that transit planning stakeholders can use to improve engagement while avoiding unnecessary delays:

• Focus engagement earlier in the planning process. Early engagement can help shape major project decisions, such as the location of new stations, but technical design choices later in the process should not remain open to repeated renegotiation. It is important to gather public input on project details, but project managers should be empowered to make decisions without subjecting every detail to lengthy community consultation, especially when key choices have already been made.
• Ensure engagement is representative of affected communities. Agencies should use demographic data to identify who lives in and travels through project corridors, then track participation to ensure engagement reflects these populations’ needs.
• Show how project planners learned from community engagement. Agencies should document the major concerns they hear from participation processes and show how they’re addressed in project decisions. They should clearly articulate trade-offs, showing how changes to project designs could affect project outcomes.
• Increase transparency around project costs. Public cost benchmarks, such as those used in countries like Italy and Turkey, can help communities understand trade-offs between design choices and project costs. This is especially important when the agency designing the project is responsible for paying most of its costs. Changes that increase the cost of one project may make it more challenging to afford other projects the community wishes to build.
• Strengthen in-house technical expertise. Agencies that develop more project design capacity internally, rather than relying on external consultants, may be better positioned to make informed decisions and reduce costly design changes because of engagement challenges.
• Limit cost escalation from design revisions. Create contingency budget limits so engagement does not lead to cost escalation above a specific amount. Jurisdictions with lower-cost transit projects have managed to deliver more complexity by implementing lower contingency budgets. Italy and Turkey have also adopted policies that prescribe percentage maximums on contingency budgets.
• Reduce the number of people involved in routine approvals. Limiting the number of individual actors needed to make routine decisions can help agencies respond to the needs of communities quickly and efficiently.

Community engagement can, and should, be representative and efficient

More research is needed to identify engagement models that balance democratic accountability, representative participation, and efficient project delivery. Some early evidence (PDF) suggests that newer forms of engagement—such as digital outreach—may not fully resolve long-standing participation gaps.

Our research team is examining community engagement structures across various US cities and around the world to better understand how engagement models interact with governance structures, project timelines, and design decisions. These questions are increasingly relevant beyond transportation. Similar tensions between public participation and timely infrastructure delivery have emerged in housing development, energy infrastructure, and climate adaptation projects.

As cities and regions work to build more infrastructure, understanding how to design effective and efficient engagement systems will become increasingly vital to meeting community needs.