Streets have served as both conduits of movement and as public spaces for human activities and interactions since the dawn of cities. The dimensions, layouts, and design features of streets have, accordingly, always balanced the competing necessities of movement, as dictated by transportation technologies and mode choices of the time, and place making, as dictated by social, economic and cultural aspirations of urban societies (Anderson 1978). These competing forces shaping streets are clearly manifested in the transformations of streets spurred by the widespread adoption of personal automobiles in the 20th century. Transportation technology can produce profound impacts on streets and indeed, entire cities and regions.

At the dawn of the 21st century, urban transportation technologies are in flux again. The personal automobile industry is being transformed by electrification, platform-based vehicle sharing, and driverless technology (Mitchell and Borroni-Bird 2010). Yet, even with these looming tech-based transportation innovations, many cities are continuing efforts to increase their public transport mode share and reduce the presence of automobiles on their streets—whether private or shared (Sadik-Khan and Solomonow, 2017). Public transportation systems are also innovating. Rail and bus services, which have so far been bound to fixed routes and hefty, higher-capacity vehicles, are incorporating custom routes and smaller vehicles to deliver more efficient and less costly solutions for last-mile travel. Bike-sharing systems, updating 19th century mechanical technology with 21st century sharing schemes, are increasingly ubiquitous in cities.

At the same time, urban inhabitants are demonstrating a growing preference for living, working, and relaxing in higher density, mixed use neighborhoods and districts with a wealth of amenities and services that they can walk or bike to (Ehrenhalt 2012). Walkable office space in the US now commands a 70 percent premium over car-oriented, suburban office space (Lynch and Leinberger 2014). Where just a decade ago, streets primarily served to move through auto traffic, an ever-increasing number of cities are undertaking projects that promote active transport and recreational uses of streets and public space. Yet, even as street reconfigurations enhance accessibility for certain modes, groups, and activities, their escalating effects on land values and real estate development activity, particularly in “tight” housing markets, also spur tension and challenges related to neighborhood upscaling and displacement of disadvantaged populations.

Taken together, these advances in mobility technologies, urban lifestyle preferences, and spatial competition are introducing a series of policy and planning questions that cities need to answer before embarking on large-scale infrastructure upgrades on their streets. They call for comprehensive rethinking of how streets should function, who they should serve, and how their spaces should be configured to better balance differing needs and priorities as well as address negative externalities of urban infrastructure investments and spatial restructuring.

Despite the critical role of streets in the future of mobility and accessibility, surprisingly little research has focused on the spatial demands that new transportation technologies pose on streets and by extension, other vehicles, modes, and activities. Questions also remain as to how the design and regulation of public streets might lend towards continued individualized motorization or incentivize the adoption of new mobility technologies in ways that bolster collective, multimodal, and active forms of transport as well as alternative uses of streets and public spaces. Nor is there clear understanding of how evolving street designs and enhancements alter sociospatial access—beyond the immediate area and neighborhood—at urban and regional scales by means of dynamic residential and commercial real estate markets.

The ‘Future of Streets’ research project at the Harvard Graduate School of Design (GSD) aims to address these knowledge gaps by focusing on three sets of critical questions:

1. How could new street-based infrastructure projects for shared, electric, and autonomous vehicles affect accessibility on other modes, particularly walking, biking, and public transit, as well as alternative uses of streets for social, commercial, and cultural activities and interaction?

  • What spatial demands do new mobility systems pose on current practices of street design and regulation? 
  • What tools and frameworks can cities use to measure the impacts of AV infrastructure on pedestrian, bike and public transit mobility as well as broader goals of urban sustainability, sociospatial equity, and public health and safety?
  • How might cities facilitate the adoption of new mobility technologies in ways that bolster collective, multimodal, and active forms of transport? What are enabling factors and conditions?
  • What are possible scenarios for balancing trade-offs between modal accessibility?
  • What aspects of street design and regulation are critical for streets to facilitate social, commercial, and cultural activities and interaction? 

2. What impact could street modifications for new mobility technologies have on land values, residential displacement, and by extension, broader spatial accessibility to urban amenities, services, and resources among different socio-economic groups?

  • Looking to past street reconfiguration projects to promote walking, cycling, and recreational uses of streets and public space, what have been impacts on residential and commercial land values? What have been the socioeconomic and demographic displacement effects on adjacent and surrounding areas and in what time frame? What are mitigating or mediating factors?
  • What frameworks and metrics could be used to evaluate the accessibility trade-offs of past and future street upgrading initiatives among different groups and populations?
  • Given such externalities and trade-offs, how can street-upgrading initiatives best address spatial inequality and uneven access to opportunities in cities and regions?

3. What policy options, planning templates, and political strategies can help cities promote adoption of new street-based mobility solutions that maximize multi-modal, socially inclusive, and environmentally sustainable outcomes?

  • What are policy and planning precedents for best capturing the benefits of improved transportation in ways that enhance public transit and active modes of transport? 
  • How might transportation investments and street interventions be better coordinated with land use planning, affordable housing and commercial development to promote inclusive and equitable access to desired services, amenities, and opportunities? 
  • Who are key decision makers and stakeholders, at what levels of decision making and territorial scales do they operate, and how might their engagements and interaction further transformative streets initiatives that foster multimodal and sociospatial access? 
  • What political strategies have cities used to successfully implement transformative street initiatives and what lessons can be extrapolated from such practices for other cities and communities?

Tackling the above three sets of questions not only requires interdisciplinary thinking but also a combination of multipronged research and critical analysis with forward looking projection and design. The design and engineering aspects of transportation and public space must not only disrupt established modal and road hierarchies but also be juxtaposed with urban economic, housing, and land use development considerations that are inherently bound with accessibility and mobility. Issues and dilemmas of spatial inequality and uneven access to opportunities must be tackled from the start. Not least, the role of political leadership and urban governance should be central to conversations about planning and policy implementation. Reimagining and retooling streets to play a more integrative and inclusive function with respect to mobility and access is not merely a technical problem; it is also a social, economic and political challenge.

To meet this charge, the ‘Future of Streets’ project aims to establish a core research team and interdisciplinary advisory group of transportation technology firms, cities, developers, urban planners, designers, and policy makers to investigate how streets could best balance the emerging needs of transportation, public space, urban form and land use patterns in the 21st century. We believe that Harvard University is uniquely positioned to explore and respond to the abovementioned challenges and opportunities in an interdisciplinary manner that leverages the power of data analytics, innovative design, and strategic planning across issue areas and policy domains. The Graduate School of Design is home to internationally known programs in urban planning and design, landscape and architecture. In addition, we will explore affiliations with other Harvard schools and research centers that have missions pertinent to this research—in particular, the Harvard School of Engineering and Applied Sciences, Harvard Kennedy School of Government, and the Ash Center for Democratic Governance and Innovation.

Project Rationale

Streets fundamentally configure and qualitatively shape the patterns, movements, and experiences of city life. As ubiquitous as they are varying in form and quality, streets are, perhaps, a city’s greatest public asset. They connect different land uses as well as agglomerations of industries, activities, and services. In urban and regional contexts of soaring socioeconomic inequality and political polarization, streets can serve a unique and invaluable function as a shared, public space that brings different others into co-presence and inter-relation. Hence ensuring that streets serve the needs and interests of diverse populations is key to promoting high quality of life, furthering economic development, and fostering democracy.

Yet many cities hesitate to intervene on or improve their streets even when concrete measures are available. For one, uncertainty over which new urban transportation technologies might achieve scale constrains adoption of infrastructure changes. Technological innovation in the mobility sector is especially dynamic and rapidly changing, with some products and practices passing as temporary trends and others taking root as long-term solutions. Additionally, lacking understanding of the spatial and urban requirements of new mobility systems inhibit proactive policy and planning intervention. Despite broadening knowledge that autonomous cars and shared mobility systems place different demands on streets than conventional cars, urban design and planning implications remain poorly articulated and understood.

For political officials and policy makers especially, adopting spatial or configurational changes on streets to welcome new transportation solutions entails considerable risk and trade-offs. For instance, what will be the effects on other modes of transport and mobility such as public transit, cycling, and walking? How will street modifications impact other, place-specific activities that take place in the public realm such as strolling, shopping, dining, gathering, and socializing? Further, transportation infrastructure investments are loaded with externalities, ranging from safety and public health concerns to escalating effects on land values and real estate development activity. Related to potential costs and consequences of street-level changes, the higher visibility of streetscape projects can fuel greater public scrutiny to give another reason for pause.

Such multiple and interrelated challenges require informed and concerted policy and planning responses based on rigorous, multidisciplinary research. The ‘Future of Streets’ project will identify and respond to existing gaps in knowledge with the aim of informing applied interventions that not only generate valuable research findings, but also generate practically relevant and actionable outputs that can be used by practitioners of planning, policy, transportation and engineering as well as related graduate and professional degree programs.