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Introduction
As mobility technology improves and diversifies, there is a growing need for street infrastructure to do so as well. For decades, street space in the United States has catered almost exclusively to vehicular travel. Technological innovations, as well as precedent case studies, present an opportunity to re-think the purpose of the street. In this project, we focus on low-volume local and collector streets, which comprise roughly 70 percent of total street space in US cities. These streets are an ideal starting point to reimagine how streets could serve human-scale users. Our objective as Team Limbo is to improve accessibility, safety, and pleasure for a variety of human-scale modes of mobility.
The central theme guiding our work centers on how vulnerable users of the street--such as pedestrians, cyclists, or those using scooters--are stifled by car-dominant design. Lack of supporting design for these users limits the potential for innovative mobility options, even as the technology for efficient and comfortable micro-mobility vehicles exists. These smaller vehicles pose a very exciting prospect as an emerging bridge between the comfort and convenience of a full-sized vehicle and the social and environmental advantages of biking or walking. As such, interventions that encourage the use and development of micro-mobility are a core aspect of our project.
We acknowledge that there is no one-size-fits-all solution to support micro-mobility users. Our objective is to encourage flexible intervention strategies based on filtered permeability. The idea here is to filter traffic--temporally or spatially-- on the perimeter of targeted areas. This establishes human-scale friendly space on the interior with minimal intervention and also provides the opportunity to experiment with different features and strategies within the perimeter to understand what is most successful for that community. By exploring precedent examples of modal filtration, tactile urbanism, and parallel concepts we will compile a variety of intervention strategies to support our objectives. Finally, we will apply these strategies to an example in Boulder, Colorado.
Background Information and Precedence
Emerging Micro-Mobility Technology
For many years, micro-mobility technology was limited to analog modes, primarily bicycles. Given that more than 60 percent of urban trips are under one mile, expanding micro-mobility capability is an extremely valuable prospect. While bicycles are a dependable, sustainable option, micro-mobility has the potential to expand to a wider range of users with technology and electrification.
Below are some examples of innovative micro-mobility technology. These vehicles have the potential to provide a more comfortable experience that can serve more people and more functions than traditional bicycles. Increased cargo capabilities, protection from the elements, and mechanization are some of the most appealing features these new vehicles offer.
https://logistra.de/news/nfz-fuhrpark-lagerlogistik-intralogistik-hermes-ono-bikes-berlin-rollen-realtest-und-sollen-vans-ersetzen-65157 html https://vancouversun.com/news/who-needs-a-car-electric-unicycles-among-new-forms-of-micro-urban-transportation https://twitter.com/K4RGO/status/372286858182422528 http://cyclelogistics.eu/news/80-market-growth-ecargo-bikes-overtake-electric-cars-germany https://www.freightwaves.com/news/ups-portland-team-up-on-e-bike-delivery-pilot https://www.wsj.com/articles/scooter-startups-take-steps-to-curb-inefficiencies-safety-concerns-11579863600
Electric-powered bikes and scooters, and the sharing services that distribute them, are a promising sign of a new future of micro-mobility in the United States. Still, a lot of innovative potential remains untapped. Vehicles like the Nimbus, a small, three-wheeled personal vehicle, can provide car-like comfort with a fraction of the impact.
These types of vehicles require infrastructure that supports them in order to be successful and to encourage further development. We cannot predict exactly which micro-mobility vehicles will rise to the top of the market. Specific dimensions and features aside, however, for the purposes of our project, we can implicate them by weight and speed.
The graphic below shows how different vehicles vary based on these classifications.
By: Sebastian Bielski & Nelson Girod 2021
2. Filtered Permeability
The concept of filtered permeability in transportation is simple. It may be understood, for our purposes, as a method of reorganizing the hierarchy of street uses to favor pedestrians and micro-mobility users over drivers. By implementing barriers that only allow certain types of users through, we can influence accessibility within the chosen area. Physical examples of these barriers include bollards, planters, or cement blockades. Permeability can also be influenced on a temporal basis, meaning that dynamic physical barriers and/or regulatory signage can allow for types of vehicles sometimes, and restrict them to others. Unfiltered permeability, on the other hand, gives all users the same permeability in an effort to evenly spread motor traffic. Filtered permeability balances the playing field for more vulnerable users on smaller-scale modes, granting them advantages over full-sized vehicles.
Implementing the modal filters necessary to achieve filtered permeability is relatively low impact-- tactile barriers such as planters and concrete blocks can be installed rapidly and at a low cost. As such, they can serve as experimental or demonstrative intervention strategies that may be altered based on their effectiveness.
Filtered permeability is common throughout Europe. London, for example, uses cyclist-only “quietways” to connect bike routes. These junctions restrict vehicular traffic, but cyclists are free to pass through. The image to the right shows how this is achieved through signage, paint, and physical design features. In Copenhagen, the Queen Louise Bridge uses filtered permeability to host up to 48 thousand cyclists daily. It does so by closing off two key sections to all private motorists, which makes the entire route less conducive to car travel. These examples show how the placement of modal filtration is key. Increasing accessibility for micro-mobility does not require totally eliminating cars but rather relies on designating strategic safe space that human-scale users can gain an advantage within the network.
https://ecf.com/news-and-events/news/london-quietways
3. Superblock Cell Model
Perhaps the boldest approach to filtered permeability design is in Barcelona, Spain. Since 2015, Barcelona has adopted superillas, or superblocks, as the core of its mobility plan. The image to the right shows an entrance to one of the first superblocks in the Poblenou neighborhood. The design is anticipated to mitigate pollution and the urban heat island effect while creating safe mobility corridors, as well as space for physical and social activity.
The superblocks are designed like cells, with selectively permeable perimeters that do not allow cars. As the graphic below demonstrates, the perimeter of the superblock is accessible by private vehicle or public transit. The protected interiors are transformed by low-impact design features to function for human-scale users without the need for strict barriers between modes. So far, Barcelona has built six superblocks, each comprising about nine square city blocks, but the city has plans to implement more than 500 of them.
Use of modal filtration in superblock test case in Barcelona. Kevin Brass, 2016
By: Sebastian Bielski & Nelson Girod 2021
The superblock model employs selective permeability to minimize through-traffic of full-sized vehicles, increase flow and connectivity for human-scaled vehicles, alter interior street space for recreation or dining, and create networks that are appealing outside of the car. A basic network intertwined with a local network supports the needs for some cars while prioritizing alternative street uses.
The city is able to implement these superblocks without taking on big, expensive demolition or building projects. This is a significant advantage because not only does it keep costs down, it allows for rapid and flexible implementation. Director of the Urban Ecology Agency of Barcelona, Salvador Rueda, reports that the biggest cost associated with superblocks is signage and rewiring traffic lights; the entire city-wide superblock plan could be implemented for about 53 million USD. He points out that this price tag is less than that of building “a little tunnel”.
Filtered permeability allows us to control the type of traffic circulation within a selected area, essentially increasing the potential for human-scale circulation and decreasing that of full-sized vehicles. Barcelona’s systematic approach to mobility in this context represents a shift in the contemporary understanding of streets. The case in Barcelona, like the examples in London and Copenhagen, supports micro-mobility users by relying on strategic modal filtration rather than rigid modal separation.
4. Tactical Urbanism
Urban infrastructure changes are often resource-intensive, creating many logistical challenges to implementation. Tactical urbanism responds to these challenges by relying on low-impact, versatile design elements. Using tactile design elements to support filtered permeability allows us to build for flexibility (Duhaime 2021).
Tactical urbanism is characterized by creative and strategically placed modular elements. These elements change the hierarchy of the street use with physical components that redesignate street space to accommodate for human-scale users. The example to the right is a project by Better Block, a Dallas-based tactical urbanism organization. The organization collaborates with local agencies to improve human-scale interaction and safety in targeted areas. These images are at an intersection in Akron, Ohio. The community built an installation in what was once a dangerous and unattractive intersection including outdoor seating, seating plazas, food trucks, play areas, a community garden, entertainment, and improved bicycle and pedestrian infrastructure. This project, like many from Better Block, was implemented as a temporary installation. This is an important feature of tactical urbanism; it is often an interim measure. Another way to implement tactical design is through temporary street closures, which take a temporal approach to modal filtration. Bogotá, Columbia’s capital city, exemplifies these strategies in the form of the ciclovia. These temporary street closures are led by local residents who reclaimed the space from cars once a week, on Sundays, in order to get a break from daily congestion and create a space for recreation. On these days, bikes and pedestrians occupy the streets. The idea has spread worldwide as a way for the public to utilize their streets at a human scale taking into account that users’ needs change temporally. Jessica Vargas of the Denver Streets Partnership describes how temporary street closures are a valuable tool to demonstrate street’s potential to the public, and to measure how the public would use streets if they were oriented around people. Temporary measures are a means of starting the process to more permanent changes on our streets.
Better Block project in an intersection in Akron, Ohio.
https://www.betterblock.org/our-work
Challenges and Innovation
Implementing changes to mobility systems is complicated; after all, streets are a public asset, and one of a cities’ organizing principles. Introducing changes around micro-mobility vehicles that might not be widely used, or even exist, yet is a serious challenge. However, this is a promising time for the future of the streets. Street closures brought on by the Covid-19 pandemic have allowed the public to experience some of their local street space in a different way with little development. In addition, the Biden administration recently announced a historic infrastructure plan proposal. This bill, if it passes, will designate an estimated 115 billion dollars to roads and bridges, 85 billion to public transit, and 20 billion to improve road safety. The prospects are exciting but even so, our project faces significant challenges.
Uncertain Modes
The vast majority of discourse and literature on micro-mobility is centered around the bicycle. Our project is inclusive of bicycles, but our purpose is to expand the scope of micro-mobility to include all types of small, lightweight, low-speed modes. These types of modes and their needs are not widely known or acknowledged; furthermore, they are continuing to evolve. Supporting this type of innovation requires flexible design; modal filters might have to move or change over time.
Flexibility and Vulnerability
Another challenge of our project, which is that this design often works best as a demonstrative or experimental intervention. The advantage of tactical design strategies is that they have low barriers to entry; however, this may influence their effectiveness or long-term impact. In the photo to the left, for example, modal filters have been easily installed, but they could just as easily be ignored or removed.
A street in Oakland, California which was closed to through traffic during the pandemic. The modal filters used here, a sign and a cone, are low-impact and highly accessible. While this allows for rapid and inexpensive implementation, it might threaten their effectiveness.
By: Jeff Chiu 2020, East Bay Times
These characteristics, while challenging, are the reason why filtered permeability with tactile elements has so much potential. Many design interventions have the ability to change street space in a dynamic, flexible way. Think gates, chains, moveable planters and barriers, cones, paint, and removable or hydraulic bollards. Electrification can provide even more options for modal filtration technology. Barriers could be sensor activated to allow specific users in; this is a good way to keep local streets open to residents but closed to through traffic. It could also be applied to emergency vehicles and public transit like busses to allow them on some streets as well. Cities could use mobile communication systems to spread information about these projects and to gather feedback. The success of these projects depend on their adaptability; therefore, enlisting community engagement is vital. Even in Barcelona, a leading example, the first superblocks faced resistance because they did not meet community needs. Vicente Guallart, founder of the Institute for Advanced Architecture of Catalonia, says the first superblock test site in Barcelona’s Poblenou neighborhood was not sufficiently adjusted to the unique needs of the neighborhood. Planners need to make adjustments for each neighborhood.
Compiling a neighborhood's needs is a challenge in itself. Discrepancies between local community values and planners often act as a barrier to meaningful community engagement. As Jonathan Freitag explains, people are typically resistant to change in their environments. He argues that the best way to present mobility issues and possible solutions is to show them directly, and joyfully (Freitag 2021). By experimenting with tactile elements, we can incorporate community engagement into intervention strategies through artwork, performance, or educational campaigns. Approaching projects with the intention of them growing or changing with the needs of the community is aligned with public involvement.
The Boulder Application
With Barcelona's Superblock as a canvas for filtered permeability, a variety of tactics are employed to create a hierarchy of spaces to protect the vulnerable users. Designs similar to those rapidly implemented under Covid, like those in Oakland and Portland, have shown how much a small device can do with a light footprint and little upfront cost. Planters of all sizes, that are made elsewhere and dropped into place are especially appealing for their mobile nature. The propper equipment has no trouble rearranging concrete barricades and planters, making them an ideal medium for experimenting with street space. More intensive devices like hydraulic bollards are appealing in the long term as they can more easily flex, perhaps multiple times a day allowing different types of traffic different levels of ease.
Together these designs create a system of systems, a linkage of more protected spaces, for the vulnerable users to safely and enjoyably go about their business. A safer and accommodating network appeals and can be used by people of all ages and abilities, allowing forms of transit other than car to floirush.
Site in central Boulder
Access across the site for all modes is considered, with pedestrain scale modes reciving more direct and safe acess.
Use of scaled filters allows protection for vulnerable users like the existing precedents like those from Portland and Oakland work well in terms of flexibility and functionality.
https://altago.com/separated-bike-lanes/ https://sdotblog.seattle.gov/2020/04/16/announcing-stay-healthy-streets/
https://houstonsystem.wordpress.com/tag/boom-barrier/ https://bikeportland.org/2016/07/18/two-new-traffic-diverters-installed-on-ankeny-and-mississippi-187768 https://bangordailynews.com/2021/02/18/news/portland/portland-wont-barricade-exchange-street-in-2nd-pandemic-summer-heres-the-plan/
Broad Implications
Our project is guided by flexibility; in order for streets to improve, they need to go through a transitory phase. Separating modes by speed, installing filtered permeability components, and drawing inspiration from the superblock cell model are all steps towards streets that are safer and more accessible for human-scaled vehicles. By applying these strategies with an experimental spirit, there is a tradeoff between flexibility and certainty. Team Limbo embraces a level of uncertainty; we are not certain of the technology of the future, nor are we certain of which interventions users will approve of in the long term. However, streets do need permanent change.
Cities in Europe, which have pedestrian death rates far lower than the US average, feature higher density, mixed-use, slower streets in general. This indicates that human-scale safety requires more comprehensive changes from a whole network perspective. The tools that we have researched and employed throughout this project allow us to imagine a different hierarchy of street users in respective examples. The next step is to take a city-scale approach to address human-scale circulation, using the same principles we have presented here. We started on local streets because they are highly visible to local residents, and they are easier to manipulate. They are a natural place to begin to reinvent public street space, but there is a need to expand these networks across cities to popular destinations. After all, the majority of fatalities on the street occur on higher-volume ones. In order to support more versatile travel, the future endeavors of Team Limbo would address routes along larger street classifications.
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