4. Transformational change #2: from sprawl to proximity

Like traffic volumes, decisions on where to live are endogenous to the system. As investments in roads increase their capacity (B1 in Figure 4.1), the radius accessible within a certain time budget by car (e.g. 30 minutes) increases.

This new car-dependent “proximity” to city centres, coupled with lower housing prices in peripheries (and other advantages that less dense areas may have compared to city centres), incentivises people to move to the suburbs. To take an example, Resnik (2010[1]) describes the way in which urban sprawl in the United States has increased since the 1950s, as individuals moved out of urban centres to evade noise, crime and traffic. The draw of larger homes and more space – at least partially fuelled by the widely disseminated American Dream narrative – accelerated this flight to the suburbs, where zoning regulations created single-use developments (Resnik, 2010[1]) (see below for more on why this type of development was prioritised). This resulted in large, low-density residential areas interconnected by roads, where residents typically commuted by vehicle (Resnik, 2010[1]).

In the preceding paragraph, the word proximity is in quotation marks as road expansion, rather than creating “real” proximity, compensates for the lack of proximity (or “fake” proximity) with more mobility. Furthermore, once people move to car-dependent areas, they may have incentives to move even further away, further reducing proximity and increasing the need for more mobility, bringing us back to the dynamic of induced demand (B1, B2 and B3). Moving further away may allow people to benefit from lower housing prices with a similar time budget to the city centre (e.g. five or ten additional minutes by car), without losing much in terms of alternative transport modes, as they already did not have many options other than the car. While in theory public transport could expand to remote places (benefiting from new roads), the rapid and scattered expansion of development limits the extent to which public transport networks can keep up, since a minimum density of demand is important for public transport to be viable and attractive (see below1).

As more people move to the suburbs and become car dependent, congestion starts to appear, increasing the average travel time for trips from the suburbs to the city centre, thus potentially slowing or balancing the urban sprawl dynamic (B4 in Figure 4.2). Housing prices in the periphery (not shown in Figure 4.1) also start to increase as demand increases, further reducing immigration and the development of those suburbs (Sterman, 2000[2]).

What can be observed is, however, that suburban development tends to continue. This can be the result, at least in part, of the now car-dependent population’s pressure for authorities to build more roads to reduce congestion and time travel, bringing us back to the induced demand dynamic (B1, B2 and B3). As housing prices increase, there is also an incentive for the construction industry to build in the new suburbs further away from cities. Building away from cities is a way for the construction industry to accelerate market expansion, since space is limited in places that are already developed and construction permitting may be slow due to the higher density of affected neighbours and greater complexity of the infrastructure.

While suburban development is not always an issue in itself, the way this expansion has taken place is a barrier to sustainable transport systems. The expansion of suburbs has followed a single-use or siloed logic, in which each area focuses on a specific use: suburbs tend to be residential neighbourhoods, places of interest are often concentrated in city centres or in other specific areas (e.g. shopping malls), and offices are clustered in working districts. The resulting development pattern is low density and often scattered. This leads to clusters of badly connected, most often only by roads, built-up areas, and increases the need to travel long distances (Figure 4.3). The fact that suburban expansion is privileged over infill development2 (to a great extent due to the reasons outlined above) is also problematic, as it contributes to the conversion of green areas.

Decades of policies focused on mobility, “blind” to the importance of creating proximity and delivering accessibility (see more in Chapter 2), are part of the reason why suburban development has followed this single-use logic. When the objective is to increase mobility and speed up travel, then expanding the size of the built-up area to areas with cheaper prices may not seem directly problematic – as long as more roads are built to connect the different areas and accommodate the increased traffic volume. The externalities of such expansion, if recognised at all, are also accepted as “necessary and inevitable costs”. Greenhouse gas emissions, air pollution, habitat and biodiversity loss, overconsumption and resource waste are some of these costs (McDonald et al., 2019[3]; Mahendra and Seto, 2019[4]). Dependence on cars is not seen as problematic either, as long as road capacity expansion “reacts” (or “predicts” and “provides”) to maintain the average speed of travel within an acceptable range. The privilege given to emission- and space-intensive modes of transportation like private cars is also not seen as an issue through a mobility lens, as the fact that using so much space to accommodate cars leaves less space for other modes and urban functions (green space, centrally located housing, etc.) is also ignored. Note that considering certain impacts as “externalities” or “side effects” reflects that a greater importance is given to certain outcomes relative to others. As explained by Sterman, Forrester and Standish (2002[5]), “There are no side effects – only effects. Those we thought of in advance, the ones we like, we call the main, or intended, effects, and take credit for them. The ones we did not anticipate, the ones that came around and bit us in the rear – those are the ‘side effects’”.

Narratives supporting car-dependent lifestyles have also played a significant role in increasing the attractiveness of suburbs. Communication efforts to associate the car (and the detached houses described above) with notions such as freedom, rights or status (Norton, 2011[6]; Gössling, 2020[7]), also contributed to normalising car dependency and associating it to increased well-being (Freund and Martin, 1993[8]) (see Figure 4.3).

The logic of single-use development described above significantly constrains the scope for climate action. In single-use or siloed urban areas, people need to travel, often long distances, for almost every need: to work, to the bakery, to the cinema, to school or to the park. Longer distances imply that active modes of transport are less and less of an option. The attractiveness of public transport is also negatively affected, both further increasing car dependency.

With a scattered population that needs to travel long distances and depend on cars to meet its daily needs, climate policies such as carbon prices also become politically unfeasible. In car-dependent, single-use urban systems, the behavioural shift that is intended by the introduction of carbon pricing is simply not possible (or its scope is very narrow) due to the limited or lack of alternatives to car use. Carbon taxes at the rate needed to meet ambitious emissions reduction targets are unlikely to be accepted by the population, potentially leading to social upheavals such as the Yellow Vests (Gilets Jaunes) movement in France. If not accepted by the population, the implementation of such policies will be unlikely or will be rolled in and out periodically, thus ineffective. Chapter 6 further develops this topic.

Scattered and single-use development, and the resulting car-dependent systems, can also greatly affect well-being more broadly. For example, children’s freedom is affected as they become dependent on their parents to get to places until they can drive a car. Parents’ time availability (to do other things than take children places) is also greatly affected by this trend.

The next section discusses what it would entail to reverse the dynamic of urban sprawl in terms of the types of policies, measurement frameworks and governance mechanisms.

Chapter 3 identified the need to shift from a “predict and provide” mind-set, which is narrowly focused on providing roads to allow for car travel, towards holistic approaches to design and manage public space. How to manage and design public space is at the core of Complete Streets and Place-making approaches, and Chapter 3presented examples of how these approaches could be implemented to transform and better manage streets (including by reallocating space, improving parking policy and using road pricing). It must be emphasised that this is a first step towards reversing car dependency by reversing induced demand.

This section goes beyond the design and management of public space and focuses on changes needed to rethink territories as a whole (beyond public space) to contain and reverse urban sprawl. A number of specific policies and actions (e.g. zoning regulations, housing policy, etc.) are crucial for the redesign of territories. A detailed analysis of these policies is beyond the scope of this report. This analysis focuses rather on the necessary changes in governance, planning and regulatory frameworks guiding spatial planning (including those policies mentioned). The focus is on how these changes can help shift policy away from “proximity blindness” (see Chapter 2), by linking transport and land-use decisions, and make the sustainable delivery of accessibility central to decision making.

While the policies in Chapter 3 (e.g. Superblocks) can be implemented, and lead to positive impacts in the short term, the changes presented in this section are deeper, longer term changes. They are, however, necessary for the transition towards sustainable-by-design systems. Importantly, longer-term changes do not necessarily mean several decades. For instance, according to Savills (2016[9]), implementing the type of large-scale renewal projects proposed for London, which build on Complete Streets (see below), would take around ten years to be fully implemented. In addition, as shown by the example of Pontevedra described below, a number of benefits (e.g. reduced traffic and pollution, road safety improvements) are progressively unlocked as territories transform.

A number of synergies between the actions in Chapter 3 and the objective of redesigning territories addressed in this chapter can be made. For instance, redesigning streets can liberate space not only for other public use, but also for other uses (e.g. new or expanded areas for local businesses). In the mid- and longer run, liberated space can be used even for new development (e.g. bringing housing to more centrally located areas). Similarly, revisiting parking policy can help avoid future sprawl and rather foster compact development, in addition to its shorter term impact on modal shift (Franco, 2020[10]).

Moreover, new development and urban renewal strategies can build on and benefit from Complete Streets and Place-making approaches to rethink spatial development more generally (i.e. beyond public space). Place-making refers to “the production of liveable and sustainable places… [and thus it] …should be included in the missions of the various disciplines that address the organization and management of the built environment” (Palermo, 2014[11]) . Thinking of territories in terms of Complete Streets and Place-making can allow planning for development (or redevelopment) innovatively. For instance, it can allow planning with a different balance between space used for mobility and space used for other urban functions, and shed light on the importance of infrastructure connectivity to increase territories’ attractiveness (Palermo, 2014[11]).

A study in London sheds light on the potential of applying these concepts to city renovation projects (Savills, 2016[9]). The study focuses on the redesign of an area dedicated to social housing (1750 housing) that could, via a Complete Street-based redesign, provide additional and better quality3 housing (Figure 4.4). The redesign project aims to “increase the supply of housing in popular, high quality, mixed-use and street-based neighbourhoods, which reflect the urban form of London’s best-loved places” (Savills, 2016[9]). Cost-wise, the report estimates that urban renovation using the Complete Streets urban layout would be less costly per hectare of renovated land (GBP 19.9 million) compared to what the report refers to as “contemporary renovation” (i.e. a business-as-usual approach) (GBP 21.8 million). The value of real estate would, instead, be higher in the former: total end-value per hectare was estimated at GBP 48.1 million for renovation under a Complete Streets approach, against GBP 40 million for contemporary renovation (Savills, 2016[9]).

A design based on Complete Streets would allow the provision of between 54 000 and 360 000 additional housing units. The author explains the estimation of this range as follows: “the bottom of the range is based on an assumption that density is increased from 78 homes per hectare to the bottom end of the range achieved on the six example estates (109 homes per hectare). The top end of the range assumes that the density is increased from 78 homes per hectare to the top end of the range achieved on the six examples (279 homes per hectare)” (Savills, 2016[9]).

Urban redesign based on Complete Streets and place-making approaches is often associated to large urban areas, and seen as irrelevant for smaller cities or towns. Pontevedra, a city of 83 000 inhabitants in Spain (Galicia region), demystifies such a belief and provides a concrete example of how these ideas can be applied beyond large metropoles (Figure 4.5).

Pontevedra undertook a number of initiatives in line with Complete Street and Place-making approaches, with the aim of reversing sprawl by increasing the attractiveness of the central areas of the city. A Pontevedrian public official explains that “to encourage people to return to live in the city, it was necessary to improve the quality of life, reduce traffic, and create a human city. By acting quickly, we have stopped urban sprawl” (Burgen, 2018[12]). Moreover, in line with one of the key messages in this report, the transformation of Pontevedra was carried out with the logic that the solution to urban mobility is beyond mobility; thus, instead of the city being conditioned by the need to improve mobility, mobility should be conditioned by the need to improve the city (IEEE, 2020[13]).

In terms of street redesign and management, the basis was laid down by recognising public space as a universal right (IEEE, 2020[13]). Measures implemented included the banning of road traffic and the pedestrianisation of the central area of the city, which progressively extended to other areas (in total 6.7 km2) (Jiao, He and Zeng, 2019[14]) ; limiting speeds to 20-30 km/h; and the doubling of pedestrian space, where benches, green spaces and playgrounds were installed. In fact, the general rule has been to allocate to pedestrians half of the space in streets that are more than 2.5 m wide, and all of the space in streets that are less than 2.5 m wide (IEEE, 2020[13]). Since car drivers looking for parking spots were identified as one of the main sources of congestion, parking spots were limited to 15-30 minutes, and on-street parking was eliminated and partly replaced by underground and periphery parking. For the new parking regulation to be enforced, the number of police officials was increased, and parking fines of up to EUR 200 are given for not respecting the parking rules.

Pontevedra’s changes go beyond street redesign. The changes are a concrete example of a mental shift from a single-use logic towards mixed land-use planning. A landmark policy in this regard has been the withholding of planning permits to shopping centres in the periphery in benefit of local businesses, with the aim of incentivising local economic activity, creating jobs, and increasing the attractiveness of walking and cycling as well as social interactions.

The city also undertook communication and educational campaigns. A metro-like map, called the Metrominuto, shows the services and shops available by foot (Figure 4.6). The local government Pasominuto programme provides 20 walking itineraries with information such as calories burnt to promote walking. A map with bike paths within a 20-kilometre radius around the city is currently under development (Burgen, 2018[12]).

The benefits of Pontevedra’s strategy are numerous. Overall, the central area of the city has become more attractive, and has welcomed 12 000 new inhabitants (Burgen, 2018[12]).

The results achieved in Pontevedra are an example of the notion of “disappearing traffic” discussed in Chapter 3: there is 69% less traffic in the city centre and 90% less in the downtown core compared to 2013, meaning that 7 (or 9) out of 10 cars have “disappeared”. Thanks to the creation of proximity, the majority of people’s trips are made by active or shared transport (70% by foot, 22% by vehicle, 6% by bike and 3% by public transportation) (Burgen, 2018[12]), positioning Pontevedra on the right-hand side of Figure 2.1. Pollution and CO2 emissions decreased by 61% and 70%, respectively, over the same period. The improvements in terms of road safety were also impressive. Where 30 people died due to traffic accidents from 1996 to 2006, on the same street, only 3 died over the next 10-year period, and there have not been any traffic fatalities since 2009 (Burgen, 2018[12]).

The example of Pontevedra highlights that approaches that aim to restore a balance between mobility and proximity are relevant and can be applied in small cities. The example also sheds light on the multiple synergies created through the initiatives described above. In terms of trade-offs, one main drawback of Pontevedra’s strategy has been a certain increase in traffic in the peripheries. Such a drawback can be linked to the fact that the initiatives were mainly carried out at the city centre level, and do not reach peripheral areas (as discussed in Section 4.2.1).

Importantly, the Complete Streets and place-making approaches can also be applied in suburbs. In Canadian suburbs and cities, malls are being transformed into mixed-use developments (CBC, 2019[15]). For example, the parking lots of the Square One Shopping Centre in Toronto’s suburb of Mississauga will be converted into 37 towers including residential space, retail, offices and green spaces. The goal of the project is to create a transit mobility hub and connect the space to the Hurontario LRT (a light-rail line currently under construction) (CBC, 2019[15]).

In the case of rural areas, which can in many cases be part of the larger commuting zone of a city, a Complete Street and place-making logic can also help to create commercial corridors and revitalise economies that have suffered from scattered and single-use development (which have also made these territories highly dependent on cars). As discussed by the US EPA (2012[16]), rural regions can plan and encourage the development of their commercial base. This can help strengthen the town centre and solidify revenue sources for communities to support their schools, roads and emergency services. Using mixed zoning to incorporate commercial and residential buildings reduces driving distances and increases the use of active transportation for residents’ daily travel. Converting warehouses or light-industrial buildings to mixed-use developments, for instance, can revitalise an area. Commercial growth along corridors can reduce scattered development, create a sense of community, increase the tax base for the municipality and active travel, and create jobs (US EPA, 2012[16]).

The rest of this section discusses changes in governance, planning and regulatory frameworks that are necessary for redesigning territories. Section 4.2.1 discusses the case of metropolitan transport authorities (MTAs), an institutional set-up that has proven instrumental for transitioning urban territories (including cities and their larger commuting regions) towards more sustainable transport and urban systems. Section 4.2.2 introduces frameworks and indicators that can help authorities systematically guide development according to accessibility criteria and which are consistent with the Complete Streets and Place-making notions. Finally, Section 4.2.3 illustrates the important role that new development regulations can play in redesigning territories. The section presents two regulations currently misaligned with the transition towards car-independent territories – minimum parking requirements and traffic-oriented transport assessments – and provides recommendations to correct them.

Authorities in charge of transport, land-use, urban planning and housing are key actors in the transition towards more sustainable transport and urban systems. Redesigning territories is particularly challenging, as it implies integrating decisions from all these actors (among others) and focusing on the whole of territories, which seldom coincide with administrative boundaries and include areas with distinct characteristics and needs. Evidence suggests that focusing only on inner cities (often a small share of current built-up city areas and their commuting zones) has contributed to increasing accessibility gaps and pricing differentials in housing costs between these inner areas and more peripheral ones, potentially accelerating sprawl (Siripanich, 2019[17]).

In the process of decentralisation, relevant powers over transport and urban spatial authorities have often been granted to the local level of government. This has led to more informed local decisions, but also to fragmentation and a multiplicity of not-necessarily co-ordinated or aligned plans and strategies for territories that are part of a same metropolitan area or Functional Urban Area (FUA) (see Box 4.1)

MTAs are an institutional set-up with the potential to strike a balance between decision making that is decentralised enough to reflect actual local needs, and co-ordination, as centralised enough as to ensure coherence at the metropolitan area and/or FUA level (ITF, 2018[18]).

MTAs have proven to be successful in managing the needs of wider city areas and in many cases their commuting zones as well (depending on how they are set-up) (ITF, 2018[18]). This allows better connecting and integrating different areas (e.g. inner cities and suburbs or rural areas that are part of larger commuting zones). They have also played a key role in fostering the co-ordination of transport and spatial planning, in particular when the institutional set-up is such that MTAs coexist within metropolitan bodies that also plan at this level for land use. Such co-ordination is central to striking a balance between mobility and proximity, which is in turn fundamental for the delivery of more equitable and sustainable accessibility.

The ITF (2018[18]) highlights best practices based on in-depth analysis of the Paris, London and Barcelona MTAs. The authors associate the following characteristics to functional MTAs (further discussed below):

  • formal authority with legal backing over a specified territory, with clearly defined responsibilities

  • authority over strategic-level planning

  • regulatory capacity

  • competence over wide multimodal transport modes, i.e. competence including roads, and planning for active modes, rather than only public transport

  • predominant role of subnational authorities in the decision-making process (e.g. through a predominant role on the governing board or similar body)

  • dedicated funding and decision-making authority over the use of the transport budget

  • dedicated and highly skilled staff.

The MTAs analysed have legal backing for their competence over transport planning at different territorial scales. For example, the Paris area’s MTA (Ile-de-France Mobilités) covers the entire region of Île-de-France, which is a territory that coincides well with the metropolitan region or functional urban area linked to Paris, as defined by the EU-OECD methodology presented in Box 4.1 (ITF, 2018[18]). Transport for London (TfL), on the other hand, covers the Greater London area, which coincides with the city or metropolitan area; i.e. a much larger area than London’s inner city (which was the original city), but smaller than the entire functional urban area or metropolitan region. In Barcelona, two MTAs coexist and co-ordinate with each other: the Autoritat del Transport Metropolità (ATM) is in charge of transport infrastructure across the metropolitan region (i.e. including the city and its commuting zone), while Àrea Metropolitana de Barcelona (AMB) covers Barcelona and its 32 adjacent municipalities (metropolitan area or city). Barcelona’s case is a particularly interesting institutional set-up: AMB covers the continuous built-up area and can thus plan the network of local buses, bicycle lanes and pedestrian facilities in a way that makes sense for the entire area. ATM covers the city plus the larger commuting zone (i.e. the metropolitan region) and plans for the commuting trains and regional buses. Both institutions co-operate and co-ordinate so that planning and investment between the two scales is coherent (ITF, 2018[18]). In the case of the Paris region, the City of Paris (City of Paris, n.d.[20]) has embraced the 15-minute city framework (see next section), which can importantly facilitate planning development (and redevelopment) along Complete Streets and Place-making principles. An important challenge will be to find ways to include other territories in the larger city area and the commuting zone. The fact that no authority holds power over transport planning at the level of the wider city (i.e. Paris and its near periphery), can hinder or make such integration difficult.

Authority over strategic-level planning (i.e. the development of a vision with which infrastructure and policy need to be consistent as well as the long-term plans to implement it), is also identified as a key characteristic of successful MTAs. Importantly, such planning is facilitated by MTAs being embedded in larger metropolitan bodies with land-use planning competencies. For example, TfL is embedded within the Greater London Authority4 and AMB in Barcelona not only has power for transport, but also over land use and environment. Overall, it is important that the strategic plans for transport policy and infrastructure developed by the MTAs are co-ordinated and consistent with urban plans. For example, Ile-de-France Mobilités is in charge of the Mobility Master Plan for the region (PDUIF), which directly influences the Local Urban Master Plan (PLU). TfL develops the Mayor’s Transport Strategy for the Greater London Area in coordination with the London Plan (the spatial plan for London). In the case of Barcelona, ATM develops the Mobility Master Plan for the metropolitan region (PDM), while AMB develops the Urban Mobility Plan for the metropolitan area (PMMU), which is closely linked to the Metropolitan Urban Master Plan (ITF, 2018[18]). In all cases, such strategies are embedded in important processes of public participation and consultation, in addition to the participation of the various local governments. These planning documents are also embedded in multi-level planning frameworks, guiding plans for lower government levels (e.g. boroughs or municipalities) and ensuring consistency with national goals and planning (ITF, 2018[18]). Showing consistency of projects with such plans is also a requisite for eligibility for several national funds dedicated to mobility and urban infrastructure (ITF, 2018[18]).

Having regulatory capacity over transport services is also a key condition for MTAs to be able to make the vision and long-term strategy described above operational. For example, MTAs operating in fully deregulated transport settings may develop ambitious long-term strategies, but without the capacity to set standards for services or plan for routes, their capacity to implement the strategies will be very limited (see Chapter 5). Regulatory capacity has been key for TfL and AMB to improve bus concessions and regulate service through public tendering, for instance.

Implementing comprehensive strategies (including Complete Streets and Place-making approaches) also requires MTAs to have competence over multiple transport modes and policy levers, i.e. beyond public transport to include road use and allocation, as well as the capacity to plan for active modes. TfL has improved public transport, walking, and cycling conditions through a combination of actions, such as improving tendering processes to incentivise better bus services by private providers, road reallocation in favour of public and active modes, the development and improvement of active and public transport infrastructure, and congestion charging. Part of TfL’s ability in doing so is its regulatory capacity over different modes (including taxis and private-hire services), as well as competence over road safety and a major influence on road management and design.

The predominant role of subnational authorities in the decision-making body (e.g. board of directors, council, etc.) is also fundamental to ensure a shared vision for the area. In addition, this is a crucial condition for making the establishment of such entities possible in places where decentralisation has already occurred. Because transferring some of the capacity already granted to local entities (e.g. municipalities, boroughs, etc.) needs to be transferred to the MTA, it is normal that such entities will only come on board if their effective representation in the decision-making process is ensured.

Dedicated funding and decision-making authority over the use of the transport budget is key for MTAs to create well-integrated and competitive transport networks. As discussed in Chapter 5, setting up an MTA can also serve to put in place financial frameworks that can help enlarge the sources of funding of transport networks, reducing pressure over transport budgets.

Finally, dedicated and highly skilled staff is another crucial characteristic of fully functional MTAs. Staff with data analysis skills, for example, can allow MTAs to gather data to inform decisions, and better respond to users’ needs while shifting metropolitan areas and regions away from car dependency. MTAs with data-skilled staff (and the funding to ensure those positions) can also establish partnerships with on-demand service providers and other institutions (e.g. universities) for the development of innovative platforms and information services that better foster the integration of private and public services in the pursuit of better alternatives to car use.

Better spatial planning (including, but beyond, public space) and design are at the core of finding a balance between mobility and proximity, thus increasing the attractiveness of active and shared modes, and ensuring equitable, quality and sustainable accessibility. This section presents planning frameworks and metrics that can support the enhancement of spatial planning, with the potential to guide decisions towards achieving these goals and in this way become central to reducing transport-related emissions.

The “15-minute city” framework is a good example of a framework that can play a key role in guiding, and co-ordinating, planning decisions towards rebalancing mobility and proximity, leading to “healthier” territories. In 15-minute cities, urban development is centred on accessibility, so that people can get to (many) places by walking and cycling in less than 15 minutes. As such, planning is systematically guided towards creating proximity (especially to basic services and opportunities that people need the most frequently). At the same time, it creates the conditions so that connections by walking and cycling between people and those services can ensure that these modes are the most convenient. While the 15-minute city builds on the notion of denser cities, it looks beyond the creation of density, integrating the notions of mixed land uses and diversity of opportunities as well. Because the priority in planning is given to accessibility by sustainable modes, and on people having access to the places they need and like, the framework is useful for integrating Complete Streets and Place-making notions to urban development and planning.

Planning in this framework focuses on looking at a scale often neglected: a territory larger than the neighbourhood but smaller than the metropolitan region (Duany and Steuteville, 2021[21]). Nonetheless, the model allows rethinking the entire urban area or region. The idea is that, rather than having inner cities surrounded by car-dependent suburbs and towns, territories could be redesigned as networks of 15-minute cities (and smaller towns), reversing urban sprawl and unlocking enormous opportunities for emissions reductions and better daily lives. Importantly, this can be used to redesign large metropolitan areas, but can also be implemented in small cities (as the case of Pontevedra illustrates) and rural towns.

The framework defines three radii accessible by foot and bike within which authorities need to ensure proximity to a certain number of services (Duany and Steuteville, 2021[21]):

  • A first five-minute walk (around 0.4 km) radius where people have access to ordinary daily needs: small businesses, and a central square or a main street with a minimum level of mixed land uses. An indicative population within this radius is around 2 600 people.

  • A second radius determined by a 15-minute walk (around 1.2 km) contains a full mix of services, i.e. grocery store, pharmacy, general consumption places and public schools. It also contains larger parks (serving multiple neighbourhoods) as well as larger employers (compared to the small businesses above). An indicative population within this radius is about 23 000 people.

  • A third radius determined by a 15-minute cycle (around 3 km) contains major cultural, medical and education (e.g. higher education) centres. This radius also allows access to regional parks and regional transit stations. This would include a population of around 350 000.

By encouraging planning that consciously brings people, opportunities and places of interest closer together, the 15-minute city framework can lead to “healthy” territories (right panel in Figure 2.1) in which the bulk of trips are made by foot, bike, micro- or shared mobility modes that excel in short distances. Not being space-intensive, these transport modes reduce the space needed for mobility purposes, further allowing the creation of proximity (creating a virtuous cycle). This does not mean that people will not go further than these radii, but the idea is that they do not need to for most needs. Micro-mobility (including electric bicycles) and public transport should be encouraged as the most competitive alternative beyond the 15-minute radii, leaving car use for very specific trip purposes. For instance, an electric bicycle can allow a much larger perimeter than a normal bike in a 15-minute period (Duany and Steuteville, 2021[21]). In addition, public transport and micro-mobility can also provide an alternative for occasions where walking and cycling are not adequate (e.g. when people are in a hurry), in this way helping to avoid car use. For instance, an electric bicycle can allow reaching a perimeter of around 2.6 km (i.e. between the second and third radii) in five minutes (Duany and Steuteville, 2021[21]).

Accessibility metrics can also be incorporated into specific planning tools to ensure that new development and urban renewal fosters increased proximity between people and places and that better connections through sustainable modes are prioritised. The Public Transport Accessibility Level indicator (PTAL) used by TfL in London, and the Housing plus Transport (H+T) Affordability Index used in the United States are two examples (discussed below) of indicators that have in the past been effectively linked to decision making for guiding spatial planning and development. The radii described in the 15-minute framework could also be used as an important reference for setting minimum accessibility levels by walking and cycling and to different types of opportunities and services as standards to guide new development and urban renewal.

TfL uses the PTAL indicator (among others) as a standard for linking urban development location to public transport accessibility, and PTAL is an important element in the London Plan (London’s spatial plan). It also uses the PTAL to guide the permitted density of development and for linking maximum parking requirements for new development (see below) to public transport availability (ITF, 2019[22]). TfL introduced WebCAT,5 an open web portal for connectivity assessment, in order to make its data and analysis available to boroughs, developers, planners and other key stakeholders. As part of this, an interactive mapping tool provides users with PTAL values in any location across London. Users can also see PTAL levels that would result from different scenarios (e.g. the development of a certain infrastructure) and create their own PTAL maps (ITF, 2019[22]).

WebCAT has importantly contributed to making regulation linked to PTAL (e.g. planning obligations, land-value capture mechanisms) transparent for developers and raising acceptability. While more sophisticated indicators have been developed by TfL over time, PTAL remains an important tool for policy design and communication with different stakeholders (e.g. developers) due to its simplicity, transparency and broad use. PTAL has also served as a basis for identifying and redeveloping “opportunity areas” in London. Opportunity areas are large areas of brownfield land that either have good public transport access or where, due to its characteristics (e.g. location), good public transport connections could be easily developed (ITF, 2019[22]). Linking redevelopment strategies for these areas to analysis and criteria based on the analysis of PTAL helps ensure that their redevelopment contributes to environmental, social and economic goals.

The Housing plus Transport (H+T) Affordability Index6 is another example of an indicator that has helped to integrate transport and land-use decisions more systematically. In a number of US states (e.g. Illinois and El Paso, Texas), the index allowed prioritising funding7 for subsidised housing for the most location-efficient projects (i.e. the selection process prioritised projects located near public transport or with good access to job centres) (ITF, 2017[23]). As a result, the funds supported the development of affordable housing close to public transport, which helps align climate and equity goals (CNT, 2018[24]).

Similar indicators have been developed to help prospective homeowners factor in both housing and transport costs while exploring household choices. In the San Francisco Bay Area, the H+T Affordability Index was adapted to help prospective homeowners understand the overall financial impact of living closer to, or farther from, work (ITF, 2017[23]). Similarly, the coût résidentiel developed in France combines the cost of housing and transport to inform public policy and household choice (Mattioli, 2015[25]). The coût résidentiel is a publicly available indicator consisting of the breakdown of all household expenses due to residential location, including travel and accommodation (Cerema, 2020[26]).

Both parking regulations and transport assessments for new developments, such as residential buildings and offices, importantly impact urban form. In most countries, law for new building developments requires a minimum number of parking slots. Such minimum parking regulations incentivise car use (Ajuntament de Barcelona, 2014[27]) and increase housing costs (Litman, 2016[28]), by requiring space – that could be used for other uses (e.g. more housing units, green or recreational spaces) – to be allocated to car parking (Brueckner and Franco, 2018[29]). This can make it financially unviable to develop more affordable housing units and often consumes valuable land near public transport; it also implies cross-subsidisation from non-car to car users.

Shifting away from minimum requirements is a key step for supporting sustainable and equitable developments. London, San Francisco, Seattle and Mexico City changed their parking policy from minimum requirements to maximum requirements (Franco, 2020[10]). London, for example, managed to halve the number of parking spaces in new residential buildings with such a reform (Guo and Ren, 2013[30]). In San Francisco, downtown parking is limited to 7% of the building’s floor area, while in Seattle the maximum allowed in office space downtown is one parking space/1 000 ft². In Mexico City, minimum parking requirements were abolished in 2017 and were substituted for maximum parking requirements. In addition, for developments in the area of the city denominated as Area 1, where there is access to formal public transport services8 at an average distance of 1 km, developers need to pay a fee per parking place developed, as they approach the maximum allowed number of slots (Government of Mexico City, 2017[31]). Parking constructed is free from this fee up to 50% of the established maximum, but starts to be priced after reaching this threshold (Guzmán, 2020[32]). The fee goes to a mobility fund and is used for investing in public transport (Government of Mexico City, 2017[31]). In addition, minimum parking requirements for bicycles were also introduced as part of this legal reform (Guzmán, 2020[32]).

Transport assessments, when required; tend to focus on road availability and the impact of the new development on traffic congestion. Requiring developers to produce multimodal transport assessments, e.g. assess the availability of facilities for walking, public transport, shared-mobility services (including micro-mobility and bicycles), and infrastructure for users of these modes, instead of only roads, can help prioritise construction permits in areas that are less car dependent. It can also allow authorities to assess whether the projects are well-suited for ensuring that an important share of the travel that they generate can be undertaken in a sustainable manner, and are thus contributing to (rather than jeopardising) sustainable transport goals. Where this is not the case, developers can also be given the possibility to contribute to key transport infrastructure for sustainable modes (in alignment with long-term strategic infrastructure plans) to make the project viable (as in the case of the United Kingdom) (ITF, 2019[22]). In the United Kingdom, two types of multimodal assessment exist: 1) transport assessments, required when projects are expected to have high transport impacts; and 2) transport statements, a simplified report identifying the main transport issues and potential mitigation strategies (OECD, 2015[33]) (Box 4.2).

As discussed in Sevtsuk (2021[34]), and Sevtsuk, Basu and Chancey (forthcoming[35]), introducing requirements and guidance for the development of pedestrian impact assessments (included in transport assessments in the ULK; see below) is particularly important. After studying the impacts of annual changes in the built environment on pedestrian flows in Melbourne, for instance, Sevtsuk, Basu and Chancey (forthcoming[35]) conclude that these changes can have significant and measurable impacts on the spatial distribution of pedestrian flows. Pedestrian impact assessments for development projects are therefore an important tool for better understanding the potential impacts on pedestrian flows to ensure that planning is steered towards the promotion of walking. “Pedestrian impact assessments” can be used to produce a “pedestrian census” where pedestrian volumes during different times can be tracked. These data can be useful to identify areas where investment can be the most impactful in terms of promoting walking. Models used for the development of pedestrian assessments can also support multi-stakeholder discussions around development projects, providing an accessible platform for developers, community members and city officials to better integrate pedestrian-oriented concerns in the policy-making and planning processes (Sevtsuk, Basu and Chancey, forthcoming[35]).


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← 1. Chapter 5 also discusses how to improve the provision of public transport even in lower density areas, although reversing sprawl (and thus reducing the areas falling into this category) should be a central aim.

← 2. Infill development refers to the process of developing vacant or underused parcels within developed urban areas.

← 3. Between 190 000 and 500 000 homes could be improved according to the study.

← 4. The Greater London Authority is the administrative body in charge of the Greater London area. The Greater London area includes the centre of London; parts of the counties of Middlesex, Surrey and Kent (incorporated in 1851), and parts of the counties of Surrey, Essex, Hertford and Kent (incorporated in 1963). The Greater London area has remained mostly unchanged since 1963 (ITF, 2018[18]).

← 5. Web-based Connectivity Assessment Toolkit.

← 6. The H+T Affordability Index provides an estimate of the typical cost of housing and transportation in different neighbourhoods and compares this estimate to a household or typical household’s income. The Center for Neighbourhood Technology deems a neighbourhood affordable if a given household would spend 45% or less of its income on housing and transportation costs. This number reflects an existing rule of thumb that households should spend 30% or less of their income on housing and adds another 15% for transportation costs (ITF, 2017[23]).

← 7. Via the low-income housing tax credit, the largest source of funding for constructing and maintaining subsidised housing in the country.

← 8. I.e. excluding semi-formal services: microbuses.

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