Active Modes and Sustainability
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Active mobility modes are all modes of transportation that involve physical activity and do not require the use of motorized vehicles. Although active modes of mobility include walking, jogging, running, bicycling, small-wheeled transport (skates, skateboards, push scooters, and hand carts, among others – also referred to as micro-mobility), and wheelchair travel, the designation active modes refers commonly to walking and biking.
Active modes are a crucial component of sustainable urban mobility development because (i) they are more energy and environmentally efficient, as they are human-powered; (ii) they promote health as they involve physical activity; (iii) they are socially active, as walking and cycling are often related to collective and socializing activities; and (iv) they are inclusive, since they are free or cheaper transportation modes facilitating the access of people to participate in the normal activities of the society, irrespective of their socioeconomic background.
Comparing Active and Motorized Transportation Modes
Transportation systems are composed of three main components: infrastructures, transportation modes that use the infrastructures, and people and goods that are transported by the several modes. Transportation modes refer to the different ways in which people and goods move from one place to another. Modes can be grouped into means of transportation that include land, water, and air transportation. The various types of transportation modes are rail, road, maritime (or fluvial), and air. Today, urban transportation means are mainly road, rail, and fluvial. The urban road transportation modes divide into active (or non-motorized) and motorized modes.
Many city centers and streets have been planned and designed with a car-oriented perspective. Driving from anywhere to anywhere has been the planning paradigm over the last decades, and motorized accessibility has prevailed active or public transportation accessibility, especially to economically active centers like central business centers or downtown (Ghel 2011; Jacobs 1961). However, the vicious cycle of automobiles, where increasing car demand asks for more capacity investments and increasing road capacity increases motor traffic (Newman and Kenworthy 1989), called for action toward a more sustainable direction.
Today, people-oriented urban planning and design are replacing the car-centered city planning. Planning for better accessibility relying on public transportation and active modes is the new paradigm, instead of planning for motorized mobility (Handy and Niemeier 1997). Furthermore, the effect of the built environment on the active travel of citizens is now recognized, and the interaction and contact between people are promoted (Handy 2005). These are fundamental elements of more lively and better quality-of-life cities with positive health impacts and higher energy and environmental efficiency (Cervero and Kockelman 1997; Ewing and Cervero 2010; Ghel 2011; De Nazelle et al. 2011; Giles-Corti et al. 2013).
The following table portrays characteristics of active modes (here, the focus is on walking and cycling) compared to motorized modes concerning a selected set of indicators of urban mobility.
Urban mobility key performance indicators for active and motorized transport modes
Speed – in km/ha
Travel time for 2 km – in mina
Travel time for 5 km – in mina
Space needed per person in vehicle – in m2/personb
Travel space needed per person (speed in brackets) – in m2/person (km/hr)b
Fossil-fueled energy efficiency – in MJ/pass.kmc
Calories consumed over 1 km – in kcal (MJ)d
CO2 emissions (gCO2-e/pass.km)c
Furthermore, energy consumption for walking or cycling has two effects: firstly, it consumes calories with positive consequences for health; secondly, it is much more efficient than motorized modes to overcome the same distance (although at a much slower speed, naturally). According to Table 1, a car will consume almost 10 or 20 times more energy to overcome 1 km than someone walking or cycling, respectively. If compared with buses, the differences are three or five times bigger, respectively. Moreover, if fossil fuels power motorized vehicles, CO2 will be emitted, and private cars are far more polluting than buses, trains, or light rail.
In the end, these indicators highlight the reasons why resourcing to active modes together with public transportation can be so compelling for a more sustainable urban mobility.
Social, Health, and Environmental Benefits from Active Modes
The growing awareness of the need to reduce the use of cars and to shift to active transport is mostly driven by the significant individual and collective benefits for a more inclusive society, health, and the environment. There are many possible effects, some of which are extremely difficult to evaluate, for instance, impacts on the social fabric of a community, on the sense of well-being of the population, and even on the crime rate. Other impacts were reliably evaluated and quantified, such as health impacts of the physical activity and air pollution (Rabl and Nazelle 2012).
Researchers in Auckland, New Zealand, studied the costs and benefits of transforming urban roads over the next 40 years, using best practice such as physical separation on main roads and bicycle-friendly speed reduction on local streets (Macmillan et al. 2014). The authors concluded that $NZ10 to $NZ25 would be saved for every dollar spent on bicycling infrastructure. Interestingly, these gains would include the savings in reduced investment in road infrastructure as fewer cars would circulate and wear them out.
Living in neighborhoods more “walkable” and “cyclable” (with sidewalks, bike paths, parks, higher density, and stores within walking distance) has been associated to a better quality of life, mostly related with healthier weight status and better mental health (Giles-Corti et al. 2013; De Nazelle et al. 2011; Pucher et al. 2010; Saelens et al. 2003; Sallis et al. 2009). While more physical activity leads primarily to weight losses (and reduction of weight-related diseases like obesity), positive impacts of active modes on mental health are less evident. Still, Evans (2003) mentions that socially supportive networks influence mental health indirectly and these are greater in areas with higher pedestrian connectivity or more meeting areas. Furthermore, there is evidence of more joy experienced by Dutch cyclist commuters in the study by Keck et al. (2007).
Streets’ pedestrianization is today frequent in many cities worldwide (i.e., conversion of the streets with motorized road traffic into walkways or plazas without motorized traffic). However, the emblematic case of the Times Square in New York is a clear example of the benefits of social interaction of walkable environments where walking, strolling, and staying generate interaction, besides the positive economic effects on retailing (The City of New York 2010).
The indirect benefits that derive from active modes are challenging to measure. Those include the reduction of road repairs and maintenance, avoided costs due to greenhouse gas emissions, health care, and the increase in bicycle tourism and industry. Retail and real estate business also experience positive effects with the implementation of urban plans that promote walking and bicycling in their zones. Campbell and Wittgens (2004) estimated that the annual economic benefit of active transport is $3.6 billion per year with the potential to reach $7 billion with a 15.2% modal share increase.
Active Modes and Sustainable Urban Mobility
As the world moves toward a global population of nearly 10 billion by 2050, most of which will be in urban areas, today’s challenges for cities (for instance, health, air quality, noise, and social justice), are likely to increase (UN Habitat 2016). Mobility is a crucial dynamic of urbanization, as travel demand (i.e., every trip made) derives from every socioeconomic activity needed or wished to be undertaken. As such, the required infrastructure to provide mobility always shapes the urban form of cities, that is, the way the territory is defined by roads, transport systems, spaces, and buildings. Despite the increasing level of urban mobility worldwide, access to places, activities, and services has become increasingly difficult. The urban sprawl, by which there is a horizontal, low-density growth of cities over vast areas, implicates longer distances between functional destinations such as workplaces, schools, hospitals, administration offices, or shopping amenities, leading to a growing dependency on motorized transportation to overcome such distances and, eventually, private car-centered mobility.
Generally, half of all urban car trips are less than 5 km (Dufour 2010). As referred previously, walking is a competitive alternative for short trips. For example, 80% of Amsterdammers have stated that they were willing to walk up to 1 km, a percentage that decreases significantly to 25% when considering distances of 1 to 2.5 km and 3% in the case of 2.5 to 3.7 km (Meijer 2012). As such, walking and cycling can cover a very significant part of daily trips in all cities.
Planning endeavors and policies are aiming at distorting this modal split that focuses on motorized transport and has been established at this state for the past decades in most parts of the world. Worldwide, many different institutions have prepared policy and design plans to promote walking and audits indicating the right strategies that can guarantee the development of walkable urban areas (Abley and Turner 2011; Ryus et al. 2014, among others). The practice has shown that investments in pedestrian networks can favor the share of walking as a mode (Lamíquiz and López-Domínguez 2015); likewise building cycle networks and facilities triggers latent demand of regular bike trips, following the motto “build it, they will follow” (Macmillan et al. 2014).
Many European and Canadian cities are following the path to the efficient development of active modes and showcase how to plan and build cities for pedestrians and cyclists instead of catering for motorized transport. In an era where the shared economy is rising, the integration of actives modes in urban and transport planning is more evident than ever. The societies adopt more efficient and sustainable mind-sets: all environmental, social, and economic benefits of transport actions are in the center of interest.
In this context, the objective behind the initiative for the development of Sustainable Urban Mobility Plans (SUMP) in the European Union is the efficient amelioration of transport-related problems following a participatory and integrated approach; a pledge for sustainability; a clear vision, objective, and measurable target; and a review of transport costs and benefits, building on existing practices and regulatory frameworks (ELTIS 2014). Among many concepts, sustainable urban mobility per se considers two crucial planning concepts as alternatives. The first one relies on reclaiming traditional neighborhoods and making them more walkable with proximate daily activities; the second one is transit-oriented development (TOD) that aims to boost the activities around main transport interfaces (which are main urban transport hubs, like railway, bus, or metro stations), where the “last mile” trip relies on active modes. Importantly, TOD restricts private car use and promotes active modes.
This urban mobility framework approach has been applied in many case studies (CIVITAS and EPOMM networks). Active modes are a cost-effective way to alleviate congestion problems in central areas with dense activities. Specific policies have ameliorated this bottleneck by banning the entrance of vehicles into the city center, leaving the space available to pedestrians, and improving the quality of life and the execution of activities of all inhabitants, employees, tourists, and local agents. The reduction of parking areas in public spaces assists as well as the promotion of active modes by impeding motorized transport.
Traffic calming approaches have also been effective in the attempt to favor active modes and especially walking. For instance, many cities encourage changes in traffic flows by restricting the speed limit at the level of neighborhoods or the city center. Hence, the so-called 30-speed areas are developed to facilitate the sharing of streets by both active and motorized modes, in harmony. Pedestrian and cycling signaling is also used to enhance safety, by reserving space and time for active modes while increasing the drivers’ awareness of active modes in the area. Regarding the design of the infrastructure, the removal of barriers in walkways and the reductions of pedestrian crossing distance are means to enforce walking, while many carriageway rearrangements are useful to spare space for cycling through bike lanes, counter-flow lanes, or bike paths.
People nowadays show a propensity to favor active modes against motorized transport given the proper conditions. A study of the American Planning Association (2014) indicated that “81% of Millennials and 77% of Active Boomers say affordable and convenient transportation alternatives to the car are at least somewhat important when deciding where to live and work.” In Canada, 82% and 62% of people have stated that they are willing to walk and cycle more instead of driving (Campbell and Wittgens 2004). A study in the USA, assuming that 100 employees would shift from driving to active modes at a typical urban worksite, estimated that each commuter would benefit 8.75 $/trip, considering the total cost of trip expenses and accounting also for the costs of environmental and health damages, time losses, and safety casualties (Litman 2018).
Overall strategies and practices have been identified to integrate active modes in urban and transport planning as priorities. Proper infrastructures need to be provided to achieve the maximum benefits of active modes. Next, planning and design principles for active mode infrastructure are presented.
Facilities for Active Modes
This entry presents the main features of active modes, how active modes relate with infrastructures, and which are the implications for planning and design of facilities. The entry is divided into two sections for “pedestrians and walkways” and “cyclists and bikeways.”
Pedestrians and Walkways
Ultimately walkways may be any space wherever people can walk, to the extent that they are physically able to do so. Walkways divide into outdoor and indoor facilities, whether fixed or moving. Outdoor facilities include sidewalks, crosswalks, intersections, bridges, accessible sections, trails, and indoor facilities that may be tunnels or corridors (fixed or moving) connecting to the surface or underground areas.
As for road traffic, the pedestrian traffic flow diagram portrays the collective behavior of pedestrians within walkways also reflecting the interactions between one another. Importantly, speed decreases as space per pedestrian decreases, and there is a maximum flow for the infrastructure analyzed which peaks at an estimated mean of 1.34 m/s, although variation occurs in a range of 1.08 m/s (Saudi Arabia) to 1.6 m/s (UK and USA) (Daamen et al. 2005).
LOS levels of pedestrian movements
Related to the pedestrian, including sociodemographic profile (e.g., gender, age), physical conditions (e.g., any disabilities or health state), and personal psychology, culture, and lifestyle (which relate to preferences, habits, and attitudes)
Related to the trip, including its purpose, the time of the day, the number of people walked with, how well the place is known in navigation, and available alternative modes
Related to the built environment and its facilities, including its walkability, the effectiveness of the wayfinding guidance, and the land uses that attract people to the area
Urban planning and design have a decisive role to play and must ensure that pedestrians can move seamlessly around spaces with adequate guidance. In this context, the concept of walkability (Bradshaw 1993) has been introduced to express the extent to which an urban environment is more accessible and attractive to pedestrians (Abley and Turner 2011) and many tools have been proposed to assess it – for example, Walk Score (Front seat 2011), Pie model (Singleton et al. 2014), or IAAPE (Moura et al. 2017), among other tools. Certain qualities describe walkable environments such as legibility, imageability, enclosure, human scale, transparency, linkage, coherence, and complexity (Handy 2005) allowing the use of respective indicators for the assessment of its walkability which are connected, convivial, conspicuous, comfortable, convenient, coexistent, and committed (Moura et al. 2017).
Furthermore, pedestrians collect information continuously from different sources (i.e., signaling, information signs, other agents in walkways, among other stimuli), but they also need well-designed architecture to assist them (Rüetschi 2007). Among other techniques, Space Syntax is emerging as a useful and intuitive tool (Hillier 2005) to support urban and transport planners in the design of the city. In this way, with a proper built environment configuration, orientation can be facilitated, and walking is encouraged. Also, wayfinding, the process of finding one’s way in the geographical or built environment and knowing how to get to the required destination (Fewings 2001), comprises a requisite for efficient pedestrian space.
Cyclists and Bikeways
Cycling is clean, quiet, economical, and accessible. Technological developments are making it increasingly efficient and more comfortable. On short-distance urban routes (up to 5 km), it is faster than cars, especially under congestion. When combined with other modes (e.g., public transportation or shared solutions), bicycles can cover broader areas, effectively. The potential of cycling, as a means of transport for daily commutes to the workplace, school, or other regular activities, such as leisure activities, should be promoted in the new urban sustainable development paradigm (UN Habitat 2016).
Bicycles are well-suited for trips up to 7 km, pedelecs (which are bicycles assisted with a small electric engine) even for trips up to 15 km. Like for walking behavior, cycling depends not only on the bike users’ characteristics but also (and perhaps more importantly) on the cycling facilities and network provided. For that, it is critical to know the population of potential cyclists and target measures more accurately to meet their needs and requirements.
Current cyclists, who cycled in the past month for commuting and would cycle again during the next month and are typically more proficient and physically able to cycle
Potential cyclists, who cycled at least once in the near past (e.g., 12 months) for leisure or commuting and would cycle again if some conditions were fulfilled or someone who did not cycle in the near past but is willing to do it although not convinced yet
Non-cyclists, who did not cycle in the near past (e.g., 12 months) and are unsure if they are willing, or are unwilling, to shift to cycling in the near future
Starter cities have few cyclists, little infrastructure, no cycling culture (i.e., cycling is considered unsafe and not respected by motorized vehicle drivers), and car-oriented urban planning and design. Current cyclists in starter cities may quit if conditions do not improve or deteriorate.
Climber cities, cyclists are present but the potential bicycle modal share (i.e., the percentage of regular trips made by bicycle) has not yet stabilized, and considerable progress has to be made to encourage more modal shifting to regular cycling.
Champion cities or “bike-friendly” cities, cycling is a regular practice and embedded in the local mobility culture. Here, cyclists expect a high level of quality of infrastructure, and the challenge is to maintain the cycling modal share by improving the quality, comfort, and security of cycle networks and facilities.
Many guidelines are available to plan, design, and promote cycling in cities (NACTO 2014; Austroads 2014; Transport for London 2014; Australian Cycling Promotion Foundation 2018, to mention a few). These manuals are entirely consistent across the board in regard to the recommendations for planning and design of the cycle network and facilities. Here, we present some basic guidelines on the expectations of an effective cycle network (i.e., providing accessibility within the urban area) and cycle facilities (i.e., ensuring comfort and safety, overall).
Bicycle network features (Austroads 2014)
Minimal risk of traffic-related injury, low perceived danger, space to ride, minimum conflict with vehicles
Infrastructure should form a coherent entity, link major trip origins and destinations, have connectivity, be continuous, signed, consistent in quality, easy to follow, and have route options
The route should be direct, based on desired lines, have a low delay through routes for commuting, avoid detours, and have efficient operating speeds
Lighting, personal safety, aesthetics, integration with surrounding area, access to different activities
Smooth skid-resistant riding surface, gentle gradients, avoid complicated maneuvers, reduced need to stop, minimum obstruction from vehicles
The dynamic envelope of cyclists for different cycling situations (Transport for London 2014)
Dynamic envelope width (m)
Dynamic envelope of a standard cyclist, taking into account “wobble room” when moving
The indicative maximum dynamic envelope of the widest cycle types, assuming less “wobble room” for types with three or more wheels
The recommended minimum clearance between the furthest extremity of a moving motor vehicle and the outside of the dynamic envelope of a cyclist at 30 km/h or less
Recommended minimum safe clearance at 50 km/h
The recommended clearance between dynamic envelopes of cyclists moving in the same direction
Logically, the higher is the place function of streets and avenues, the more the cyclist has to be protected since speed and flow of motorized traffic tend to increase.
This entry began with a short definition of actives modes. The following four entries aimed at complementing this definition by providing basic and crucial information on the most widely used actives modes, i.e., walking and cycling. In the context of the UN Sustainable Development Goals, this entry is instrumental, since it explains in depth the term “active modes” within the context of sustainable urban mobility. The term relates to the Goal 9 “build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation” and, more particularly, to the sustainable development of urban areas that are increasingly concentrating population and economic wealth while facing heavy challenges of sustainability.
This provides an in-depth understanding of the term while giving access to a complete list of up-to-date references that gathers together the main contributors to the topic, both from academia (where most cited papers were preferred) and the industry (resorting mainly to reference international institutions).
As a final note, pursuing people to move from motorized transport to active modes, namely, leave the car and walk or bike, is not an easy task. Mobility habits are part of culture and changing culture may prove to be an arduous task. However, the practice has shown that building the adequate infrastructures and facilities for active modes and entailing proper communication of their benefits can convince passengers to change their habits and engage in more active mobility. For that, school programs are a sustainable mobility education which are a crucial piece of any sustainable urban mobility development, preferably starting with younger generations beginning as soon as elementary school.
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