A Primer On Urban Mobility
Updated: 2 days ago
by Joel Luna. Published in the Philippine Daily Inquirer, November 2019.
I was privileged to contribute a series on Urban Mobility at the Philippine Daily Inquirer the past several weeks. Sharing all 3 parts here. Thank you, PDI!
Part 1: The Geography of Urban Chaos
Real estate’s tired but enduring 3 principles of Location, location, location will always be universally relevant. But what determines good location? Intuitively, these are places enjoying a good amount of traffic and visibility: at crossroads, at points of changes in modes of transport or shifts in direction, at places of good accessibility and connectivity. These attributes contribute to concentration and agglomeration of activities, which are the essence of cities.
Cities are networked systems. They behave in the same way that the virtual world of social networks and computer systems behave: they are hubs that connect to other nodes through links. The greater the number of links a particular node or hub has, the more it attracts new links (Law of Preferential Attachment in Networks). In the physical world, mobility systems such as roads, transit, air and sea ports are the links that connect people and bring them together to the hub called cities to enable the exchange of goods, services and ideas. Within the cities are smaller networks of hubs, nodes and links organized in a certain self-sameness of form and functionality. The best locations are hubs with the most links enabled by transportation. And just like social networks, the best sites attract more links and connections. Unfortunately, in the physical world, the number of connections is limited by the capacity of the links (transportation) and thus, the downside of good locations, as we presently experience it, is congestion and longer commute times.
Geography is the DNA of Urbanism
Part of what drives the capacity of the urban mobility is the lay of the land. Metro Manila, for instance has Laguna Lake and the Montalban mountains to the east and Manila Bay to the West. This location, while ideal during the time of water transport and before the city had to grow exponentially in size, created constraints in the expansion of the metropolis and concentrated urbanization and mobility in a confined space determined by topography. In some portions of southern Metro Manila, the land mass is just around 8 kilometers wide. If you consider the areas of restricted access along that narrow waist such as gated subdivisions, the airport and the former military bases which further constrained the transport corridor, then it is not surprising that congestion happens along South Luzon Expressway during peak hours. Similarly, in Metro Cebu where the city is confined to a narrow stretch between the sea and the mountains, urban development and land transport follows a linear path, thus the congestion now experienced in the city. While the challenges of geography are not insurmountable and can be addressed by creative land use planning, better infrastructure or new forms of mass transport, these solutions will still, ultimately and inevitably, have to contend with the physical limitations of the site.
Form Follows Infra
The size of cities is determined largely by its transport shed or its commuting distance. Cities were more compact when the primary mode of travel was on foot. As technology allowed for faster mechanized transport, the limits of the city have increased, absorbing the hinterlands into ever larger conurbations. Paradoxically, while transport’s goal is to ease mobility and reduce congestion, they also consume space. And in highly urbanized areas, where transport is most needed due to serve a high number of people, space is very rare and very valuable.
Most metropolitan areas react to congestion by adding more highways, more road lanes or extending road networks into farther areas. This, however, has mixed results: adding more roads to an already congested network can result to more congestion and longer travel times, a phenomenon known as Braess’ Paradox. The paradox is also more humorously captured by Lewis Mumford when he said, “Adding car lanes to deal with traffic congestion is like loosening your belt to cure obesity."
The key factors behind this dilemma has to do with society’s behavioral tendencies, in particular our dependence on specific paths and modes of transport (i.e., cars) both of which are aggravated by the fact that road usage is essentially free. The combination of these 3 elements creates the recipe for negative externalities: the use of a congested road by any individual will adversely affect others. Improving economic conditions and an increasingly affluent population will tend to increase car ownership and therefore reinforce automobile dependence leading to congestion which prompts adding more road capacity in a vicious loop. Providing mass transit along the same established vehicular routes, while it is a step in the right direction, is often not a complete solution since it reinforces path dependence. Perhaps the way to begin addressing the urban mobility dilemma is to deal with the key factors that create it: reducing mode dependence and path dependence.
Part 2: Dependencies and Induced Demand
Last week’s story in the Philippine Daily Inquirer on the traffic woes on SLEX (https://newsinfo.inquirer.net/1170156/24-km-crawl-on-slex-adds-to-agony-of-metro-commute) highlights the daily struggle of all commuters nowadays. In fact, the snail pace of traffic in the city is no longer news to us and is endured with a sense of hopeless acceptance as part of living in Metro Manila.
The story highlights a common ripple effect of traffic, where the closure of a lane due to construction caused a queue of vehicles stretching from Alabang to Sta. Rosa Laguna. The daily congestion has caused some motorists to shift to other routes (say Alabang-Zapote Road) and create congestion there in a classic butterfly effect. The phenomenon is all too familiar: a small aberration (say a stalled vehicle on EDSA) can create chaos on other links in the network and cause a system-wide state of paralysis, now popularly known as Carmageddon.
The cause behind the congestion, of course, is the surge of vehicles during specific times of the day: the daily tide of commuters and motorists who flock to the city center during the morning and reversing in the afternoon in a constant ebb and flow. And the congestion isn’t limited to road use. Public transport is not spared from this and transit users also experience horrendous congestion, shortage of rides and queues during peak hours. This pendulum movement of traffic is basically result of spatial interactions between different activities. In other words, Accessibility is a function of land uses and their distances from one another. Distance, in the context of transportation, is the cost of moving from one place to another and can be measured in terms of length, time, economic cost or energy used. The objective of mobility, therefore, is to reduce distance, or more precisely, to reduce the friction costs of distance.
In an urban setting, travel time has become a more relevant metric of distance as this is the friction cost that is most felt (and lost) by commuters and motorists as a result of traffic congestion. Thus, most infrastructure projects aim to reduce travel time to the city center. While well-meaning as an objective, herein might lie the critical flaw in assumption that leads to dependence on certain paths and modes of travel as it sometimes translates to adding additional car lanes to the already congested route (Braess’ paradox).
Path Dependency and Mode Dependency
Land use is arguably the single most important factor that influences mobility. Former City Planner for Vancouver, Brent Toderian, once said “The best transportation plan is a good land use plan.” Land use, or more specifically, the 3-dimensional spatial arrangement of various urban places, influence patterns of mobility. Whether most people drive, use transit, or walk in the city, is often a result of land use decisions. Gated communities, for instance, with their restricted access, sprawl and homogeneity, encourage the use of cars for even the most basic trips.
These types of single-use enclaves such as gated villages, industrial estates, military camps separate activities from each other. Their size and exclusivity creates impenetrable barriers that prohibit public access and public transport and limit direct and alternative pathways to other areas, funneling traffic to the edges and thus limiting connectivity to a few specific routes and thereby also planting the seeds for path dependency.
Thus, the dependency on specific paths and travel modes are often not a result of poor transport planning, but rather and more fundamentally, due to poor land use planning. The idea of exclusivity, whether in terms of land utilization, road use or vehicular use has far reaching implications on transport and has eliminated various opportunities of shared use and access.
Move People, Not Cars
Interestingly, despite the view that there are too many cars in the metropolis and not enough public transport, 68% of motorized trips in Metro Manila are made by public transit. And 30% of these motorized trips are only for a distance of less than 2 kilometers: the so-called, first and last mile connection. Metro Manila has over 15 different forms of public transportation, some of which are small-scale, informal systems. These modes address the demand for mobility in places that are not reached by formal transit. While mass transport routes tend to mirror vehicular routes (path dependency), small scale transport addresses the gaps, moving people and goods along feeder routes, handling the start and end legs of the commute.
If travel time is considered a friction cost of mobility and if traffic congestion results in actual economic and productivity losses, then why is the use of congested roads free? And what if instead of asking “how can we move people faster from A to B?” we reframe the urban mobility question to, “how can we provide ease of movement for people?” After all, travel time is not the sole measure of the friction cost of distance. Length, or the actual kilometers travelled, can be shortened by bringing destinations closer to each other, to a point where walking becomes a real choice for mobility. This again, is a function of land use planning.
Part 3: Towards Walkable Cities
A colleague at our firm leaves from her house in Marikina before 3:30 am to make sure her commute is under 2.5 hours. If she leaves later, she risks extending here travel time to 4 hours. Thus, on a good day she would spend 5 hours commuting from home to work and back. Her plight is not uncommon and she is paying the price of having too many vehicles leading to the same destination, competing for limited road space. Metro Manila is 4 hours away from Metro Manila.
But if road space is scarce, then why is it’s use free? Who is paying for all the traffic congestion? Definitely not the motorists because their use of the road is free and is, in fact, subsidized by non-motorists. A motorist’s use of a road causes negative impacts or costs to others living in the city in the form of congestion, pollution, noise, greenhouse gases, etc., which are referred to as negative externalities. In other words, the non-motorists are absorbing the costs of congestion. Part of the reason why such negative impacts exist is because road usage is free and therefore do not account for the real costs of their use, effectively causing the public to pay for the use of the roads by motorists.
One of the ways that other cities have addressed the issue of traffic congestion is to internalize the negative externalities of congestion. Some cities have recognized and addressed this by charging for the use of the road through congestion pricing. In cities such as London and Singapore, cars entering the city center on peak hours are charged fees as part of demand management to relieve traffic congestion. In so doing, external costs are internalized by making the motorists pay for the use of the road and for the costs they impose on others. Such strategies aim to shift motorists to travel during off-peak or to take transit and thereby reduce congestion. Studies have shown that a reduction of as low as 5% of vehicles in a congested urban highway allows traffic to flow more efficiently.
The objective in internalizing the cost of road use is to reduce cars on the street. And if we are to reduce the number of cars going into the city, then there has to be an alternative to the use of the automobile. Interestingly, 30% of motorized trips in Metro Manila are less than 2 kilometers in distance, a 30- to 40-minute walk. Thus, if even a fraction of those 2 km motorized trips in Metro Manila shift to walking or biking, it is conceivable to realize a perceptible relief in road congestion, freeing up some capacity in the network for commuters coming from farther away (say Marikina)-- a positive butterfly effect.
The good thing about severe traffic is that it prompts some motorists to consider alternative methods of moving around such as taking P2P or ride sharing or simply walking. The key, of course, is in ensuring that these alternatives are comfortable and safe for those using them. Many cities have already implemented pedestrian or bicycle infrastructure to encourage more people to walk rather than drive. Elevated walkways provide uninterrupted and protected pedestrian corridors. Other places have provided dedicated pedestrian greenways (e.g. Bonifacio High Street) or have gone on road diets where car lanes have been reclaimed for sidewalks, parklets, transit or bike lanes. Some cities have even gone to the extent of closing streets from cars altogether and reclaimed the streets for pedestrians. Barcelona, for instance, reconfigured their city network into superblocks, keeping cars at the edges and creating pleasant and safe areas for walking and biking, thereby bringing life to the streets and encouraging businesses, cafes and restaurants in the process. We need to keep in mind that all transit users are also pedestrians. Thus, by enhancing the pedestrian experience we could also be encouraging transit use.
Faster Speeds or Shorter Distances?
An important point to consider, though, is that physical distance is the key factor that transportation aims to overcome, regardless of the mode of travel. Throughout history, transport has used speed as the means of overcoming distance. Thus, most innovations in transport focused on faster modes to shorten travel time while allowing distances between destinations to increase which. But what if the goal of transport is to shorten the distance between origin and destination and not just to shorten travel time? And what if the distances between the places people need to regularly go to are close enough to walk? This is the principle behind compact and dense mixed use environments: bringing people and activities close enough to a point where walking becomes a good choice for moving around and where people are encouraged to live a more sustainable lifestyle. From a planning and property development point of view, this requires a drastic rethink of how we design our cities and one that requires putting pedestrian mobility first and vehicular mobility last. This means putting more real estate to enhance the experience of active mobility rather than adding more infrastructure to serve cars. Fred Kent, founder of Project for Public Spaces said, “If you plan for cars and traffic, you get cars and traffic. If you plan for people and places, you get people and places.” After all, what better way is there to experience any city than by foot? Perhaps, once we have learned to focus more on improving the pedestrian experience with wider sidewalks, shade trees and outdoor cafes and rediscover our natural form of mobility, we may likewise rediscover the charm of our city.