Urban Transport Systems

In thinking about the automotive system, it is useful to itemize the reasons why individuals enjoy owning or having access to cars, and also the reasons why some people have reservations about the 'automotive culture'. What are the qualities we value in our current transport system, and what is it that needs to be changed? To answer these evaluative questions, it is necessary mentally to strip car use of its wide-ranging cultural associations and behavioral traditions, and look at the comparative benefits and liabilities of the present system.

Advantages that the public generally associates with owning and operating a personal car include flexibility and freedom, personal security and comfort, speed and the ability to carry moderate cargo loads conveniently. These characteristics have largely established the car in the dominant role it holds today. However, only the cargo-carrying ability of the private car remains a clear advantage, since in many places the other attractive characteristics of the private car are being compromised. As congestion increases, the perceived benefits of car travel become increasingly more vestigial than real.

Conversely, what are the largest perceived drawbacks to car use? A typical list might include congestion, traffic accidents and risk, air pollution and aesthetic degradation. In addition to compromises on speed, flexibility, safety and health, the road and parking infrastructure results in a landscape dominated by asphalt and concrete: highways, intersections and parking lots. Increasingly, there is a call for a different type of city aesthetic, and a lifestyle spent less within the confines of the individual, shiny metal box termed the private car.

A successful urban transport system will incorporate what people like about cars while minimizing or eliminating what they dislike (MacLean and Lave 2000). There are three general approaches to doing so, requiring successively greater changes in lifestyle and infrastructure. These are first, to improve private transport; second, to provide exemplary public transport; and third, to reduce the need for vehicular transport.

The first alternative, to improve private transport, is the most immediately promising, but is ultimately of limited application in cities. Advances in car and road design have resulted in significant cumulative change, including remarkable improvement in safety devices and emissions since the 1960s. New technologies, such as advanced composite frames and hybrid fuel-cell propulsion, promise even further gains in safety, cleanliness and economy. However, congestion and urban dynamics are more inherent problems for private transport. Smaller commuter cars and intelligent transport systems (that is, electronically monitored and controlled highway use) might alleviate these problems, but they cannot fully resolve them. While dynamic urban areas can grow in density by increasing building height, roads must grow in width to accommodate added residents and their cars - and surface area is in diminishing supply. To solve these problems more completely, the public will be forced to move away from exclusive personal vehicle use in densely inhabited areas.

The second alternative is to establish a public transport system that meets or exceeds the expectations of current car users. Although the latter half of the 20th century has often shown this to be a challenging task, none of the aforementioned qualities of car use are inherently alien to public transit. As dense urban areas continue to expand, so will the need for public transit. Currently, however, public transit is not economical or efficient for less densely built areas, and does not appear likely to replace private transport completely in the immediate future.

The third transport alternative is to minimize the need for vehicular travel in the first place. Communications and information technologies have potential to replace physical travel with digital or electronic transfers, in ways such as telecommuting. Purchases over the Internet require little travel other than that of the regular postal system (or a competing carrier). Conscientious community planners can add travel economy to convenience by locating frequently used services within walking or biking distance of residents. But even careful planning cannot obviate the need for vehicular transport in the active and interconnected functions of a modern city.

Separately, these approaches are incomplete. A satisfactory and viable transport solution must combine and coordinate all three approaches. The following proposal concentrates particularly on the first two aspects, combining personal and public transport to create an integrated, yet multimodal, approach to local passenger transport.

In our approach to metropolitan transport systems, it is helpful to realize that, often, different landscapes are best traversed by different means. In freight shipping, for example, efficient transport might require a combination of ocean freighter, barge, rail or semitrailer truck to cross various physical landscapes. The daily commuter also crosses landscapes: built environments of varying density and dispersion. These range from the widely dispersed landscape of the suburb, to the dense congestion of major transport arteries, to the level of traffic in an individual city neighborhood.

To optimize human transport, we must delineate the boundaries between these landscapes and choose transit modes suitable for each. This system does not view an urban journey as a single ride, with cars and public transit in competition the entire way. Rather, we take advantage of the fact that the different modes of transit excel in different parts of the commute: cars are unsurpassed as suburban transport, and transit is better suited to higher-density environments. By maximizing the efficiency of each stage of the journey, the system is cumulatively optimized as well.

The general model presented herein (Graedel and Jensen 1999) consists of four modes, each tailored to the dispersion of the area it serves. Suburbs are left for car travel; highvolume transit is left to high-speed public rail; city neighborhoods are serviced by tram. Each mode is connected to the others, but within its zone each is exclusive: trams do not cover suburban neighborhoods, and private cars are prohibited in the city neighborhoods. Although such a system requires riders to transfer between modes, this inconvenience is more than offset by the efficiency of each mode in time, driving effort and urban space requirements.

The backbone of this system is a radial network of high-speed transit, carrying through-traffic with infrequent stops. Two collective and distributive networks are attached to this backbone, one for suburbia and one for the city. In the city, trams with frequent stops connect each neighborhood to the nearest transit terminal. In the suburbs, riders use cars to cover the most dispersed portion of their travel route. Strategically located 'park and ride' stations allow easy and uncongested car access to a rapid transit connector, which transfers riders to a high-speed rail terminal on the periphery of the transit backbone (Figure 34.6).

Figure 34.6 A portion of a conceptual transit network for a transmodal system: a web of tram routes serves the urban core

The advantages of such a system mirror the perceived benefits of the automobile. The first is speed. The radial backbone transports passengers more rapidly than city driving speeds, without traffic or the inconvenience of finding a parking place. Second is security and comfort. By eliminating competition between modes, the system could afford comfortable and attractive vehicles, as well as adequate security systems and personnel. The third advantage is flexibility and freedom. Inside the city, the transit system has more complete coverage and requires less passenger forethought than previous systems. Since city transit is split between high-speed and street-side transit, tram routes are shorter and need not overlap. This creates simpler routes, rapid turn-around times, and thus more frequent trips and less waiting.

One function of the car thus far ignored by public transit systems is its ability to move moderate amounts of goods as well as people. Currently, passengers on public transit must carry all items with them, a task that becomes a significant inconvenience even when dealing with such common cargo as groceries. To eliminate personal cars in the inner city, public transit must efficiently fulfill this cargo-carrying function, now so well satisfied by private vehicles.

A common, if imperfect, example of such service is the airline industry, which transfers coded luggage between aircraft until arrival at the final destination. In contrast to airlines, however, public transit must quickly handle larger numbers of smaller transfers. This requires standardized bins, electronic coding and mechanized handling between transit vehicles.

Despite its complexity and cost, a cargo option opens many possibilities to simplify the movement of people and goods in the city. One can envision a city where retail stores transfer goods directly from checkout to a coded bin on the same public transit vehicle that will transport the customer. Purchases could be automatically transferred all the way to the neighborhood stop, or, for suburbanites, to a park-and-ride station, where they would be loaded into the car for the drive home. Public transit might also be designed to accommodate postal and courier services, leaving the remaining urban road space to be used exclusively by commercial delivery trucks, police, fire and ambulance services -thereby shortening vital response times.

Our conclusion is that industrial ecology has, as a field, overemphasized cars as products and underemphasized the transport system of which the car is such a major part. An emphasis on private vehicles is easier and more familiar for technologists, but will almost certainly result in unsustainable systems over the long term. In our vision, industrial ecology should address the overarching concepts and assumptions of local transport systems as well as carefully designing its details. Rather than modifying an increasingly obsolete system, we must salvage its strong points and create a new and improved response to the need for personal transit.

A wide and far-sighted view is necessary both for planning and for implementation. Cost and commitment, not technology, are the greatest obstacles to a restrictive multimodal system. Technology that satisfies the requirements of the four outlined modes already exists, but broad public support does not. The difficult commitment to abrogate the motor car within the entire central city must be supported both initially and throughout the network's development. The most critical link is the performance and acceptance of the public transit elements. By providing speed, flexibility, security, cargo space and comprehensive coverage of the initial 'no-car' zone the transit system would retain and build the support that will be required (Ausubel et al. 1998).

The process of creating a transport paradigm for the future is demanding. The pace and nature of implementation must be designed with social considerations in mind, since changing our metropolitan transport networks requires accompanying changes in lifestyle. The transition must be carefully planned and made comprehensible and compelling to all. In addition, system designers must provide for the future by building in the capability for adjusting to the changing demands of a dynamic city. This is a tall order by any standard. However, as we daily face the unpleasant alternative, the need to put the car in its rightful place - using it where it is the best option and limiting it elsewhere - becomes increasingly clear. Building a new urban transport system, as opposed to making small changes to existing dysfunctional systems, will be a long-term undertaking. Therefore, we had best start soon.

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