More mobility with less traffic

The car acts like a drug: It opens up new dimensions of mobility, but when used to excess has considerable side-effects which choke the mobility it affords.

Table of Contents

 

Arguments for Sustainable Mobility

A close analysis of the concept of mobility shows that mobility is not the same as traffic. One and the same level of mobility can be achieved with much or with little traffic. The determining factor is the range of activities offered within an individual's radius of action. If we wish to safeguard mobility for the long term, we have to improve opportunities for activities near the home rather than widen the radiuses of action.

The car rules everyday life

The car could be called a drug abused for mobility-boosting doping  - to use a common phrase from competitive sports. The numerous parallels with drug use and abuse are amazing. The car opens up new dimensions - in choosing where we should live, work and shop, how to spend our leisure time, or simply in the way we traverse space.

Like all potent drugs, the car has considerable side-effects. Especially the residential environment is afflicted with them: trees and green spaces, the post office "at the corner", neighbourhood shops disappear, squares and front gardens are converted into parking space, sidewalk cafés lose their customers, balconies become unusable, children cannot go outside unaccompanied, carrying on a conversation while window-shopping is almost impossible for all the traffic noise. On some days, advice is issued to the population to refrain from doing outdoor sports and to sensitive people not to leave the house at all. Lucky for them, the noise is reason enough to rarely open the window, "denn seien wir ehrlich, Lüften ist (fast) immer lebensgefährlich" as Erich Kästner might have said. The result of this development is the need for more "auto consumption". When the good things nearby are destroyed, attractive destinations such as quiet "local" recreational areas or shops catering to one's daily needs become more and more remote. A vicious circle.

This trend, this growth in traffic, is interpreted by some experts as growing mobility among the population and hence as a positive development. This is done because mobility is confused with traffic and often even with car traffic. An unbiased analysis shows, though, that mobility and traffic are not the same thing. More mobility can also be achieved without more traffic.

 

What is mobility?

The term mobility is commonly used to describe both the movability (possibility to move) and the actual movement of people and objects.

Of interest here is that portion of mobility which generates traffic, or transport-related mobility (see Diewitz, U., Klippel, P., Verron, H.: Der Verkehr droht die Mobilität zu ersticken, in: Internationales Verkehrswesen, no. 3, 1998, p. 72-74). This transport-related mobility - simply referred to in the following as mobility - comprises

  • movement from one location outside the home (for people) or outside the business (for objects) to another, creating traffic in public space used for transport (road, rail, air space, waterway),
  • movement directed towards a specific geographical location, e.g. home, workplace, stadium, production facility, warehouse, department store, with that destination invariably also being the place of activity, e.g. staying at home, working, running, producing, storing, distributing.

Mobility can also be quantified. The more activity objectives are reached, the higher the mobility. This definition implies that reaching activity objectives is the decisive factor for mobility, and not the distance travelled. It links mobility with the activities individuals seek to pursue (to meet their needs) and does not include a valuation as to whether these are, say, desirable or undesirable, necessary or unnecessary.

Basic mobility pattern

Ms. Allosa lives in the city, in a flat in an old tenement building. She works in an electrical shop 4 kilometres away from where she lives. She usually goes to work by bike. Going home from work, she stops by the market to buy bread and vegetables. - A typical mobility pattern with the three activity objectives working, shopping, staying at home.

 

Potential and realised mobility

Mobility is not completely described by the number of objectives reached. The meaning of the term 'transport-related mobility' encompasses both movability and movement, the capability to reach and the actual reaching of objectives - in short: potential and realised mobility. As will be shown, this differentiation is essential for the proper treatment of the mobility issue, and it allows the definition of mobility to be extended accordingly:

The more activity objectives can be reached in the time available, the higher the potential mobility. The more activity objectives are actually reached, the higher the realised mobility.

werden, um so höher ist die realisierte Mobilität.

Potential and realised mobility

Ms. Allosa lives in a city district with many and diverse amenities. When she wants to post a package, she can choose between three post offices located within her average range of movement. The closest one is only a five minute walk from her flat, but it is always very busy so that she can expect a long wait. That is why she usually opts for one of the post offices a little farther away. By bike, it takes her 10 minutes to go to the next (never very busy) and 15 minutes to go to the third (a very nice-looking young man always waits on her there). The fact that several post offices are within her reach does not increase Ms. Allosa's realised mobility. She will only go to one post office to post her package. Yet, knowing she has a choice makes her feel better.

Mobility of people

In the following, mobility of people is used as an example to show that the above definition is of quite practical relevance. Extrapolating the examples to the mobility of goods is possible, albeit not in a trivial sense.

Potential mobility

Potential mobility is a function of the density of activity opportunities available within the individual's radius of action. Hence, potential mobility is above all a measure of the quality of activities and thus a measure of the quality of life: Do I have the option to get a better-paid job ? Can I choose between different pubs ?

Potential mobility is mainly influenced by two factors: the density and diversity of near-home activity opportunities, and the available transport mode.

Life in an urban area, as compared to a rural for example, enhances the potential mobility in that it offers many and diverse possible destinations, while travel by car does so - for distances in excess of about 3 km - by its relatively high speed which extends the radius of action.

 

Factors influencing mobility

Ms. Allosa thinks about how she can get back to having the amenities and options she used to enjoy, and decides to buy a car. Now she has considerably more activities to choose from again. Even the p ost office with the nice young man is not too far away. Everything is almost like it used to be. Sometimes, though, Ms. Allosa feels bad about contributing to the very noise and pollution she tried to escape by moving out of the city.

Urban settlement structures and auto availability both lead to greater mobility, but have different side-effects:

Urban settlement structures

  • ensure high potential "mobility of short distances",
  • make mobility socially acceptable because it is not tied to auto availability,
  • lead to a continually accelerating, positive automatism of less traffic, improved quality of the urban environment, gains on the part of environmentally sound transport modes, less traffic...

The car

  • ensures high potential mobility by broadening the radius of action ("mobility of long distances"),
  • can offset, at least in part, the disadvantages which rural areas have in terms of mobility,
  • initiates a continually accelerating, negative automatism of car traffic, poorer conditions as regards housing, the residential environment and leisure activities, more car traffic...,
  • or "auto-mobility" usually has negative repercussions on the settlement structure, causing a degradation or even displacement of opportunities for near-home activities. The greater mobility which the car affords is

Auto-mobility and settlement structure

It has been several years now that Ms. Allosa has lived in the country. She enjoys the green surroundings and the wide open sky. Still, she asks herself more and more often whether she should not move back to the city. She finds that even the last remaining shops in the neighbourhood have disappeared. Whatever she sets out to do - buy bread, post a package, go to the movies - she needs the car. She even depends on it - or the bus - when she takes her 3-year-old daughter to k indergarten.
Ms. Allosa has come to see her car as a crutch which she uses out of necessity, but reluctantly

 

Realised mobility

Realised mobility is quantified by the number of activity objectives actually reached. The variable "number of trips" used in statistics to express mobility is identical with the number of activity objectives.

Changes in potential mobility have on average a relatively minor impact on realised mobility. Since it was begun in 1976 in the Federal Republic of Germany to not only record motorized trips, but also trips on foot and by bike, trip number has only increased slightly, if at all. The average is a little more than 3 trips per person. A similar figure was determined as early as the 1920s for Berlin.

However, those who equate mobility with auto-mobility come up with an impressive increase in mobility. Trips by car grew by more than 100% between 1960 and 1994 alone.

On the relationship between traffic and realised mobility

Average trip length provides the quantitative link between traffic and mobility: kilometres travelled 1 = number of trips * average trip length (1 Kilometres travelled, measured in persons * km / year or tonnes * km / year. Data on this and the utilization rate of vehicle capacity is used to calculate traffic volume, measured in vehicle kilometres per year

With the number of trips - and hence mobility - remaining constant, kilometres travelled can increase or decrease depending on the trend in average trip length. Both developments are possible. Today, the strategy of choice is to rely on ever faster means of transport. They enhance accessibility by facilitating the traversal of space, and in so doing destroy it. Mobility in this case is associated with more travel ("mobility of long distances"). The associated traffic chokes not only people, but also their mobility.

A mobility that is sustainable improves accessibility through the concentrated provision of activity opportunities, i.e. by using space more intensively while simultaneously upgrading it. Mobility in this case is associated with less travel ("mobility of short journeys").

In the long term, safeguarding mobility or increasing it will only be possible with less travel, i.e. with a mobility that is based on short journeys. Since measures to improve settlement structures take long to show an effect, it is high time for a new transportation and settlement policy. The course towards a better utilization of space and away from the degradation of same.