urban transport

Parking charges and parking restrictions are today the most cornmon methods of restraining traffic in large

towns (see Hebster, 1986, p.146). But if there are not enough parking spaces, car drivers would park on pavements or in double lane, hence increasing congestion. On the other hand, "if parking provision is over-generous, more people may be encouraged to drive ... so congestion is increased" (Webster, 1986, p. 146). But in absence of physical restraints to flows of vehicles, the traffic could be left unaffected and some parkings could remain empty. For instance "Villa Borghese" car park in Rome remained empty as long as cars were allowed to go through the city centre (see Fontana, 1987, p.5).

Therefore parking charges and parking restrictions may not completely succeed in decreasing congestion.

An irnportant reason for the increase in private traffic is that public transport is not satisfactory:

people consider more inconvenient and expensive to use bus services. Indeed the cast of a journey is not only the running cast of the car or the bus fare, but it is also the opportunity-cost of the time employed, "the

money value the traveler attaches to the time his trip requires" (Mohring, 1972, p.591). In presence of high

degree of congestion, people prefer private transport which on average implies a shorter time - in term of

waiting time and partly in term of travelling time - for a given journey. Potential bus passengers do not travel if the sum of the opportunity-cost of the time and the fare is higher than the value placed on the journey, or they switch to private transport.

Due to congestion, bus services face high operating costs; in fact it is necessary a longer travelling tirne per given unit of service provided to the public. Italian municipalities have decided to increase fares and to reduce the number of bus journeys, in order to balance the budget. This policy may cause a substitution effect towards private transport.

Under these assurnptions, it is difficult to understand the utility of marginal cost pricing for bus fares.

Moreover, bus services are inferior goods (see Mohring, 1972, p.602: "As real incomes increase, the demand for these services will undoubtedly continue to decline"), instead the private transport consumption raises with income (see Istat, Annuari Statistici, 1977-1984).

The preference for the private transport base itself on subjective judgements about its characteristics and on the influence of advertising and of wont. If a means of transport have not certain characteristics, it will be left without any market (see Tomasini, 1969). In the opinion of many people, car is the best means of transport, because is more useful, more comfortable anà faster than the others.

Therefore its characteristics could make well to tolerate an increase in the running cost. In general, the increase in a good price causes a reduction in its consumption and an increase in the consumption of a good succedaneum. We suppose that people regard rnoving exigences as an essential need, and that small increases in the price of transport services do not vary its demand. Therefore an increase in car running cast could not reduce its use, but it could imply the need of saving by means of a reduction in the consumption of other commodities. If bus services are not satisfactory, most people use their own cars. Therefore, in spite of an increase in car running cost, car drivers could use the same amount of road services. Then, if the moving exigences increase, private traffic will increase. This may be true in practice, even if the travel costs have lightly increased.

If car running cost goes beyond the "limit price" of the low income car drivers, some of them switch to public transport, while others reduce the use of their cars (far example they arrange to go together to work, or they ride on a bicycle, and so on). As a consequence of this fact, traffic will easily flow in previously congested areas. Indeed, especially in peak hours, there are less cars in the traffic and it is not difficult to find parking spaces. Therefore less congested roads are time saving, which can be devoted to leisure or to increase the supply of labour, hence to increase income. For several car drivers, time is so precious that they prefer to pay high travel costs for saving time. In their decisions the spur of free running traffic outweighs the price effect, and they can decide to increase the use of their own vehicles. Then, the result of an high raise in car running cost could be the increase of private traffic.

We may explain this result by dif ferentiating the demand equation with respect to car running cost:

the demand for road services is

(a) D = f ( c , k ( c ) )

\vhere the demand (D) is a function of the roads use price (c) and of the degree of congestion (k). Moreover, "k" is a function of "c".

The differential of D with respect to "c" is

(b) (∂ D / ∂ c) = (∂ f / ∂ c) + (∂ f / ∂ k) * (∂ k / ∂ c)

The thesis of this essay is that an high raise in the price of roads use tends to reduce the demand and the degree of congestion; but a lower degree of congestion may increase the demand. Therefore the aggregate demand could increase.

The justification for these assumptions is, first, that are not unreasonable, and secondly the fact that they could explain what has happened in Italy (see the increase in private traffic in Istat, Annuari, 1977-1984).

5 - URBAN TRANSPORT POLICY

Taxes on congestion do not succeed in reducing private traffic, and they tend to result mainly in a financial transfer from car drivers to the Public Authorities.

In order to reduce congestion, it would be necessary to shift the demand curve to the left (see Figure 1). There are at least three policies which should all be implemented:

a) taxes on congestion, to finance the other two measures;

b) to rationalize private traffic;

c) to supply an efficacious and cheaper alternative to the private transport.

Private traffic could be rationalized also by means of the solution of the parking problem. Good ideas may be the "Park-Ride system" and the "filter parking system".

The first system should operate in the suburbs, near public transport stations, and should be free. The second system of parking should be located by the centre of the town, with increasing marginal fare per hour and with absolute higher fares according to the proximity of the parking to the city center (see Aci, Inchiesta sul traffico, 1986, p.24).

Physical restraints on private vehicles should be the extreme measures in dealing with congestion in certain areas.

Public transport is a merit good in that, among other things, its use reduces congestion. The best answer to the moving exigences is the Underground. But, in the short period, an efficacious alternative to the private transport could be bus services, if they are frequent, fast and at low fares, especially in peak hours.

It is often thought that the increase in the number of bus journeys will cause a considerable worsening of congestion (see for example Glaister, 1986, p.229). However an increase in bus frequency would not raise congestion, if it is implemented by a more intensive use of bus reserved lanes.

Bus reserved lanes will, moreover, reduce the room available to private vehicles. Therefore car drivers will face higher costs - in tenn of time employed and fuel consumption - and will have an incentive to use public transport. As pointed out in Section 2, the cost of a journey also includes the opportunity-cost of the time employed. Frequent and fast bus services reduce both waiting time and travelling time.

An intensive use of bus reserved lanes can greatly change the cast of using busses relatively to that of using cars.