5.- Elasticity in price and time of the function of demand for private transport.
The coefficients that have been got with the models for the different explicative variables,
say to us the relative importance of each one of them about the choice between urban and
private transport for the displacement to work, but what is really useful to establish a politic
of transport that will guarantee an optimal modal distribution, is the knowledge of
elasticities. These offer information about the effects aggregated of variations in the
attributes being able to foretell then the impacts what changes in velocity, the frequency
and in the prices have about the modal distribution, for this reason, they are a proper
instrument to design the global offer of urban transport or to establish punctual changes in
the existent one.
The elasticities have been calculated for discrete changes between 10% and 50% as in the
variable price as time and in the three samples, the results obtained have been similars in
both cases and are gathered in Chart 4.
The obtained elasticities are similar in the 2 non-restricted samples, with exception of the
crossed elasticities of urban transport according to the price of private transport that is
sensibly superior in the largest sample, this similarity is because the difference in both
samples are in the cause that the most reduced includes an only travel per person and then
the caracteristics of the model must not be very different.
In general the elasticities according to the price are superior than according to the time,
although it does not happen in the restricted sample in the case of urban transport, where
the elasticity of price in this way of transport is similar to the time one. In this sample we
can emphasize the high values that the urban transport elasticity have got, and this makes us
think that a proper reestructuration of lines and an efficient politic of prices in this way of
transport could help to a modal distribution more balanced than the actual. The elasticities
in the same sample, but according to private transport is more rigid and consistent with the
results of other studies made with similar methodologies (Matas, 1990) except with the
elasticity, price of private transport that is superior to the unity what means a high
sensibility of users of private transport according to the costs of this way, for this reason, it
could de effective to introduce a politic of urban toll to reduce the congestion, although the