Traffic, its impacts and public attitudes - Transport Policy and Planning in Great Britain - page 41

3 Traffic, its impacts and public attitudes

3.1 Introduction
In the previous chapter we considered social and economic trends and their outcome
as reflected in people's travel. In this chapter we look at trends in the volume and
composition of traffic - that is in vehicle movement arising from the use of mechanised
transport - and its impacts. As well as movements associated with personal travel there
are those deriving from commercial journeys (in light vans) and from the conveyance
of freight.
Strictly the term 'traffic' embraces all mechanised modes and, when we come to
look at air pollution for example, their overall impact will be reported. However, in
many contexts we will be confining attention to road-based modes, i.e. to the way the
term is used in common parlance. In this chapter therefore, unless otherwise stated,
'traffic' refers to road traffic. Even here it is sometimes necessary to distinguish between
mechanised and motorised traffic (the latter excluding cycling).
As a manifestation of motorised mobility traffic can be considered to have positive
and negative impacts. Many of these have been referred to in the first two chapters.
Ironically the attractions of greater mobility can rebound upon travellers themselves as
people find their journeys taking longer, and becoming more unreliable and unpleasant
through increasing congestion and overcrowding.
In this chapter however we focus on the impacts of motorised traffic and its
associated road infrastructure upon people other than those making the journeys
concerned. These impacts centre principally upon road safety and the environment.
In a direct sense they are wholly negative in character although individual highway
and traffic management schemes, whilst typically having negative impacts themselves,
are often designed to bring about safety and environmental improvements elsewhere.
We begin by describing trends in the volume and composition of traffic and its
distribution amongst different elements of the highway network (3.2). This is a
relatively straightforward matter as comprehensive statistics have been maintained for
several decades. The same is true (courtesy of police records) of traffic accidents and
the casualties arising (3.3). Other forms of impact however are much more difficult to
report on. This is partly because of the absence of comprehensive monitoring which
in turn can be linked to difficulties in measurement and the costs of data collection.
The sense of danger experienced by people using the transport system is a case in
point. There is no automatic correlation between measured objective conditions (the
probability of being involved in an accident) and individuals' perceptions of danger.
Some attitudinal data generated nationally can nevertheless provide insights into the