Urban Transport Strategy. Management in Developing Countries John A Cracknell, страница 24

3.1         Introduction

3.1.1.      The Terms of Reference require the Review to consider the experience of the Bank, and as far as possible, of other international funding agencies, in traffic management components with a view to assessing the “lessons learned” in terms of design problems, impacts and sustainability.  The Terms of Reference identify traffic management components in terms of junction channelisation, bus priority, marking, signing and similar.  Drawing general “lessons” from interventions poses difficulties for the following reasons:

a)  Specific nature of traffic management – as explained in Chapter 1, traffic management is highly city-specific and depends on level of city size, development, levels of traffic congestion, traffic characteristics and thus measures which are successful in one city may not be appropriate or successful in another;

b)  “Area wide” application - traffic management can be applied at a specific site; for example, improvements may be necessary at a key junction to ensure consistent traffic capacity along a route or improvements may be made at a junction to resolve a severe accident problem.  However, traffic management is most effective if applied over an area (say, a corridor or a local area or a town centre or the whole city) to develop a consistent traffic management regime to ensure that:

♦            the objectives of an overall traffic strategy are realised;

♦           traffic problems are not simply transferred to new conflict points;

♦           there is synergy between the various interventions; and

♦            users are presented with the same “messages” thereby improving the likelihood of observance of traffic regulations

c)  “Stand alone” measures – generally, traffic management interventions should not be regarded as “stand alone” measures.  Traffic management should seek to balance often conflicting objectives and thus needs to combine individual interventions (in traffic, public transport, pedestrian schemes and NMT) to form effective,

“comprehensive packages”; for example,

♦            the introduction of a new traffic signals system is most likely to require junction modifications to ensure that the full potential of the new signals is realised; or

♦            a bus lane scheme will require simultaneous improvements to junctions, traffic regulation enforcement, parking controls; or

♦ junction improvements to increase traffic flows and speeds must include measures for pedestrians and/or NMT.

d)  Regulatory measures - traffic management will not usually comprise physical interventions alone; physical works must generally be supported by regulatory actions (such as enforcement or traffic laws) to ensure that the measures function as planned; and

e)  Policy measures – physical interventions are only the means of achieving a defined traffic management policy; “lessons learned” from individual interventions cannot be separated from the policy they support.  A policy is required which enables "measures of effectiveness" sought from each intervention to be defined.

f)  Road hierarchy context - the starting point for the development of traffic management measures is the definition of a traffic policy which sets the objectives for meeting the differing needs of road users (traffic, public transport, pedestrians, cyclists, other non motorised vehicles, commercial vehicles, etc) and differing transport functions (through travel, business access, residential access, servicing, parking, etc).  The road network should be categorised so that mutually incompatible functions are, as far as practicable, separated onto different roads and thus a "functional road hierarchy" is defined.  The development of traffic management measures themselves must then be planned in the context of the road hierarchy; for example, while intensive bus priority is likely on major arteries, it may not be appropriate on local access roads even though they may be used by buses.