Urban Transport Strategy. Management in Developing Countries John A Cracknell, страница 68

7.8.1.   Traffic management schemes within World Bank projects are generally evaluated by the

application of conventional transport planning evaluation procedures.  The World Bank places great emphasis on economic evaluation and thus in general, requires benefits of transport investments to be expressed in monetary terms.  The main quantifiable benefits arising from a component usually include

♦            Savings in travel time (and thus travel cost) for people using the transport system;

♦       Savings in vehicle operating costs; and ♦           Savings in accident costs.

7.8.2.      It is not within the scope of the Review to discuss in detail the procedures for assessing these savings nor the approach to the determination of input parameters which have proved contentious in the past (such as the value of person time in working time, value

of person time in non-working or commuting time etc).  However the following important points are noted:

a)  Conventional economic analysis of traffic schemes usually gives very high economic rates of return (EIRR) where those schemes improve bus and traffic speeds as (i) schemes are often relatively low in cost and (ii) time savings usually apply to many vehicles (both public and private) and travellers;

b)  Provided person time savings of all transport system users affected by a scheme are included in the analysis (and there have been cases in the past where the World Bank has been reluctant to include person time savings), a quantified economic evaluation includes, ipso facto, some poverty impact (as most travellers use public transport users in developing cities have lower incomes than car users);

c)  Conventional economic evaluations do not include benefits for pedestrian schemes (there are exceptions for pedestrian schemes such as accidents - see below) or bicycle schemes.  There are no standard procedures for the economic evaluation of these measures and thus the poor, who are likely to make use of such measures, may suffer.  It is sometimes the case that pedestrian measurers are "carried" by the benefits to traffic and buses; for example, complete rehabilitation of the footways has been included in a bus priority scheme in the proposed Mumbai UTP although no pedestrian travel time benefits have been included.  However, such an approach does not deal with the pedestrian or bicycle measures which are proposed as "stand alone" schemes;

d)  Environmental impacts are rarely assessed in quantified terms in the economic evaluation of traffic management schemes.  To a large extent, this is due to lack of analytical tools (or time and resources) for application to traffic management schemes.  Some traffic planning programs (such as the traffic signals assessment program TRANSYT) provide, as an output, fuel consumption savings as a proxy, for environmental impacts;

e)  Some pedestrian schemes are assessed in quantified terms:

♦            accident impacts are conventionally included in quantified economic evaluations but it must be recognized that (i) the base data is likely to incomplete (see Chapter 6) and (ii) "with" scheme assessments of accident reductions is extremely problematic;

♦            some pedestrian road crossing facilities are assessed in quantified terms by the assessing the benefits of reduced delay to traffic flow.  While there are undoubtedly benefits, the danger is that pedestrians are subjugated to vehicle needs and the schemes may inconvenience pedestrians while still providing vehicle benefits.

7.8.3.      It is considered that quantified economic evaluation or "cost-benefit" analysis is an incomplete analytical base for traffic management schemes.  A complete evaluation should address, as well as economic return, policy impacts, environmental impacts, poverty impacts, quality impacts etc and should not rely solely on evaluations expressed in monetary terms.