[sustran] Re:traffic crashes more important than air pollution

[Christopher Zegras]

While recognizing the imperfections of "costing" transport impacts, these do
offer a way to compare and possibly rank urban transport hazards such as
accidents and pollution.  

For example, we have recently completed a transport cost assessment in
Santiago de Chile, 
including analysis of accident costs and pollution costs.  Here, I think it
is important to consider the "External" portion of accident costs, since
these are those comparable to air pollution.  Based on our estimates
external accident costs in Santiago in 1994 amounted to about US$194
million, while external air pollution costs amounted to about US$535 million
(161 million due to direct tailpipe, 350 million due to road dust).  It is
important to note that both of these estimates are likely underestimates
(our assumptions and methodologies are briefly described below).  Still,
these estimates would suggest that air pollution is a more dire public
health issue in Santiago.  Of course, this will not be the case in all
cities, since some cities won't have the same meteorological and
topographical conditions as SAntiago (which are conducive to high pollution
concentrations), and others may have more or less safe transport systems.  

Our analysis does lead to one conclusion similar to that of Sr.
Vasconcellos' paper, that relating to the issue of equity.  For example,
both pedestrians and cyclists suffer relatively high accident cost rates,
indicating a traffic system that discriminates against these relatively
benign modes.  Without motorized traffic, the accident costs for these two
modes would be considerably less: pedestrian trips on their own incur no
costs, bicycle trips on their own incur some accident costs, a combined
bicycle-pedestrian system produces inter-modal collisions (an estimated 80
bicycle-pedestrian accidents in Santiago, about 1.7% percent of all
pedestrian-vehicle conflicts).

The high accident costs for both of these non-motorized transport (NMT)
modes represents an externality within the accident “market,” these modes
suffer higher costs due to the presence of motorized modes.  The presence of
this externality suggests that motorized modes should pay for the
development of traffic management measures which reduces NMT-motorized
transport conflicts.  Such measures could include “traffic calming” programs
which have been shown to produce reductions in both the frequency and cost
of traffic accidents (Zein, et. al 1997).  Not only would such investments
reduce the risks and costs associated with NMT travel, but it would also
likely increase the use of these modes.  For example at least one study has
shown that an increase in the safety conditions for cyclists produces a more
than proportional increase in bicycle use (Noland 1995).

Accident Assumptions
Our accident costs are derived from data (on number of incidents, gravity of
injuries, number of deaths, number and type of vehicle involved) provided
directly by the Comisión Inter-Ministerial para la Seguridad del Tránsito
for the 34 Comunas of Greater Santiago and disaggregated -- for each
incident-- according to type of accident (i.e., single vehicle collision),
number of vehicles damaged, number and gravity of injuries, and number of
vehicles involved by vehicle type (17 different vehicle types were
considered). Accident cost estimates come from the same Comisión and were
developed by the local consulting firm CITRA.   CITRA provides average
external and internal costs, based on the human capital approach, per
accident type and injury type.   

Based on this data and cost figures, we developed cost estimates per vehicle
type using a calculation which attributes the public and private costs of
injuries and/or deaths and the public and private costs of vehicles damaged
to each vehicle involved in a given accident. Our estimates do not attribute
costs according to fault; instead costs are attributed evenly across
participating vehicle types in each particular incident. For example, for a
collision involving a bus, a taxi, and an automobile, with one death, one
medium injury, and two vehicles damaged we attribute the sum of the costs of
the death, the injury, and vehicles.

Based on this method, in 1994, traffic accidents in Greater Santiago costed
about US$351 million (194 external and 156 internal).  Our "external" cost
estimates here include loss of daily productivity due to injury,
administrative costs (police, courts, etc.), and human resource allocation
for rehabilitation, administration, etc, and the loss of future productivity
due to premature death.  These estimates are likely underestimates since
they are based on the Human Capital approach, not the willingness to pay
approach, which can generate cost estimates an order of magnitude higher
than the human capital approach.

Tailpipe Air Pollution
Tailpipe air pollution estimates are generated based on average fleet
emissions factors (in grams per kilometer) for the various transport modes
in the city multiplied by the estimated cost per gram of pollutant for
PM-10, CO, VOC and NOx, and ozone (estimating equal contribution of VOC and
NOx to ozone formation.  The cost per gram of pollutant comes from the cost
estimates developed in World Bank study, updated to average wage rates in
Santiago for 1994.  

These costs are likely underestimates, since they are based only on the
human capital costs for human morbidity and mortality, not on comprehensive
cost values derived from willingness to pay, which typically produces higher
cost estimates. In addition, these estimates omit SOx and lead costs,
additional particulate costs from break and tire wear, and ignore the
potentially significant costs of crop damage, building damage and cleaning
costs, and aesthetic costs (i.e., loss of view of the Andes and potential
lost tourism revenues). These cost estimates also do not include long-term
health effects due to exposure to pollution (i.e., cancer and other
effects).  Finally, these costs do not include the potential costs of
climate change due to emissions of CO2 and other greenhouse gases. 

Road Dust Emissions
Road dust emissions costs are based on Santiago's 1994 emissions inventory
of respirable particulates, 70% of which are attributable to road dust
kicked up from paved and unpaved streets.  These dust particulates are
attributed the same economic cost as that for tailpipe emissions of PM-10,
as developed in the World Bank study.

>
>------------------------------
>
>Date: Tue, 17 Jun 1997 14:18:46 +0800
>From: barter at central.murdoch.edu.au (Paul Barter)
>Subject: [sustran] traffic crashes more important than air  pollution
>
>I have just come across a paper which makes the argument that "developing
>countries need safer streets more than cleaner cars and that a change in
>current priorities is therefore required."
>
>The paper, by Eduardo A. Vasconcellos of the University of Sao Paulo,
>Brazil, is entitled" Transport and Environment in Developing Countries:
>Comparing Air Pollution and Traffic Accidents as Policy Priorities. in
>Habitat International, Vol. 21, No. 1, pp. 79-89, 1997.
>
>Here are a few quotes from the conclusion,
>"Although air pollution is increasingly identified as a priority target for
>transport policies in developing countries, it is not the most important
>environment-related transport problem in this part of the world. Traffic
>accidents must be considered more important in view of the numbers killed
>or injured, the mostly one-sided nature of this violence, and the
>collective nature of the phenomenon.
>.....
>Accidents..already account for more injuries than common diseases and rank
>among the leading causes of violent deaths.  Unlike air pollution, which is
>spatially concentrated, the problem of traffic accidents is collective and
>affects both small and large towns, and urban and rural areas alike.
>.....
>The social dimension of the problem is highlighted by an analysis showing
>who is most affected. Pedestrians, the most vulnerable of the roles played
>in traffic, and the most harmed, account for a high percentage of total
>fatalities (60% in a large city such as Sao Paulo).
>.....
>This does not mean that air pollution control should be abandoned, but
>rather that the various objectives should be appropriately rank-ordered in
>terms of priority...."
>
>
>I have only glanced through it but the paper seems to be critical of
>efforts to get traffic moving faster, which are often justified partly by
>claims that this will lower air pollution. Besides not actually decreasing
>air pollution in the long term, such measures add to the level of danger of
>the street environment for vulnerable road users.
>
>It is an interesting and provocative argument. I don't have time to assess
>it in detail.. does anyone else have any views or evidence on this?
>
>Best wishes,
>
>A. Rahman Paul Barter
>Sustainable Transport Action Network for Asia & the Pacific (SUSTRAN)
>Until 15 July I am in Perth, Australia.
>During that time please reach me at <barter at central.murdoch.edu.au>
>
>------------------------------
>
>End of sustran-discuss V1 #17
>*****************************
>
>
 Christopher Zegras       http://www.iiec.org                 /\   /^\
 Instituto Internacional para la Conservacion de Energia /^\ /_o\ /   \
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