9.2.8.4 Co-benefits from Reduced Road Traffic

Nations may choose to include GHG mitigation along with improvements in urban air quality and other traffic-related damages as objectives for policies designed specifically to reduce road traffic. The policies have co-benefits in terms of:

• reduced air emissions associated with less fuel use (e.g., Ross, 1999), and therefore consequent reductions in the damages caused by these emissions;
• reduced congestion;
• fewer traffic crashes;
• less noise; and
• less road damage.

The co-benefits from less noise and road damage are only likely to be large for substantial levels of mitigation (see ECMT, 1998 for valuations of these benefits for some European countries).

9.2.8.4.1 Air Pollution Associated with Road Traffic

There are likely to be substantial GHG co-benefits from some policies mainly aimed at reducing air pollution; these are mostly considered in Chapter 8.

Today 3 out of 4 of the world’s highly dense megacities are in the rapidly developing countries, where traffic congestion is often high, involving highly polluting and inefficient vehicle fleets (WRR, 1998). Because of this, reducing traffic and congestion will also lower potential exposures to known hazards from the burning of road fuels, especially to those living near to congested roadways. Children are at high risk from the damaging neurological effects of pollution. A recent report from the WHO and the European Environment Agency estimates that 21,000 deaths annually are tied with air pollution from traffic in Central Europe (WHO, 1999).

The total of health damage costs from road traffic is significant. A recent study jointly produced by agencies of the Swiss, French and Austrian ministries of health, environment, and economy estimates that the annual number of deaths linked to traffic based pollution in these countries exceeds those that occur because of traffic crashes alone. This study uses a willingness-to-pay approach to economically evaluate traffic-related air pollution health effects. In all three countries, the total air pollution related health costs are US$49.7bn⁹, with $26.7bn coming from road traffic-related pollution. As a percentage of GDP, such costs in these countries range from 1.1%-5.8% (Sommer et al., 1999). A recent study from Sao Paulo (Miraglia et al., forthcoming), estimated that by 2020, 35300 avoidable deaths from air pollution will occur if current trends in transportation continue and about 150,000 children will be admitted to the hospital or visit the emergency room.

9.2.8.4.2 Road Congestion

The research done on the ancillary benefits of GHG mitigation policies on road transport suggests that the value of the consequent reduction in congestion may be one of the most significant of such benefits (Barker et al., 1993). Traffic congestion also contributes to increased exposure to pollutants by passengers during periods of congestion, with levels inside private vehicles found to be 2 to 8 times those in the surrounding air (Fernandez-Bremauntz and Ashmore, 1995). Action to reduce this congestion can be expected to lower risks associated with such exposures, as well as lessen public health impacts of associated pollutants more generally.

9.2.8.4.3 Road Traffic Crashes

Section 9.2.8.2 lists several options for transport policies to mitigate GHGs. Some of these options, such as expanded reliance on mass transit and shifts away from individual passenger vehicles, can be expected to decrease the number of traffic crashes. The total number of damages resulting from crashes is substantial. With respect to traffic deaths and disabilities, the World Bank reports that traffic crashes are already the leading cause of death for young males and the 5th leading cause of death for young females worldwide. About 75% of all deaths occur in developing countries, although they have less than 1/4 of all vehicles. If present trends continue to 2020, one fourth of all health costs in developing countries may be spent on treating road injuries alone (Ross, 1999). However, policies that encourage the use of smaller vehicles could have increased death and injuries caused by traffic crashes (Dowlatabadi et al., 1996).

The extent to which these total damages may be affected by various climate policies remains unknown, but is likely to be nontrivial and to vary in developed and developing countries. For instance, shifting travel from personal vehicles to mass transportation for large populations in the megacities of Sao Paulo and Shanghai (MacKenzie, 1997) has been projected to yield two sets of ancillary benefits:

1. less net GHG emissions from transport, and
2. lower incidence of traffic-accident-related morbidity and mortality.
   

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