Why have traffic fatalities declined in industrialized countries ? Implications for pedestrians and vehicle occupants

This paper examines whether the relationship between traffic fatalities and per capita income is the same for different classes of road users and investigates the factors underlying the decline in fatalities per vehicle kilometer traveled (VKT) observed in high-income countries over recent decades. Formal models of traffic fatalities are developed for vehicle occupants and pedestrians. Reduced-form approximations to these models are estimated using panel data for 32 high-income countries over 1964-2002. The results suggest that the downward-sloping portion of the curve relating traffic fatalities per capita to per capita income is due primarily to improved pedestrian safety. The more detailed models shed light on some factors influencing pedestrian fatalities per VKT, but much of the reduction in pedestrian fatalities remains unexplained. Increased motorization and a reduction in the proportion of young drivers in the population, however, clearly played a role. In contrast to pedestrian fatalities, occupant fatalities do not show a significant decline with income. What does explain declines in occupant fatalities per VKT are reductions in alcohol abuse and improved medical services, and a reduction in young drivers. The importance of demographic factors suggests that in countries where young persons (between 15 and 24 years of age) comprise an increasing share of the driving population, adopting policies to improve young driver education and reduce speeds will be crucial.

Traffic fatalities and economic growth

The authors examine the impact of income growth on the death rate due to traffic fatalities, as well as on fatalities per motor vehicle and on the motorization rate (vehicles/population) using panel data from 1963-99 for 88 countries. Specifically, they estimate fixed effects models for fatalities/population, vehicles/population, and fatalities/vehicles and use these models to project traffic fatalities and the stock of motor vehicles to 2020.The relationship between motor vehicle fatality rate and per capita income at first increases with per capita income, reaches a peak, and then declines. This is because at low income levels the rate of increase in motor vehicles outpaces the decline in fatalities per motor vehicle. At higher income levels, the reverse occurs. The income level at which per capita traffic fatalities peaks is approximately $8,600 in 1985 international dollars. This is within the range of income at which other externalities, such as air and water pollution, have been found to peak. Projections of future traffic fatalities suggest that the global road death toll will grow by approximately 66 percent between 2000 and 2020. This number, however, reflects divergent rates of change in different parts of the world-a decline in fatalities in high-income countries of approximately 28 percent versus an increase in fatalities of almost 92 percent in China and 147 percent in India. The authors also predict that the fatality rate will rise to approximately 2 per 10,000 persons in developing countries by 2020, while it will fall to less than 1 per 10,000 in high-income countries.Economic Theory&Research,Environmental Economics&Policies,Fiscal&Monetary Policy,Roads&Highways,Economic Conditions and Volatility,Inter-Urban Roads and Passenger Transport,Roads&Highways,Economic Theory&Research,Environmental Economics&Policies,Inequality

Making Markets for Development Rights Work: What Determines Demand

Many economists see current land use patterns as inefficient due to various market failures, and planners argue that current patterns do not follow sound planning practice. One policy of interest to both groups is transferable development rights (TDR). TDRs allow the development rights from land that is preserved in an undeveloped state to be transferred to other areas where development can be made denser. This paper addresses one of the greatest difficulties TDR programs face—insufficient demand. We develop a simple theoretical model and estimate a TDR demand function using data from Calvert County, Maryland, one of the only regions where data on individual sales are available. We find that baseline zoning is a critical determinant of TDR demand—demand is high in low-density rural areas but not in the relatively high-density residential areas. We also identify many subdivision characteristics that are significant in explaining TDR use.TDRs, density, zoning, subdivisions

Lot Size, Zoning, and Household Preferences: Impediments to Smart Growth?

The paper explores a number of issues related to lot size and urban density. First, trends in single-family residential lot size over the past 35 years are examined in eight counties in the state of Maryland. We find that there was a trend toward larger lot sizes in many suburban counties in the mid to late 1990s, and that there has been a general flattening of the density gradient in urban areas over the last few decades. We then examine the extent to which lot size is being constrained by regulation by comparing actual subdivision density to the allowable density under zoning rules. This analysis is done for three counties with different degrees of suburbanization. We find that only in the areas with the very large lot zoning does zoning seem to be constraining actual lots size. There is a good deal of excess capacity in the density that could be built, especially in the more densely zoned areas. Finally, recognizing that households have preferences for lot size and other housing characteristics, we provide some evidence about the strength of household preferences over lot size and their willingness to trade off lot size for other characteristics.land use, urban sprawl, density, lot size

Zoning, TDRs, and the Density of Development

Many communities on the urban fringe are implementing a range of policies to preserve farmland and open space, cluster residential development, and guide development to areas with existing infrastructure. These efforts are an attempt to control overall growth and the concomitant loss in open space and also to counter a trend toward the so-called large lot development that often takes place in these areas. Planners have argued that policies to manage density are the most important local policy focus for urban areas in the coming years. It is possible that large lot development and sprawl are themselves the result of government policy. Most local governments use zoning to establish minimum acreage requirements for each residential dwelling unit; in ex-urban localities, these limits are often quite high. Developers might build a subdivision with average lot sizes greater than the minimum but they cannot by law go below it. Some researchers have argued, however, that the spatial patterns of development are simply the natural result of household preferences and market forces. In this paper, we address the question of whether zoning limits are the primary cause of lowdensity, sprawling development or whether market forces tend to dictate this outcome. If zoning limits account for low-density development in at least some cases, how would development patterns be different if there had been no such rules? We begin by constructing a simple model of the developer decision about the density of new development. The subdivision is the unit of observation, and developers must weigh both demand and cost considerations in choosing density, in addition to complying with zoning restrictions that vary across parcels. We apply the model using parcel-level data from a region where zoning rules vary but are exogenous to the period under study. Calvert County, Maryland, near Washington, DC, is an historically rural county that has experienced rapid growth in recent years. The county has a transferable development rights (TDRs) program that has led to a great deal of variability in the intensity of development across properties. We are able to not only examine the extent to which zoning has contributed to large lot development but also to determine the economic forces that underlie density decisions. Finally, we are able to forecast how density would have been different in the absence of zoning rules by estimating a Tobit equation that is censored for the observations constrained by zoning.housing density, zoning, transferable development rights

The Trade-off between Private Lots and Public Open Space in Subdivisions at the Urban-Rural Fringe

In many communities on the urban–rural fringe, subdivisions are subject to “clustering” rules, in which houses must be located on a portion of the total land area and the remainder of the land is left as open space. This open space may be undisturbed forest or pastureland, or it may include recreation facilities and trails. In some communities, the open space may remain in agricultural use as pasture or cropland. Although the open space may provide benefits to subdivision residents, it means that those residents are living in a higher-density setting than people living in conventional subdivisions. It is unclear whether the benefits offset the loss experienced by smaller lots and higher density. This trade-off is the focus of our study. We use data on subdivision house sales occurring between 1981 and 2001 in a county on the fringe of the Washington, DC, metropolitan area to estimate a hedonic price model. We examine how households value being adjacent to open space and having more open space in the subdivision, and how they may be willing to trade off those amenities with their own private lot space. We find that private acreage matters to households—a 10 percent larger lot leads to about a 0.6 percent higher house price, all else being equal. Subdivision open space is also valuable to households, but the marginal effect is much smaller than the marginal effect of private lot space. We also find that subdivision open space does substitute for private land, but the extent of the trade-off is small. We use the results of the estimated hedonic model to simulate the effects on prices of jointly increasing open space and reducing average lot size, holding the size of the subdivision constant. We find that average house prices are lower with clustering, particularly for interior lots that are not adjacent to open space.subdivisions, clustering, hedonic property values, open space

Estimating the Social Cost of Carbon for Use in U.S. Federal Rulemakings: A Summary and interpretation

The United States Government recently concluded a year-long process to develop a range of values representing the monetized damages associated with an incremental increase in carbon dioxide (CO2) emissions, commonly referred to as the social cost of carbon (SCC). These values are currently used in benefit-cost analyses to assess potential federal regulations. For 2010, the central value of the SCC is $21 per ton of CO2 emissions and sensitivity analyses are to be conducted at$5, $35, and$65 (2007$). This paper summarizes the methodology and process used to develop the SCC values, complemented with our own commentary about how the SCC can be used to inform regulatory decisions and areas where further research would be particularly useful

Why Have Traffic Fatalities Declined in Industrialized Countries' Implications for Pedestrians and Vehicle Occupants

Previous research suggests that the death rate due to traffic fatalities at first increases as countries develop and motorization increases, but eventually declines as incomes grow and fatalities per vehicle decrease (Kopits and Cropper, 2005). This paper examines whether the relationship between traffic fatalities and income is the same for different classes of road users and investigates the factors underlying the decline in fatalities per vehicle kilometer traveled (VKT) observed in high-income countries over recent decades. Formal models of traffic fatalities are developed for vehicle occupants and pedestrians. Reduced-form approximations to these models are estimated using panel data for 32 high-income countries over 1964-2002. The results suggest that the downward-sloping portion of the curve relating traffic fatalities per capita to per capita income is due primarily to improved pedestrian safety. Our more detailed models shed light on some factors influencing pedestrian fatalities per VKT but much of the reduction in pedestrian fatalities remains unexplained; however, increased motorization and a reduction in the proportion of young drivers in the population clearly played a role. Occupant fatalities, however, do not show a significant decline with income. What does explain declines in occupant fatalities per distance traveled are reductions in alcohol abuse and improved medical services, and a reduction in young drivers. The importance of demographic factors suggests that in countries where young persons (between 15 and 24 years of age) comprise an increasing share of the driving population, adopting policies to improve young driver education and reduce speeds will be crucial.

Estimating the Social Cost of Carbon for Use in U.S. Federal Rulemakings: A Summary and Interpretation

The United States Government recently concluded a year-long process to develop a range of values representing the monetized damages associated with an incremental increase in carbon dioxide (CO2) emissions, commonly referred to as the social cost of carbon (SCC). These values are currently used in benefit-cost analyses to assess potential federal regulations. For 2010, the central value of the SCC is $21 per ton of CO2 emissions and sensitivity analyses are to be conducted at$5, $35, and$65 (2007$). This paper summarizes the methodology and process used to develop the SCC values, complemented with our own commentary about how the SCC can be used to inform regulatory decisions and areas where further research would be particularly useful.

Traffic Fatalities and Economic Growth

This dissertation adds to the current understanding of the socioeconomic determinants of traffic fatality rates by examining the variation in road deaths across countries and over time. Chapter two investigates the relationship between road safety and economic development within an Environmental Kuznets Curve framework. Reduced-form models of fatality risk as a function of per capita income are estimated using panel data for over 80 countries. The results confirm an inverted U-shaped relationship with income, with traffic fatality risk (fatalities per population) beginning to decline at incomes similar to those found for several environmental externalities. The turning point is driven by the rate of decline in fatalities per vehicle as income rises, since motorization rates (vehicles per population), while increasing with income at a decreasing rate, never decline with economic growth. This suggests that road safety improvements accompanying income growth depend on policies that reduce fatalities per vehicle rather than on reducing motorization. Projections suggest that the global road death toll will grow by 66% between 2000 and 2020 if historic trends continue. This number, however, reflects divergent rates of change in different parts of the world. Chapter three focuses on factors underlying the decline in fatalities per distance traveled, i.e., the downward sloping part of the road safety Kuznets curve. Formal models of traffic fatalities are developed for vehicle occupants and pedestrians. Reduced-form approximations to these models are estimated using panel data for over 30 high-income countries over 1964-2002. Estimates suggest that demographic changes and road building contributed to declines in both vehicle occupant and non-occupant fatality rates. In addition, increases in the size of the vehicle fleet, as predicted by theory, have increased occupant deaths while decreasing pedestrian deaths per distance driven. Improvements in medical care also played a role in reducing both fatality rates. The results do not offer evidence of a significant increase in demand for risky driving in response to newer, safer vehicles or seatbelt usage. The extent to which alcohol and increases in the elderly population have detrimental effects on fatality rates is found to be twice as large for pedestrians as for vehicle occupants