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Transport in saturated soil takes place in that part of soil where pores are completely saturated by water. In the road construction, this usually occurs in the subgrade but rarely in the sub-base. Three principal transport processes are defined: • Diffusion — pollutants move from compartments with higher concentrations to compartments with lower concentrations, even […]

Many physical processes in the pavement, the embankment and the road environ­ment influence the flow of water away from the road surface. Pollution transport is heavily influenced by the physical and chemical characteristics of the specific pollutants. It is also strongly influenced by the interaction between pollutants, and with materials making up the pavement and […]

Road and traffic pollutants are emitted in gaseous, solid or liquid form. Materials used for the construction of pavements and embankments contain pol­lutants mainly in the solid state. However, pollutants initially in the solid state can be released into water. Two processes are at work: • desorption — chemicals are detached from the solids to […]

To some extent, contaminants occurring on the road surface or in the road area have other sources than the traffic or the road. Such sources may be either local or remote. mm/day Fig. 6.2 Estimates of pollution concentrations in snow banks along a highly trafficked city road (AADT 40 000) as a function of the […]

In regions with a cold climate, snow and ice may cover the road surface for a period. Various machinery is used to clear roads of snow. On icy surfaces, sand or grit may be used to increase the friction. For de-icing purposes, road salt is used, mostly NaCl. The salt makes the road wet, thus […]

Road equipment comprises crash barriers, road signs, sign-posts, lamp-posts, etc. Many of these structures are made of galvanized steel. Corrosion of these surfaces releases zinc to the environment (Barbosa & Hvitved-Jacobsen, 1999). Corrosion is promoted under moist conditions often prevailing as a result of splashing from the traf­fic during and after precipitation. Soiling and the […]

Road traffic and cargo produce a range of compounds that pollute the environment. Corrosion of vehicle compartments is a source of heavy metals. Tyre wear gives rise to particles containing zinc, cadmium and iron (literature cited by Fergusson, 1990 [p. 420]; Landner & Lindestrom, 1998; Sarkar, 2002). Brake pads and brake linings emit copper, zinc […]

Pollution sources include five main groups: traffic and cargo, pavement and embank­ment materials, road equipment, maintenance and operation, and external sources. Road and traffic pollutants having received the greatest attention include heavy metals, hydrocarbons, nutrients (mainly nitrogen), particulates and de-icing salt (Table 6.1). Recently, precious metals worn from catalytic converters have also been given attention. […]

Roads and road traffic influence the natural environment in a complex manner. At the same time as roads serve the transport of people and goods, roads take land and form barriers to the movement of people, animals and water in the land­scape. A range of pollutants is emitted from roads and traffic and spread to […]

Lennart Folkeson[12], Torleif Bskken*, Mihael Brencic, Andrew Dawson, Denis Francois, Petra Kunmska, Teresa Leitao, Roman Licbinsky and Martin Vojtesek Abstract This chapter gives an overview of sources, transport pathways and targets of road and traffic contaminants. Pollution sources include traffic and cargo, pave­ment and embankment materials, road equipment, maintenance and operation, and external sources. Heavy […]