Kilometer Of Travel Research Articles

Travel patterns in Dutch metropolitan cities: The importance of external trips

Using a variety of data sources, decentralisation of population and employment in four Dutch urban areas (Amsterdam, Rotterdam, The Hague and Utrecht) over the last 20 years, is analysed. It is found that suburbanisation, plus an ever growing car share, has increased the number of external journeys related to the metropolitan cities enormously. With the use of the 1982 National Travel Survey, current travel patterns in and around the metropolitan cities are studied: the importance of external trips for urban transport planning shows clearly. They account for about half the number of city related car trips, and for nearly three quarters of the total vehicle kilometres of travel within the city.

The epidemiology of fatal motor vehicle accidents in Kuwait

The main objectives of this study are to present data on fatal motor vehicle accidents in Kuwait with a view to find out the principal epidemiological features, establish a baseline for future evaluation, use international death rates to compare Kuwait with other countries and offer specific recommendations as to how the risks involved can be reduced. The epidemiology of all fatal accidents which had occurred in Kuwait between 1 January 1977 and 31 December 1978 are analysed. This two-year series, which includes 726 accidents and represents 1.7% of all types of accidents, resulted in 803 deaths (7.3% of the national deaths toll) and 1175 injuries. The death rates per hundred million vehicle kilometers of travel, per 100,000 registered motor vehicles and per 100,000 resident population in 1978 were about 8.5, 84.8 and 31.7 respectively. These figures reveal significantly higher rates than in some industrialized countries, thus ranking motor vehicle accidents among the four leading causes of death and probably as the commonest single cause of death in Kuwait. The study shows that children under the age of 15 yr contributed 26.2% of all motor vehicle fatalities. 40.9% of pedestrian deaths (55.2% of the series), 25% of pedal-cyclist deaths, 6.3% of motorcyclist deaths and 1.2% of driver deaths. It also confirms the importance of the motor vehicle-pedestrian type of accident (58.3%) and the over-representation of buses, trucks and motorcycles with respect to involvement in fatal accidents as compared to their relative ratios of registered vehicles. The principal recommendations call for the formation of a National Council for Road Safety, the establishment of intensive roadside care, traffic education of road users and at risk groups, improvement of the environment and the firm enforcement of the law to curb the toll of this killer disease in a traditional country undergoing rapid modernization like Kuwait.

Ammonia gas concentrations over the Southern Ocean

Ammonia is the only common, soluble, basic gas in the atmosphere and as such plays an important neutralising, sometimes rate-determining, role in the chemistry of acid gases such as SO2, H2SO4 and HNO3. It also constitutes a reservoir of labile nitrogen in the atmosphere and so must be included in any attempt to describe the cycling of nitrogen through the global environment. We report here values of ammonia concentration measured in Southern Ocean air which are considerably lower than any previously reported1–5. For our analyses ammonia was collected on oxalic acid-impregnated filters and determined colormetrically. In air apparently devoid of contact with land for several thousands of kilometres of travel the mean concentration of ammonia gas was 0.06 μg m−3 (STP). Concentrations in air apparently affected by the Australian continent were several times higher than in the maritime air.

Diffusion in an Ekman Layer

Abstract When a relatively large diffusing cloud is transported by the flow in an Ekman layer, the trajectory and the rate of spread of the cloud are affected by the velocity variations both along and across the geostrophic wind. In a first approximation, these effects may be calculated with the aid of the classical diffusion equation using a constant eddy diffusivity and the classical Ekman layer velocity profile, also derived on the basis of a constant eddy viscosity. Analytical solutions (obtained by the “concentration-moment” method) show that the ground level trajectory of an instantaneously released cloud departs significantly from the surface wind track at distances from the source beyond a few kilometers, and that while this trajectory remains in the sector between surface and geostrophic winds, it does not follow asymptotically either wind direction. The spread of the cloud, as observed at ground level, is dominated, beyond the first few kilometers of travel by the “wind-shear effect” on diffusio...