Driving by choice or necessity?

From just about all accounts, Americans are driving more than ever, not just to work but to shopping, to school, to soccer practice and band practice, to visit family and friends, and so on. Americans also seem to be complaining more than ever about how much they drive—or, more accurately, how much everyone else drives. However, the available evidence suggests that a notable share of their driving is by choice rather than necessity. Although the distinction between choice and necessity is not always so clear, it is important for policy makers. For necessary trips, planners can explore ways of reducing the need for or length of the trip or ways of enhancing alternatives to driving. For travel by choice, the policy implications are much trickier and touch on basic concepts of freedom of choice. This paper first develops a framework for exploring the boundary between choice and necessity based on a categorization of potential reasons for and sources of “excess driving”, and then uses in-depth one-on-one interviews guided by this framework to characterize patterns of excess driving. This research contributes to a deeper understanding of travel behavior and provides a basis for developing policy proposals directed at reducing the growth in driving.     

Driving Forces behind the Growth of Per‐capita Car Driving Distance in the UK, 1970–2000

Abstract

Although per‐capita car trip distance (measured in passenger‐km) and car driving distance (measured in vehicle‐km) in the UK have kept increasing, their growth rates slowed considerably in the 1990s when compared with the 1970s and 1980s. The paper investigates the main driving forces behind the changes in car trip and car driving distances, and it examines the determining factors for the slow down of growth in the 1990s on the basis of the analysis of data from the National Travel Survey (1975/76, 1989/91, 1992/94, 1995/97 and 1999/2001). In particular, it emphasizes the significance of changes in car ownership levels as a key driving force and attempts to separate this ‘car ownership effect’ from other effects. The log‐mean Divisia index decomposition method is applied to measure the relative contribution of each effect. Separate analyses are undertaken according to trip purpose. Other underlying causes, such as changes in fuel price and road capacity, are also examined.     

High- Speed railway lines in Germany:Experience in Tunnelling in Karstic Geology and Discussion Of Tunnel Driving Methods

In the course of Deutsche Bahn's new high - speed railway line between Nuremberg and Ingolstadt, a number of tunnels are being constructed, with a total length of about 15 km. One of the longest tunnel is the 7,250 m long Irlahüll tunnel.The tunnel was driven in karst geology. It was not expected that karst phenomena would be so widespread. This forced client, designer and contractor to take a new approach to the project. Different tools were developed to handle the problems on site. Additional site investigations had to be performed to identify karst phenomena in the vicinity of the tunnel. For validating the stability and serviceability of the tunnel, a new way of defining the probability of failure of the construction had to be found. Based on the experience of the tunnel driving at the high - speed railway line in Germany between Nuremberg and Ingolstadt, two different methods of tunnelling are discussed: Drill and blast ( New Austrian Tunnelling Method: NATM) and the use of tunnel boring machines (TBM).