The convergence of diagonalization algorithms for asymmetric network equilibrium problems

We provide a sufficient condition for the convergence of diagonalization algorithms for equilibrium traffic assignment problems with asymmetric Jacobian matrix B(v) of the link user cost mapping s(v) of the flow v. When

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, where D(v^*) > 0 is the diagonal of B(v^*) and v^* is the equilibrium flow, we demonstrate a local convergence theorem for nonlinear cost functions. The implication of this result for practical applications of the model are outlined.     

On the equivalence of common rearrangements for sum constrained travel estimation problems

This paper examines the problem of estimating the parameters of nonlinear sum constrained models by use of rearrangements to permit linear estimation methods. Over the years a number of different, and sometimes ingenious, techniques have been proposed but a remaining difficulty arises from the fact that different rearrangements lead to different parameter estimates. In this paper it is shown that while ordinary least squares certainly results in different estimates, generalised least squares leads to identical parameter estimates provided convergence to the true maximum likelihood estimates is achieved. In particular it is seen that estimates are invariant with choice of base or deletion of one equation and identical for the single base, multinominal logit, geometric mean and link constant versions. The findings of this paper apply to any sum-constrained model and in transportation these occur very frequently as mode choice problems, singly-constrained gravity models, and as route choice models in path assignment. While we develop all results in this paper in the context of an intercity passenger modal market share model, the transferability of these results to other problems should be recognised.     

The future for in‐vehicle information systems: The technology and its impacts

In‐vehicle information has an important social role to play in improving the efficiency and safety of travel by all modes. In this review, three generations of system are identified. The first generation consists of simple in‐vehicle units relying heavily on external data. The second generation has more sophisticated in‐vehicle units with colour TFT screens and DVD players for maps and entertainment. The third generation again makes use of external data, using the mobile phone network to download map sections and other data as and when required, thereby obviating the need for beacons and map CDs. For locationing, GPS (and/or Galileo, the European version of GPS) remains the favoured technology. Portable devices offering multi‐modal information could improve inter‐modal transport efficiency.     

Hedonic modeling of commercial property values: distance decay from the links and nodes of rail and highway infrastructure

Transportation - This study investigates the impacts of positive and negative externalities of highways and light rail on commercial property values in Phoenix, Arizona. We hypothesize that the...     

Why new technologies cannot radically improve the quality of urban transportation

In recent years a great deal of time and effort has been expended on the development of new modes of transport for cities. It is argued in this paper that this work is unlikely to be very productive because the major remaining flaw in the provision of transportation services—the inability of one mode to provide a good service to concentrated and dispersed trip ends—seems unavoidable. To make the required breakthrough a new mode must be frugal in its demands for space, flexible in its operation and fast. But an analysis of the performance of existing and prototype modes suggest that there is a fundamental technological barrier that precludes any one mode from performing well in more than two out of these three ways. This implies that any further improvements in travel for the urbanite must be made through existing modes and their derivatives and will be quite limited. It also suggests that the only possible way of substantially improving urban transportation is to build or rebuild towns so that one of the important mode attributes mentioned above is rendered superfluous.     

Personal travel management: the adoption and consideration of travel‐related strategies

Traveler behavior plays a role in the effectiveness of travel demand management (TDM) policies. Personal travel management is explored in this paper by analyzing individuals' adoption and consideration of 17 travel‐related alternatives in relation to socio‐demographic, mobility, travel‐related attitude, personality and lifestyle preference variables. The sample comprises 1282 commuters living in urban and suburban neighborhoods of the San Francisco Bay Area. Among the findings: females were more likely to have adopted/considered the more ‘costly’ strategies; those with higher mobility were more likely to have adopted/considered travel‐maintaining as well as travel‐reducing strategies; and those who like travel and want to do more are less likely to consider travel‐reducing strategies. These findings, when combined with those of earlier work on this subject, present a compelling argument for the need to further understand traveler behavior – particularly in response to congestion and TDM policies.     

The optimal dispatching of taxis under congestion: A rolling horizon approach

Taxis make an important contribution to transport in many parts of the world, offering demand‐responsive, door‐to‐door transport. In larger cities, taxis may be hailed on‐street or taken from taxi ranks. Elsewhere, taxis are usually ordered by phone. The objective of a taxi dispatcher is to maximize the efficiency of fleet utilization. While the spatial and temporal distribution of taxi requests has in general a high degree of predictability, real time traffic congestion information can be collected and disseminated to taxis by communication technologies. The efficiency of taxi dispatching may be significantly improved through the anticipation of future requests and traffic conditions. A rolling horizon approach to the optimisation of taxi dispatching is formulated, which takes the stochastic and dynamic nature of the problem into account. Numerical experiments are presented to illustrate the performances of the heuristics, taking the time dependency of travel times and passenger arrivals into account.     

Working at home and elsewhere: daily work location,telework, and travel among United States knowledge workers

Transportation - The mediation of work practices by information and communication technologies enables knowledge workers to telework from remote non-office locations such as their homes, or to work...