Simulating the household plug-in hybrid electric vehicle distribution and its electric distribution network impacts

This paper presents a multi agent-based simulation framework for modeling spatial distribution of plug-in hybrid electric vehicle ownership at local residential level, discovering “plug-in hybrid electric vehicle hot zones” where ownership may quickly increase in the near future, and estimating the impacts of the increasing plug-in hybrid electric vehicle ownership on the local electric distribution network with different charging strategies. We use Knox County, Tennessee as a case study to highlight the simulation results of the agent-based simulation framework.     

Integrating congestion pricing,transit subsidies and mode choice

We model and analyze optimal (welfare maximizing) prices and design of transport services in a bimodal context. Car congestion and transit design are simultaneously introduced and consumers choose based on the full price they perceive. The optimization variables are the congestion toll, the transit fare (and hence the level of subsidies) and transit frequency. We obtain six main results: (i) the optimal car-transit split is generally different from the total cost minimizing one; (ii) optimal congestion and transit price are interdependent and have an optimal frequency attached; (iii) the optimal money price difference together with the optimal frequency yield the optimal modal split; (iv) if this modal split is used in traditional stand-alone formulations – where each mode is priced independently–resulting congestion tolls and transit subsidies and fares are consistent with the optimal money price difference; (v) self-financing of the transport sector is feasible; and (vi) investment in car infrastructure induces an increase in generalized cost for all public transport users.     

Integrating GIS concepts into transportation network data structures

Transportation network data structures must be designed to meet the requirements of the analyses being conducted and must be compatible with the selected graphical user interface. Increasing interest in geographic information systems (GIS) and intelligent transportation systems (ITS) have further burdened the network data structure. It is possible to implement object oriented programming (OOP) technology to satisfy these needs, without making the data structure excessively complicated.

This paper shows how a well‐developed network data structure can incorporate major capabilities normally associated with stand‐alone GIS's. The design of a network data structure derives from both theoretical and practical considerations. A design of a network data structure, composed entirely of objects, is presented. Examples of its implementation, limitations, advantages, and possible extensions are drawn from experience with the General Network Editor (GNE).     

The existence of an equilibrium solution to the traffic assignment problem when there are junction interactions

We consider a network with interactions and capacity constraints at each junction. We give conditions on the interactions and constraints which, if satisfied at each separate junction, ensure that any feasible assignment problem has an equilibrium solution. Two illustrative examples are provided; the first arises naturally and does not satisfy our conditions, while the second does satisfy our conditions but is somewhat unnatural.     

The most likely trip matrix estimated from traffic counts

For a large number of applications conventional methods for estimating an origin destination matrix become too expensive to use. Two models, based on information minimisation and entropy maximisation principles, have been developed by the authors to estimate an O-D matrix from traffic counts. The models assume knowledge of the paths followed by the vehicles over the network. The models then use the traffic counts to estimate the most likely O-D matrix consistent with the link volumes available and any prior information about the trip matrix. Both models can be used to update and improve a previous O-D matrix. An algorithm to find a solution to the model is then described. The models have been tested with artificial data and performed reasonably well. Further research is being carried out to validate the models with real data.     

Aquaculture Parks in the Coastal Zone: A Review of Legal and Policy Issues in the Gulf of Mexico State Waters

The goal of this study is to apply industrial park concepts to the development of aquaculture parks in public waters. The objectives are to identify the permitting process, relevant agencies, and legislation needed to facilitate development. Gulf of Mexico states are surveyed: private parks exist in Florida, but no public parks have developed yet; plans for parks exist in Mississippi, but lack of funding prevents development; no regulations prohibit parks in Alabama, although none currently exist; Texas regulations hinder development of parks; and an experimental park has been proposed in Louisiana, but regulatory gaps have delayed permit issuance.     

On appropriate microstate descriptions in entropy modelling

Using an information-theoretic approach to entropy modelling, expressions for the possible number of microstates are derived from the sets of choices available to households and firms in given location/transport planning situations. In planning applications, the urban space is usually subdivided into discrete zones, and various classes of householders and firms are grouped into separate activities. Nevertheless, the location sites within zones may vary considerably in accessibility, price and quality, and amenity v. cost trade-offs between location and travel many differ markedly between individuals within the same activity group. The inclusion of such variations within a random utility framework is demonstrated to be equivalent to maximizing entropy with the microstates disaggregated to the level where these variations occur. Using constraints based on spatial conditions, observed behaviour and planning policy, entropy maximization is used to determine the most probable macrostate according to each choice set specification. The resulting distributions are compared and their revelance discussed.     

Comparison of inter‐city bi‐modal split models

Using data collected from rail and air passengers on two inter‐city routes in the U.K., seven different model formulations were set up and tested in order to ascertain the most appropriate model format. As a result of the work carried out, it is concluded that a simple Entropy‐type model based on the theoretical work of A. G. Wilson and utilising a linear generalised cost function is the most suitable. Other useful parameters emerging from the work are perceived values of travel time, and a weighting factor for night travel.     

Study on rail corrugation of a metro tangential track with Cologne-egg type fasteners

In Chinese metro lines, rail corrugation on both tangential and tight curved tracks with Cologne-egg type fasteners is very severe. Based on the viewpoint of friction-induced vibration causing rail corrugation, the rail corrugation on a tangential track with Cologne-egg type fasteners is studied in this paper. A vibration model of an elastic multiple-wheelset-track system with Cologne-egg type fasteners is established. Both the complex eigenvalue analysis and the transient dynamic analysis are performed to study the stability and the dynamic performance of the wheelset-track system. The simulation results show that a low rail support stiffness value is responsible for rail corrugation on the tangential track. When the Cologne-egg fasteners characterised by a lower stiffness value are replaced with the DTVI2 fasteners characterised by a higher stiffness value, rail corrugation disappears. However, rail corrugation on tight curved tracks cannot be suppressed using the same replacement. The above conclusions are consistent with the corrugation occurrences in actual metro tracks.     

Book review

Modern Transport Geography. Edited by R. S. Hoyle and R. D. Knowles on behalf of the Transport Geography Study Group of the Institute of British Geographers. (London: Belhaven, 1992.) [Pp.276.] £15–99 (Paperback). ISBN 1 852 93158 2; £45·00 (Hardback). ISBN 1 852 93157 4.