National policy towards cars: Greece

Passenger car ownership and use in Greece has been a matter of serious consideration at government level, only in the last decade with the increasing traffic congestion in the big cities. However, government policy towards private car ownership has always been influenced by two main factors.

First, that virtually all vehicles have to be imported, a fact which has a serious balance of payments implication for a small country like Greece.

Second, the traditional heavy taxation of motor vehicles and fuel, brings high revenues for the national budget. Recently a third consideration has been added, that of energy consumption and of the environmental effects of car use.

From the point of view of car owners, ownership was originally seen as a means of social recognition and establishment, but for the last decade it has been considered mainly as an everyday necessity more or less imposed on one, by a number of other well accepted facts of everyday social and professional life.

Influenced by the two main factors above; private car ownership and use in Greece has developed for the last two decades at a pace similar to but not the same as in other Western Countries. In this paper the existing situation and prospects will be examined and comments made on the peculiarities characterizing the Greek scene.     

Factors Influencing Behavior in a Boating Speed Zone

The greatest source of human-related mortality for endangered Florida manatees is collisions with watercraft. Regulation of boat speeds is the principal management tool to minimize this threat. Demands on law enforcement limit their ability to monitor boater behavior and managers seek alternative strategies to increase compliance. The purposes of this study were to: (1) explore the effectiveness of an on-site sign to enhance boater compliance in a boating speed zone, and (2) examine the environmental and boating characteristics that influence the probability of compliance. Signs designed to increase compliance were posted halfway through the 18-week study period. The signs were not related to compliance level. Logistic regression models showed that only time of day and boat type were significantly related to compliance. Results suggest that passive methods of persuasion may not be an effective means of influencing boater behavior.     

Diesel-engined vehicle nitric oxide and soot emissions during the European light-duty driving cycle using a transient mapping approach

An engine mapping-based methodology is developed to gain a first approximation of a vehicle’s performance and emissions during a light-duty cycle. The procedure is based on a steady-state experimental investigation of the engine with an appropriate vehicle drivetrain model applied so that the cycle vehicle speed data can be transformed into engine speed and torque. Correction analysis is then applied based on transient experimentation to account for the transient discrepancies during real driving. The developed algorithm is applied for the case of a diesel-engined vehicle running on the European light-duty cycle. A comparative analysis is performed for each section of the cycle revealing its individual transient characteristics.     

Book reviews

THE SEVENTH AUSTRALIAN TRANSPORT RESEARCH FORUM, by K. W. Ogden.

AIRLINE PLANNING: CORPORATE, FINANCIAL AND MARKETING by Nawal K. Taneja. Lexington, Mass., Lexington Books, 1982. 207 pp. (£19.50)

SOLVING LOCAL GOVERNMENT PROBLEMS: PRACTICAL APPLICATIONS OF OPERATIONS RESEARCH IN CITIES AND REGIONS, by Charles E. Pinkus and Anne Dixson. George Allen and Unwin, London, 1981. (Hardback £20.00; paperback £8.95)

SCIENTIFIC MANAGEMENT OF TRANSPORT SYSTEMS, edited by N. K. Jaismal. Published by North‐Holland Publishing Company (U.S. $58.50)

TRANSPORTATION AND TRAFFIC ENGINEERING HANDBOOK (Second Edition), edited by W. S. Homburger, Englewood Cliffs, N.J., 1982. Prentice Hall, pp. 883.

ECONOMICS OF PUBLIC TRANSPORT, by C. A. Nash. Longman, London, pp. 194. (£6.95).     

Effects of household structure and selected travel characteristics on trip chaining

This paper analyzes trip chaining, focusing on how households organize non-work travel. A trip chaining typology is developed using household survey data from Portland, Oregon. Households are organized according to demographic structure, allowing analysis of trip chaining differences among household types. A logit model of the propensity to link non-work trips to the work commute is estimated. A more general model of household allocation of non-work travel among three alternative chain types — work commutes, multi-stop non-work journeys, and unlinked trips — is also developed and estimated. Empirical results indicate that the likelihood of linking work and non-work travel, and the more general organization of non-work travel, varies with respect to household structure and other factors which previous studies have found to be important. The effects of two congestion indicators on trip chaining were mixed: workers who commuted in peak periods were found to have lower propensity to form work/non-work chains, while a more general congestion indicator had no effect on the allocation of non-work trips among alternative chains.     

The role of anticipated time pressure in activity scheduling

In the present article we focus on the cost or disutility of engaging in activities arising from the time pressure people frequently experience when they have committed themselves to perform too many activities in a limited amount of time. Specifically, we propose that anticipated time pressure increases the likelihood of two types of planning, one short-term and the other long-term encompassing different strategies for eliminating or deferring activities. In addition, we discuss several behaviorally realistic such strategies. It is assumed that strategies differ depending on whether an activity satisfies physiological needs, is performed because of institutional requirements or social obligations, or is performed because of psychological or social motives. Strategies are also assumed to differ depending on the degree to which planning is feasible. Computer simulations of available activity data are presented to illustrate consequences of the different strategies on time pressure and activity agendas.     

Pantograph/Catenary Dynamics and Control

The pantograph-catenary system with its dynamic behaviour turned out to be a crucial component for new train systems required to run at higher speeds. With the present systems, operational limitations have to be accepted when running with several pantographs in the train set, when tilting trains are employed, when running on low quality catenary sections or when stricter noise reduction regulations are forcing lower noise emissions also for the pantographs. This paper gives an overview of the methods to describe the catenary and the pantograph system dynamics. Furthermore, aspects concerning the interaction between current collectors and overhead equipment, the acquisition of the model data and the verification are presented. Finally various constructions of passive pantographs and proposals for active control concepts are discussed.     

A moving bottleneck

Suppose that a vehicle or convoy enters a two-lane unidirectional roadway and travels at a velocity v^* less than the prevailing traffic. This moving bottleneck may cause a queue to form as vehicles try to pass the obstruction. It is shown that by going to a moving coordinate system traveling at velocity v^* the analysis of this can be transformed into a corresponding analysis of flow past a stationary bottleneck. The theory is then extended to investigate possible consequences of trucks on grades.     

Strategies for Serving Peak Elevator Traffic

—Suppose that in an office building of moderate height (5 to 20 floors) elevator traffic during peak periods is predominantly between a lobby floor and various upper floors. We compare the waiting plus riding time and the average number of passengers carried per trip for various strategies. In particular, if two (or more) elevators serve the same group of floors (a common strategy), the waiting plus riding time would typically be (slightly) less if one split the group into two parts and had each elevator serve separate parts of this group. The latter strategy would have considerably fewer passengers per trip. It may also be advantageous to have a single elevator serve different floors on successive trips. Seldom would it be advantageous for an elevator to serve more than 2 or 3 floors on any trip. If elevator systems used more efficient strategies during peak periods, buildings would not need as many elevators.