Duration of trip-making activities by men and women

The purpose of this paper is to present the results of a survival analysis for the duration of particular trip-making activities based on sex. Specifically, this study investigates the duration of those activities related to household and family support shopping, personal business, and free time and how these durations vary between men and women. It was found that there were no significant differences in the survival curves (i.e., durations) of free-time or personal business activities; this suggests that men and women spend approximately similar amounts of time on these activities, although it is not known if the activities themselves are similar (for example, banking versus getting gas). Alternatively, sex was found to be a very significant indicator of the duration of household and family support shopping activities. In the model specification, assuming all variables except sex are the same, it was found that women were 1.32 times more likely than men to spend a longer period of time in a household and family support shopping activity. Additionally, it was found that women are 1.33 times more likely than men to have a longer household and family support activity duration if the activity is nested in the journey to work trip.     

Effects of subsidies on urban public transport

Because of a general trend of increasing costs of public transport operations and higher subsidies (in some cases accompanied by falling patronage) the European Conference of Ministers of Transport (ECMT) initiated a study of subsidisation and sought the help of the Transport and Road Research Laboratory. The study, in which eighteen countries took part, was concerned with the aims of subsidy, the sources and conditions attached to subsidy, trends in subsidies and the effect of subsidies on patronage, fares, service levels, costs and productivity.The qualitative information concerning the aims of subsidy was analysed in relation to the likelihood of achieving such aims, taking into account current experience of attempts to switch car drivers to public transport. The quantitative information on trends referred to public transport stage services covering where possible the entire country and relating to the period 1965–77; these data were supplemented by data from 59 cities in different parts of the world collected in the course of a TRRL-sponsored study of travel demand factors. The relationship between patronage and service levels, and between subsidies and various operating factors, including costs and productivity, were studied using regression analysis and the general conclusion reached was that although the major part of the subsidy paid was reflected by reduced fares and improved service levels there may well have been some leakage into higher unit costs and manning levels.     

On Grey's critique of generalised cost

It is argued that some of Grey's criticisms (this issue) — including those at the centre of his argument - are based on faulty logic, invalid premises, or lack of clarity about what current practice actually is. An appropriate definition of generalised cost, together with a sensitive disaggregation of major groups of the population, can help to increase the reliability of forecasts and provide a consistent underlying framework for analysis of otherwise disparate projects.Some of Grey's criticisms are more valid, however, and there is a case for some changes in current practice. This can best be done by adapting, rather than abolishing, the tool of generalised cost, since the alternatives available seem even more flawed, in terms of being either arbitrary or inconsistent.The author gratefully acknowledges the help of M. H. Fairhurst and M. G. Langdon, who suggested some of the lines of argument in this paper. Opinions are those of the author, not the Greater London Council.     

Planning for implementation

Although the urban transportation planning process has evolved into the most sophisticated of all urban planning processes, the increasirig difficulty in implementing long-range transportation plans in urban areas today suggests basic questions concerning the process which deserve critical examination.Planning for implementation of urban transportation programs, particularly during periods of rapidly changing human values, requires a continuing re-evaluation of both technical and organizational strategies and their interrelationships.This paper raises some fundamental questions about the traditional activities and relationships that have characterized most urban transportation planning programs in the past. It also suggests a number of strategies, both technical and organizational, that may contribute to the implementation of plans and programs resulting from the transportation planning process.The first portion of this paper discusses the implications of not providing transportation services to match metropolitan growth. The experience of the Washington Metropolitan Area over the past decade is used to illustrate these implications.A discussion of organizational and institutional constraints upon the planning process follows. Then, the implications for the planning process are explored, and the scale of planning is reviewed as well as the need for monitoring the performance and impact of facilities.Next, the paper deals with the need to broaden the range of solutions to transportation problems, including consideration of economic and land development policies to reduce travel demand, as well as the provision of new facilities.Finally, techniques for involving decision-makers in the planning process are discussed. Examples of special project activities in the Washington area are used to illustrate these techniques and their value.     

Container ship turnaround times at UK ports

This paper looks at the relationships between ship size, handling rate and ship berth time for five major ports in the United Kingdom. The results show that there is no simple linear relationship between these variables. The causes and implications of this are discussed.     

Science Needs for Sea-Level Adaptation Planning: Comparisons among Three U.S. Atlantic Coastal Regions

To identify priority information needs for sea-level rise planning, we conducted workshops in Florida, North Carolina, and Massachusetts in the summer of 2012. Attendees represented professionals from five stakeholder groups: federal and state governments, local governments, universities, businesses, and nongovernmental organizations. Over 100 people attended and 96 participated in breakout groups. Text analysis was used to organize and extract most frequently occurring content from 16 total breakout groups. The most frequent key words/phrases were identified among priority topics within five themes: analytic tools, communications, land use, ecosystem management, and economics. Diverse technical and communication tools were identified to help effectively plan for change. In many communities, planning has not formally begun. Attendees sought advanced prediction tools yet simple messaging for decision-makers facing politically challenging planning questions. High frequency key words/phrases involved fine spatial scales and temporal scales of less than 50 years. Many needs involved communications and the phrase “simple messaging” appeared with the highest frequency. There was some evidence of geographic variation among regions. North Carolina breakout groups had a higher frequency of key words/phrases involving land use. The results reflect challenges and tractable opportunities for planning beyond current, geophysically brief, time scales (e.g., election cycles and mortgage periods).     

Analysis and optimization of air suspension system with independent height and stiffness tuning

Suspensions play a crucial role in vehicle comfort and handling. Different types of suspensions have been proposed to address essential comfort and handling requirements of vehicles. The conventional air suspension systems use a single flexible rubber airbag to transfer the chassis load to the wheels. In this type of air suspensions, the chassis height can be controlled by further inflating the airbag; however, the suspension stiffness is not controllable, and it depends on the airbag volume and chassis load. A recent development in a new air suspension includes two air chambers (rubber airbags), allowing independent ride height and stiffness tuning. In this air suspension system, stiffness and ride height of the vehicle can be simultaneously altered for different driving conditions by controlling the air pressure in the two air chambers. This allows the vehicle’s natural frequency and height to be adjusted according to the load and road conditions. This article discusses optimization of an air suspension design with ride height and stiffness tuning. An analytical formulation is developed to yield the optimum design of the new air suspension system. Experimental results verify the mathematical modeling and show the advantages of the new air suspension system.     

Run-off-road and recovery – state estimation and vehicle control strategies

Despite many advances in vehicle safety technology, traffic fatalities remain a devastating burden on society. With over two-thirds of all fatal single-vehicle crashes occurring off the roadway, run-off-road (ROR) crashes have become the focus of much roadway safety research. Current countermeasures, including roadway infrastructure modifications and some on-board vehicle safety systems, remain limited in their approach as they do not directly address the critical factor of driver behaviour. It has been shown that ROR crashes are often the result of poor driver performance leading up to the crash. In this study, the performance of two control algorithms, sliding control and linear quadratic control, was investigated for use in an autonomous ROR vehicle recovery system. The two controllers were simulated amongst a variety of ROR conditions where typical driver performance was inadequate to safely operate the vehicle. The sliding controller recovered the fastest within the nominal conditions but exhibited large variability in performance amongst the more extreme ROR scenarios. Despite some small sacrifices in lateral error and yaw rate, the linear quadratic controller demonstrated a higher level of consistency and stability amongst the various conditions examined. Overall, the linear quadratic controller recovered the vehicle 25% faster than the sliding controller while using 70% less steering, which combined with its robust performance, indicates its high potential as an autonomous ROR countermeasure.