Airline productivity redefined: An analysis of U.S. and European carriers

Productivity, in terms of net value added per man-year of labor and capital input, provides a more useful yardstick of airline efficiency than the widely used indices representing average unit costs or labor productivity. Large variations in productivity between airlines, in particular between U.S. and European airlines, can be explained almost entirely by differences in level of service, demand patterns and route characteristics. A regression model calibrated on 1975 data for fourteen U.S. and fourteen European scheduled airlines indicates that productivity could be increased by changes in network shape though a more liberal exchange of traffic rights, greater specialization (in particular the limited involvement of scheduled airlines in the very low yield charter market) and consumer choice — by offering higher frequency, multi-city services.     

Heave-Pitch-Roll Dynamics of Flexible Vehicle in Variable Velocity Run

Analysis for response statistics evaluation of a flexible vehicle travelling with variable velocity over nonhomogeneously profiled flexible track is presented with a heave-pitch-roll model. The vehicle body is idealised as a flexible member with variable cross-section, inertia, damping and stiffness distributions. The vehicle may also have variable section slender elastic attachments. Coupled dynamics with rigid body heave-pitch-roll modes and elastic bending-torsion modes of the vehicle body along with coupled bending-torsion modes of the attachments are considered. Equivalent linear suspension system characteristics are employed for developing the analysis. Numerical results are presented for an aircraft with tricycle landing gear arrangements and comparison is made with other models.     

Some comments on activity-based approaches to the analysis and prediction of travel behavior

This note presents the author's conjectures on several symptoms raised in Kitamura's assessment of activity-based travel analysis. It focuses on some of the characteristics of the development of activity-based approaches that may help explain their limited impact to date on travel demand forecasting practice. The broader role and potential contributions of activity analysis of the demand for infrastructure systems are emphasized.     

A model for allocating car parking spaces in universities

In this paper a linear programming model has been presented for determining the optimum allocation of existing car parking facilities for different classes of users within a closed community, of which a university is a typical example.     

Aerodynamics of Road- and Rail Vehicles

The technical state-of-the-art of aerodynamics of ground transportation vehicles is reviewed. Currently available theoretical calculation methods and experimental simulation techniques as well as typical results illustrating the impact of aerodynamics on vehicle performance and running characteristics are summarized and the interactions between vehicle system dynamics and aerodynamics are adressed. Correlation of theoretical and experimental data show the present potential of vehicle aerodynamics and point to fields in which further research work is necessary.     

Estimation of parking accumulation profiles from survey data

Parking accumulation profiles at car parks are time-dependent quantities that require data from lengthy observation surveys. However, it is found that car parks can be clustered into groups based on the similarity in the shape of their accumulation profiles. This procedure increases the efficiency of the survey data collected for this purpose. This paper describes a method developed to estimate aggregate parking accumulation profiles at different districts in a city. The planning of the survey conducted in Hong Kong in the year 2000 and the results of the data analysis are also described.     

Introducing alternative fuel vehicles in Hong Kong: views from the public light bus industry

Hong Kong was the first place in the world to implement a trial scheme to convert all public light buses (PLBs) on the road from diesel to alternative fuel vehicles (AFVs). The scheme, however, did not receive much support from PLB operators. At present, there is a rich literature on households’ demand for AFVs (especially in the USA). However, there have not been many studies about the demand for commercial AFVs in the business and public transport sectors. Since light buses running on alternative fuels are not widely available in the Hong Kong market, a stated preference (SP) survey was conducted to solicit the preferences of PLB operators on eight commercial vehicle attributes and seven forms of government support. The SP data are analyzed by multinomial logit (MNL) models. Detailed analyses on market segmentation and price elasticities follow. The results are of theoretical and practical significance.     

TECHNICAL NOTE

This paper presents an advanced control method in application of automotive systems. An adaptive fuzzy logic controller based on self tuning control methodology has been implemented and used to control the vehicle velocity. Fuzzy rules and reasoning are utilized on-line to determine the throttle angle, spark advance and braking force. Simulated results, as presented in this paper show the adaptive fuzzy control is well suited for vehicle speed control with a nonlinear dynamic behaviour of the engine.     

On the reserve capacities of priority junctions and roundabouts

The concept of reverse capacity of a whole junction has been used extensively in the design of signal-controlled junctions. This concept, however, has not been applied to priority junctions and roundabouts, probably because of the complicated demand and supply relationship. When the demands on the approaches to the junction increase, the capacities of those non-priority approaches reduce at different rates. This makes the calculation of reserve capacity of the whole junction not a straightforward task. Using the definition of reserve capacity of a whole junction in Allsop (1972; Transpn Res. 6, 245–255), explicit formulae for the estimation of reserve capacities of priority junctions and roundabouts are derived in this paper. Numerical examples are given to illustrate the usefulness of these formulae.