S. C. Wirasinghe

Nearly optimal parameters for a rail/feeder-bus system on a rectangular grid

Abstract An approximate analytical model of a rail plus feeder bus system that is serving a peak-period many to one type demand is presented. The underlying highway grid is assumed to be rectangular with the railway parallel to one axis. A simple graphical solution procedure is given for the general case when all the relevant rail/feeder-bus parameters are free. Explicit analytical solutions are given for the lower and upper bounds and for two special cases in which the station locations are pre-determined and the feeder-bus routes are relatively long, respectively. The model is applied to the Calgary (South Corridor) LRT system.

An approximate procedure for determining the number, capacities and locations of solid waste transfer-stations in an urban region

Abstract Many location problems may be separated into a series of interrelated macro, meso and micro decision-making states. The macro scale decision determines the type, capacity and number of facilities, the meso scale decision determines the location and allocation of facilities and the micro scale decision determines such considerations as routing and scheduling of service vehicles. This paper concerns the first two levels of decision-making. The present paper demonstrates the use of two models: (i) an analytical model that uses continuum approximations and methods of calculus to determine the number of facilities, the capacity and the approximate location of each that minimizes the sum of the transportation and facility costs for a slowly varying demand rate, and (ii) a traditional location-allocation model that determines more exactly the resulting locations and allocations. These two approaches have specific requirements in terms of data input, cost of data collection and cost of solution and, consequently, yield unique insights and benefits for practising planners. The strengths and weaknesses of the two models are complementary. This thesis is developed with an analysis of the Calgary, Alberta refuse collection and disposal system.

Airport gate position estimation for minimum total costs--Approximate closed form solution

A method to determine the optimum number of gate positions at an airport terminal, which minimizes the sum of the cost of gates and the cost of delays to aircraft is presented. It is based on an approximate procedure to determine the total deterministic delay to aircraft caused by a limited number of gates, given information regarding the peaking of the aircraft arrival rate, and the number of peaks per day. Closed-form solutions are obtained for the cases of one peak and several identical nonoverlapping peaks, respectively. The optimum number of gates required for the Calgary International Airport, based on a common gate use policy, is reported.

Walking distance minimization for airport terminal configurations

Passenger walking distance is a major consideration in determining the configuration of an airport terminal. Given the size of a terminal in terms of the number of aircraft gates, the mean passenger walking distance is derived based on: the fraction of arriving, departing and transferring (hub and non-hub) passengers; gate spacing; spacing requirement for aircraft maneuvering; and the terminal block dimensions. Pier, satellite, and pier-satellite terminal configurations are considered. It is assumed that all aircraft parking positions are capable of handling any type of aircraft and passengers are equally distributed among all the gate positions over the life of the facility. Two groups of hub transfers are defined to accommodate different levels of hub and spoke operations. The optimum terminal geometry in terms of the number of piers or satellites and their sizes, is obtained by minimizing the mean walking distance for all the passengers. The probability distribution of the walking distance of a passenger is generated by simulation. Given an acceptable walking distance, several statistical parameters that are suitable to compare the optimum geometries for different configurations are reported. It is shown that in most cases the lower and the upper bounds of the optimum number of piers or satellites are proportional to the square root of the total number of gates in the terminal. For a wide range of passenger mixes and numbers of gates, a semi-centralized pier configuration appears to be the best terminal configuration with respect to passenger walking. Guidelines for the selection of the best terminal configuration for non-hub, moderate-hub and all-hub (wayport) terminals are presented. The application of the proposed method in a terminal expansion situation is given.

Bus rapid transit – a review

Bus Rapid Transit (BRT) has been demonstrated to provide efficient and effective public transport that can even increase transit ridership and attractiveness within defined urban corridors in both developing and developed countries. The merit of the BRT system lies in its ability to provide a high quality public transit service with limited infrastructure and at a relatively low capital and operating cost. In this paper an attempt is made to review BRT characteristics in some detail. An overview of the elements of BRT systems: the running ways, vehicles, stations, as well as operational control, fare collection and passenger information systems is presented. This paper also discusses how these elements allows BRT services to achieve the speed, capacity, reliability, accessibility and operational safety characteristics that distinguishes such systems from regular express bus services. Each built BRT system is unique and depends on how these basic elements are designed and integrated. Environmental, social and economic impacts, users’ perception and modal shift towards BRT have also been critically reviewed. With the presence of local land use and transport policies that support high-density and mixed developments, BRT has been found to attract potential developments around stations and along its corridor, increasing land values and promoting sustainable development. As reported in the literature, the infrastructure costs vary greatly depending on the costs of land acquisition, station design, degree of separation from traffic, technological features and material, labor costs. Thus, BRT capital costs cannot be generalized and must be transferred carefully based on the changes of the input costs that vary from one place to another. The barriers to BRT that block the achievement of significant success in customer satisfaction and ridership gains are mentioned with specific case studies. The review of BRT indicates that in some cases it has similar performance to higher order public transit; however, it still has its unique characteristics that set it apart.

Rail Line Length in an Urban Transportation Corridor

The length of a rail line that will minimize total transportation user and operator costs, and the threshold demand necessary to ensure that the resulting length of the rail line is nonzero are investigated for an urban transportation corridor. A density of demand for travel to the central business district CBD represented by a general function Px passengers per unit length of the corridor where x is the distance from the CBD is considered. The line-cost as a function of x, the costs of the rail fleet, rail and bus operating costs and passenger time costs are also considered in the formulation. The fleet size is formulated considering the peaking of demand relative to time. When the line cost is nonuniform there could be several line lengths at which the total transportation cost is minimized or even maximized locally. When the line cost per unit length is uniform, a minimum transport cost rail line of nonzero length exists only if the net gain in travel time and operating cost of transporting the total ridership a unit distance by rail, when compared to bus, exceeds the marginal line and fleet costs per unit length. In either case, the minimum transport cost rail line length can be determined easily. The effects on the line length of shifts in demand are investigated. Closed-form solutions for the line length are obtained for the cases of sectorial and rectangular corridor-sheds with uniformly distributed demand per unit area.

Wayfinding in the passenger terminal of Hong Kong International Airport

One of the important features of airport passenger terminal layout is passenger orientation (wayfinding). Many people have difficulty in locating their desired destination within an airport despite the availability of information signs. This paper describes the use of a quantitative measure, or visibility index, to evaluate the ease of orientation in the departure lounge of Hong Kong International Airport. Based on the visibility index, a new set of level-of-service standards for orientation is proposed. The findings of this paper are compared with those of previous studies.

Evacuation behaviour of households and drivers during a tornado

Abstract With increasing concerns over the possibility of tornadoes in highly populated areas in Canada, emergency managers are looking into ways to mitigate the impacts of tornadoes. Given that tornadoes can cause enormous destruction, early warnings and proper evacuation actions are critically important in helping save lives. In this paper, a survey was conducted to analyse the evacuation behaviour of households and drivers during a hypothetical tornado warning situation in the city of Calgary, Alberta. Nearly 500 Calgarians took part in the online survey and provided information on how they would respond to tornado warnings after receiving them. This paper presents the results of the survey. Using probit models, the factors influencing these evacuation decisions are identified and discussed in detail. The results of the household evacuation model show the importance of improving awareness about the safest locations during a tornado. It further highlights the need for targeting the population under the age of 30, who are more likely to take unsafe evacuation actions. The model for evacuation of drivers shows that several factors, such as knowing the difference between a watch and a warning, awareness of safe cover, receipt of warnings through natural environmental cues and the level of education, trigger evacuation actions in avoiding a tornado threat.

Optimum zone structure during peak periods for existing urban rail lines

The problem of optimizing the service along an existing two-track rail line by adopting a zone-stop schedule during the peak periods is investigated. A dynamic programming technique is employed to determine the number of zones, the stations that belong to each zone, the headway between trains to the same zone and the fleet size. The general objective of the analysis is to minimize the total transportation cost, defined as the sum of the costs of time to the passengers and the relevant rail capital and operating costs. The optimization problem is subject to several constraints including avoidance of train conflicts, limitations on the value of the headway and an available fleet size. The applicability of the model is demonstrated through a numerical example using field data.

An aggregate demand model for intercity passenger travel in Sri Lanka

Inspite of the inherent weaknesses in aggregate demand models, they continue to be used in everyday applications, especially in developing countries. The largely data intensive disaggregate model preclude its application in many cases. This paper attempts the formulation and calibration of an aggregate total demand model for estimating inter-district passenger travel by public transport in Sri Lanka. In its process, an investigation is made of the common problems in the aggregate approach while examining possible remedial measures to improve the accuracy and (hence) the usability of the aggregate model. It is argued that commonly used variables and functional forms are inappropriate for making accurate estimates in developing countries. Consequently, the model calibration is shown to incorporate variables representing urbanisation, under-development, transfers, a mode-abstract cost function and intrinsic features. The necessity for functional form for each variable to be based on behavioral assumptions that are tested using the Box-Cox transformation for ensuring the best fit of the data is also observed. Although, the model form was calibrated for Sri Lanka, the model is generalised in order for its applications to other countries as well as, both, inter-district and intercity travel demand estimation.