Browsing by Author "Perera, Loshaka"

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item: Conference-Full-text
New methodology for developing driving cycle(s) for Sri Lanka; case study, Colombo, Sri lanka
Galgamuwa, Uditha; Perera, Loshaka; Bandara, Saman
Even though driving cycles have been adopted around the world in different type of applications, the data needed for each steps is costly and time consuming. Majority of the Developing countries do not have systematic data bases for traffic related information such as origin-destinations, vehicle kilometers, average annual daily traffic etc. for majority of road links. Meager amount of available data is not sufficient to develop a driving cycle. Even though the data is collected, significant effort has to be made to construct a driving cycle that closely matches to the population data set. This paper gives simplified methodology for developing driving cycles using different approaches for route selection, data collection and cycle construction. For the route selection the available methods have been combined together and modified to suit for developing countries where no details traffic flow information will be available. Also a method was adopted for data collection by dividing selected routes in to links and grouped them according to daily traffic to optimize the cost for data collection. Road links were divided using physical junctions on the road and routes were selected using traffic generators and attracters combined with Origin Destination data. Also methodology was developed for synthesize data population using collected data from road links. Another issue for cycle construction is to construct a cycle which is close to population parameters. Using existing methods many cycles have to be constructed until the acceptable cycles is generated. New methodology has been adopted to develop driving cycle to match the population parameters and then to select data for driving cycle using Markov chain. As a case study Colombo, Sri Lanka has selected to apply the new approach of driving cycle construction for developing countries.
item: Conference-Full-text
Prioritizing transport infrastructure projects at early stages of projects
Gamalath, Isuru; Perera, Loshaka; Bandara, Saman
Investment on transport infrastructure is a significant component in a country’s budget as it is identified as a key factor to facilitate the country’s development. At the same time demand for transportation is positively correlated with the development. With this increasing demand for transport infrastructure and limited funding available, it is necessary to prioritise appropriate projects. Current appraisal practices at the early stages of projects fail to identify some important criterions and therefore, may ultimately end up not selecting the most appropriate project(s) which addresses contemporary concerns. Therefore the objective of this study is to identify a cost effective method and factors that should be considered in evaluating alternatives at the early stages of transport infrastructure projects. Both academic and grey literature was reviewed to identify current practises; methodologies and factors concerned in the recent past. Most of the time feasibility reports used descriptive format and often gave vague conclusions. Therefore the final selection of alternative(s) is implicit. A performance matrix was developed in this study based on multi criteria analysis linear additive model. This method was primarily selected as it is easy to use in practise. In addition to the traditional criterions, this matrix contains new criterions that should be looked into with the current interests. A case study for Kandy expressway alternative selection based on this developed performance matrix is presented in this paper. In addition to the new matrix, a modified scoring system was used in the analysis to minimise the variations, as scores are given by different experts. Further, analysis was compared with the view of different experts and results of sensitivity analysis to address the possible arguments on weight given to each criterion.
item: Article-Full-text
Toll and subsidy for freight vehicles on urban roads: A policy decision for City Logistics
(Elsevier, 2021) Perera, Loshaka; Thompson, Russell G.; Wu, Wenyan
Toll roads constructed under public-private-partnerships (PPP) are very common around the world. Due to the high capital cost invested and high risks associated with subsequent returns, investors are concerned about future revenue. Charging high tolls from freight vehicles is a common practice, especially in urban areas. As a result, freight vehicles tend to divert from freeways (toll roads) to highways and arterial roads to minimize their costs, but this may cause more damage to infrastructure and environment, thus more costs for society and the environment. Consequently, developing an effective solution for toll charges for freight vehicles is a complex City Logistics problem involving multiple stakeholders with multi-objectives. This research investigates total costs (economic, social and environmental) associated with freight transportation based on existing toll structures for a toll road in Melbourne, Australia. Using a real case study, a step by step process was developed to illustrate the inefficiencies that exist in the present rigid toll charging mechanisms and how these inefficiencies can be corrected considering multi-stakeholder objectives and the overall impacts. This research identifies an optimal set of solutions that can be considered by decision-makers for implementation considering trade-offs between multiple management objectives. By considering subsidies, this research also identifies a good practical solution for minimizing the total cost of urban freight transportation while satisfying the investor needs. This policy decision is illustrated and related issues are discussed.