International Conference on Advances in Highway Engineering & Transportation Systems

Permanent URI for this communityhttp://192.248.9.226/handle/123/19000

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item: Conference-Abstract
Accommodating road accident records in a comprehensive highway management system
(Department of Civil Engineering, 2011-07) Bandara, JMSJ; Silva, SA; Rajapaksha, RPGKS; Pasindu, HR
It has become important to improve planning, design, construction, operation and maintenance standards and manage road system efficiently. There are number of management systems such as pavement management system, road inventory systems, accident data recording system, traffic and passenger demand models, traffic assignment models have been established to handle different stages of road transport. As different organizations are responsible for the above different processes it is imperative to have these systems coordinated to have an integrated highway management system that will share information, expectations and experience. Today road accidents have become a significant negative impact to all road users. To reduce the number of accidents, it is important that manage the accident data in systematic manner because it will provides lot of information. This data is very important to traffic and highway engineers because it helps them to identify the unsafe location of the roads and the reasons for that. This is essential in road improvement projects to carry out safety audits and find the solution to minimize the number of accidents. This paper presents how a road inventory and accident data system could be integrated to share information from one another. In addition the paper highlight how road inventory data and accident data can be used to analyze accidents at road link, road type or administrative area vise and identify accident prone locations or reasons for different types of accidents. The programme was written using VBA (Visual Basic for Applications) which is more relevant to customize ArcGIS Desktop Applications to store the data in a Microsoft access database and filter the database using the developed VBA interface. For example, users can find out the number of accidents on a location according to various crash factors contributing to the accident from human side, vehicle side and road environment side. According to filtering combinations, model is developed to show the number of persons died, injured and detail list of accidents. The model has capability to connect road inventory data and accident data with attribute tables in ArcGIS. Therefore, engineers can directly use the GIS tools to represent and analyze the above data in an efficient manner.
item: Conference-Abstract
Development of guidelines for traffic signal coordination for intersection clusters
(Department of Civil Engineering, 2017) Jayasooriya, NK; Bandara, JMSJ; Pasindu, HR
With the ever-increasing traffic congestion, it is needed to initiate sustainable traffic management solutions. There is a need to establish signal design standards taking in to account the latest trends in traffic signal development so that there will be consistency in traffic signal designs and also to make provision to incorporate future coordination and other automation such as monitoring violations and gathering traffic flow information for real time updates. More importantly standardization will minimize user confusion and improve safety at traffic signals and help improving traffic flow and user satisfaction. The congestion issues that are related to signalized intersections are not only inherent to a particular intersection, but rather can be a result of the signal arrangements at nearby intersections. This research identifies the issues with the typical intersection arrangements, and aims at developing a guideline to be followed for traffic signal designs especially when traffic signals are to be coordinated intersection clusters. The necessity of a properly calibrated software for the local condition has been identified as a key component in related literature. VISSIM traffic simulation software was calibrated for the Sri Lankan condition after collecting information from more than 10 intersections in and around Colombo. From the video surveys and manual observations considered, the traffic volumes along with the turning movements, vehicle mix and queue lengths were obtained and compared with the simulated results with an accuracy of ±10. With the calibrated VISSIM software, the guidelines to be followed were developed considering the factors such as; identification of the coordinated phase, determination of individual signal timings for intersections, determination of phase timings for coordinated & non-coordinated directions and optimizing the offsets. The developed guidelines were tested for the Baseline Road intersection cluster and simulation results shows significant delay reductions over xx% for any approach can be achieved in the coordinated directions without adversely affecting the non-coordinated directions.
item: Conference-Abstract
Effect of traffic composition on capacity of two-way two-lane, roads under mix traffic condition
(Department of Civil Engineering, 2017) Rajapaksha, RPGKS; Bandara, JMSJ; Pasindu, HR
Traffic performance of a road section is expressed in terms of Level of Service (LOS). The Highway Capacity Manual (HCM) developed by the Transportation Research Board of the National Academies of Science in the United States provides procedures to determine LOS based on analysis of capacity of a road. It divides the quality of flow into six levels ranging from level A to F. These definitions of quality are based on measures of effectiveness of the road which include speed, travel-time, density and delay. Road development authorities in Sri Lanka are adopting the methodologies given in the HCM due to the lack of guidelines specific for the country. However, the HCM methodologies may not depict the correct traffic performance of roads owing to the nature of the mix of vehicle types in the traffic stream, the lack of lane discipline and irregular road side activities. This may lead to incorrect decisions in planning, designing, maintenance, rehabilitation, and operation of roads. Therefore, it is necessary to study traffic performance in Sri Lanka, and to evaluate the transferability of methods used in other similar countries in order to develop appropriate and applicable approach to mix traffic Condition. Subsequently, in order to evaluate traffic performance, it is important to study about operational characteristics of traffic stream. In a pilot study under this work, capacity of a road was found to be affected by the traffic composition and control condition. Therefore, characteristics of vehicle composition in different capacities have been considered and study was focused to two waytwo lane roads. Different size, power, and maneuverability performance of vehicles cause significant level of friction to the movement of other vehicles in a mix traffic stream. For an example, in a high traffic volume stream, a large proportion of motorized two wheelers and three wheelers are able to move with speeds closer to their free speeds due to the ability of utilizing smaller gaps in the traffic stream, while the large-size vehicles are subjected to significant speed reduction. Characteristics of fundamental traffic flow parameters (Speed, Density and Flow) in traffic streams with different compositions of vehicles were studied. One-Sample Kolmogorov Smirnov test was performed to check normality of speed of collected data samples under prevailing conditions and it has shown that speed distribution is significantly deviate from normality (P-value < 0.05) under different compositions and traffic volumes. It is observed that speed distribution shows bi-modal distribution in roads which wheelers and three wheelers. One-way analysis of variance (One-way ANOVA) tests was carried for speed characteristics of group of two wheelers, three wheelers and four wheelers. Null hypothesis (Ho) that there will be no significant difference between different groups of vehicle speed sample means was rejected with 95% confidence level (P-value < 0.05). Therefore, vehicle composition has described as separate groups of two wheelers, three wheels and four wheelers. Modified continuity equation for heterogeneous driver population was used to calculate densities of traffic streams. Different traffic flow models which used to model two-lane traffic flow behavior had been tested under prevailing conditions. Greenshield traffic flow model has showed strong correction between flow and speed and it was chosen to develop speed-flow models. Finally, empirical speed - density and speed - flow curves were developed for different compositions of vehicles in order to evaluate the capacity variations under mix traffic condition.
item: Conference-Abstract
Pedestrian facilities in urban environments using "walkability" measures
(Department of Civil Engineering, 2011-07) Dias, I; Bandara, JMSJ; Pasindu, HR
Pedestrian facilities in urban environment are sometimes less appealing in residential/ recreational areas or insufficient to serve the peak hour pedestrian flows in commercial areas .There is no proper mechanism to evaluate the deficiencies in pedestrian facilities. Furthermore, increasing trend in motor vehicle use and pedestrian related accidents are the evidence of inadequate facilities for pedestrians. This research proposes a scoring model to evaluate pedestrian facilities in urban environment using "Walkability" measures. Walkability is an idea of quantifying the safety and desirability of walking routes. The model can be used to evaluate pedestrian facilities in road links to compare different road links or to identify deficiencies in a given road. At present walkability is evaluated using qualitative measures that are very subjective. Existing methods of evaluating walkability was carefully studied and the limitations and weaknesses were identified. Methods to evaluate as many features were proposed and validated. Among these factors, several features of sidewalks such as width, elevation difference, paving type and continuity are assessed. Modal conflict, the conflict between pedestrians and bicycles/ motorized vehicles is measured using passing and meeting number of events. Availability of crosswalks and delay at un-signalized and signalized crosswalks are some of the parameters used to evaluate crossing facility. A good mix of land use where the number of destinations (Groceries, restaurants, schools, health facilities, Cinemas, etc.) is higher is considered to be a good walkable neighborhood. Availability of pedestrian facilities including, benches, shades, bus halts with seats, pedestrian information boards, proper street lighting add scores to a road link. Addressing differently able people; the blind, the disabled, push carts, children is also taken in to consideration while universal accessibility is believed to be at vital importance. Apart from the above quantitative measures, parameters such as, aesthetics is also assessed qualitatively. A score as a percentage is finally obtained from the evaluation where 100% means a perfect road to walk and 0% means a disasterfor walking.
item: Conference-Abstract
A revisited model estimation for international passenger demand at Bandaranaike international airport, Sri Lanka
(Department of Civil Engineering, 2011-07) Piyathilake, LWD; Priyadarshani, GAC; Bandara, JMSJ; Pasindu, HR
Regression models are quite commonly used in air travel demand estimation. This paper presents a passenger forecast model for the Bandaranaike International Airport, which is the single international gateway for passengers travelling in and out of Sri Lanka at the time of conducting the study. The study hypothesize that the parameter estimates for the demand determinants of air travel in Sri Lanka has changed overtime and the model estimation revisit the analysis carried out by Bandara and Wirasinghe (2001) to estimate passenger demand for medium sized airports. Post fact analysis of the model proposed by Bandara and Wirasinghe (2001), revealed statistically significant differences between prediction and actual values with outliers to the 95% confidence interval bands established for the regression model. The deviations were results of the effects of 9/11 incident and heightened civil unrest experienced time to time in Sri Lanka during the past ten years. An empirical validation to the existing model was identified as necessary, since Sri Lanka is at the juncture of post war development proposals to promote the country as an aviation hub. A further objective of estimation was to justify the best time scale of past data to be used in model calibration for passenger demand forecasting using econometric models. The new estimates are established using a multiple regression model with two variables; Real Gross Domestic Product (RGDP) and a Dummy (TJ variable for severe terrorism/civil unrest conditions. Findings of the previous study is revalidated empirically by concluding that using 12-15 year past data for model calibration meets multiple regression assumptions at its best with time series data, avoiding spurious regression. The results suggest that the model forecasts ideally fits with the actual in the medium term. Hence, updating the model on a roll-out basis increases the validity of the model estimates.

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