Transport Research Forum

Permanent URI for this communityhttp://192.248.9.226/handle/123/17946

Browse

Browsing Transport Research Forum by Subject "AADT"

Filter results by typing the first few letters
Now showing 1 - 3 of 3
  • Thumbnail Image
    item: Conference-Abstract
    Development of pavement performance and prediction models for flexible road pavements in Sri Lanka
    (Department of Civil Engineering, University of Moratuwa., 2019-09) Karunarathna, EPN; Pasindu, HR; Pasindu, HR
    International Roughness Index (IRI) is a pavement performance indicator which reflects not only the pavement condition but also the ride quality and comfort level of road users”. “Many highway agencies around the world consider the initial IRI value (IRI just after construction) as a quality assurance criterion while the prevailing IRI of a pavement as an indicator of required pavement maintenance actions or reconstruction needs. The aim of this paper is to develop an accurate IRI prediction model for Road pavements in Sri Lanka using linear regression analysis”. This model was developed based on data obtained from Road Development Authority (RDA) of Sri Lanka collected mainly using the Road Survey Vehicle. Models were developed for National Highways (A and B Class Roads) only. Further, variation of IRI for different climatic regions and for different vehicle compositions will be analyzed. The key parameters that the IRI value directly related on a particular pavement was decided based on the literature and the availability of data. The proposed regression model from this paper predict IRI as a function of pavement age, Average Annual Daily Traffic (AADT), initial IRI (IRI just after pavement construction) and transverse cracks or alligator cracks combined length per unit area of the pavement. A set of available data was used to calibrate the regression model and using other set of data, relationship between the measured and predicted IRI values for the proposed model was observed using the coefficient of determination (R2 value) as a statistical measure to determine how close the data are to the fitted regression line, as the validation process. The proposed model yielded an R2 value of 0.58. To identify critical parameters in above relationship statistical coefficient p-value was used. Then the variation of IRI was analyzed for different traffic categories. For AADT is greater than 50000 veh/day model yielded an R2 value of 0.36. For ADT in between 50000 to 10000 veh/day model yielded an R2 value of 0.21 and for category AADT less than 10000 veh/day model yielded an R2 value of 0.61. It was observed that due to some erroneous data the accuracy of the models became lower. So it was decided to remove pavement sections with age more than 25 years and some unacceptable values of IRI measurements using Engineering judgement and reanalyze. To identify the variation of IRI for different climatic conditions Western, Central and Northern provinces were selected. Western province has an annual average temperature of 27.4°C and an annual average Rainfall of 2420mm while Central province has 24.5°C and 1840mm and Northern province has 28°C and 1230mm. Models yielded R2 values of 0.18, 0.45 and 0.72 for Western, Central and Northern provinces respectively. Due to low R2 values it was decided to remove some unacceptable values of IRI measurements using and reanalyze.
  • Thumbnail Image
    item: Conference-Abstract
    Development of performance indicators to evaluate performance-based road maintenance contracts
    (Department of Civil Engineering, University of Moratuwa, 2020-12) Mullevithana, GL; Bandara, JMSJ; Perera, HLK
    Effective maintenance is essential to achieving sustainable development in Road sector. There are categories of maintenance activities as per the time of attendance, the period of attendance and frequency of attendance. Period for relevant activities is not specific. It is varying with the site condition and various parameters. Build- up the relationship between parameters helps to deliver the tangible results to programming, scheduling and budgeting for good governance, accountability and transparency in performance base maintenance. Road maintenance activities can be classified as per nature of attending; Routine, Recurrent, Periodic and urgent. Indicators of Road Surfacing and Road Marking on the paved road under periodic maintenance were selected to monitor and evaluation in this study. These activities are required to attend at periods of several years, the frequency depending on the damage caused by traffic and other factors. International Roughness Index (IRI) of road surface data was collected by the existing RDA database and Roadroid Mobile App with comparing last improvement details on selected road segments. Data for thickness, skid resistance and reflectivity of road marking were collected by the field test with following the tools of monitoring and evaluation (M & E) which can be used to improve the way achieving better result. Collected data were analyzed using panel regression, multiple regression and logistic regression tools. Initially stationary of data that represent variance and autocorrelation structure do not change over time was tested according to the Hadri Z statistic and results are significant providing selected stationary data. Out of random and fixed effect models, the most appropriate model is recommended by the Hausman test and that is the random effect model. According to this model, IRI gradually goes up due to Annual Average Daily Traffic (AADT) and within the periods, IRI will come to the critical level where the roads must be paid attention for the development. The range needs to be provided for periodically with achieving a critical range of IRI using selected stationary data models. Relationship between thickness, skid resistance & reflectivity of road marking with ageing is to be built up for future implementation and continue appropriate maintenance strategies.
  • Thumbnail Image
    item: Conference-Abstract
    Impact of bitumen content tolerance limit on performance of asphalt concrete pavements
    (Department of Civil Engineering, University of Moratuwa., 2017-07) Satheeban, V; Mampearachchi, WK; Pasindu, HR
    The development of corrugation along the longitudinal profile is one of the most common distresses in asphalt pavement. Especially road sections with high longitudinal slope, the problem is more severe than sections with a mild slope. This is because the slope decreases average speed of vehicles running upward, so the total loading time increases drastically. On the other hand, vehicles tend to apply brakes when running downward. The research aims at finding out how asphalt material (Bitumen & aggregates) properties have an impact on corrugation distress in sloped pavements. For this purpose, a recently constructed and heavily trafficked road (Ambepussa, Kurunegala, Dambulla A006) is considered. The above road has bitumen bleeding and corrugation issues within a short period after construction in some sloped pavement sections. The standard specification for construction and maintenance of roads and bridges has specified requirement for bitumen content and combined aggregate grading for mix design of asphalt with tolerances. The most common aggregate combined grading is Type 1 and 3 where Type 1 has finer and Type 3 has coarser particles. The gradation is one of the important characteristics of aggregates affecting permanent deformation of hot mix asphalt. The gradients of slopes are usually not considered when selecting the combined grading type for mix design of asphalt. The specification may be adapted to suit different conditions considering various criteria. For above road project, combined grading Type 1 and the bitumen content percentage by weight of total mix was adapted as +3% where the standard specification states ±3%. This leads the asphalt plant production to maintain bitumen content at higher than the design (maintain at 4.9% in the plant though design bitumen content was 4.8%. The investigations reveal that combined gradation of asphalt mix is towards the lower limits of specification values in corrugated pavement sections although within the tolerance. Further temperature and traffic loading to have an impact on sloped pavements. The recent traffic counts show that heavily loaded vehicles travel in the affected sections between 10.00 a.m. to 3.00 p.m. As per the investigation, it is recommended to always adopt Type 3 (Courser) combined grading for asphalt mix design for heavily trafficked roads in steep gradients and curves.