Browsing by Author "Hassan, Rayya A."

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    Assessing the Impacts of Pavement Surface Condition on the Performance of Signalized Intersections
    Hussein, Nasreen A.; Hassan, Rayya A.; Evans, Robert (2015-06-04)
    Signalized intersections are one of the most dangerous places on the road network as they carry a very high crash risk. This may be exacerbated by inadequate pavement surface condition. The main objective of this study was to assess the effect of pavement surface condition (in terms of skid resistance, roughness and rutting) at intersections and approaches on users' safety. In particular, this paper studied the change in crash frequency for numerous signalized intersections before and after surface treatment. Around one hundred sites were selected based on historical crash incident data and pavement maintenance records. Pavement condition data was extracted for these sites one year before and one year after surface treatment. For all sites, a minimum of three years crash data was used before and after treatment. Reported in this paper are the findings of an assessment of the changes in crash rates, types and severity due to surface treatment. Overall, assessment of the effect of surface treatment revealed a statistically significant reduction in crash rates of 0.49 at 95% confidence level with a p value of 0.006, based on a paired t-test. Negative binomial regression analysis was performed using pavement condition data, traffic volume and speed limit as the predictor variables of crash frequency. The results showed that both traffic volume and the interaction between traffic volume and skid resistance were significant contributors to the crash occurrence. However, for after treatment no independent variable had a significant contribution to the crash occurrence.
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    Effect of Traffic and Environmental Factors on Roughness Progression Rate of Sealed Low Volume Arterials
    Alaswadko, Nahla; Hassan, Rayya A.; Evans, Robert (2015-06-04)
    A high proportion of the rural arterial network in Victoria /Australia are low volume roads built of sealed granular pavements, which are important routes for freight movement between rural centres. Investigation into rehabilitation of these arterials is triggered when roughness reaches a certain threshold level. To assist road agencies in their long term planning, a project has been initiated to develop absolute deterministic deterioration models for these roads. A representative sample network of low volume arterial roads has been selected and all relevant data including pavement condition are collected. The network covers a representative range of traffic loading, subgrade reactivity level and environmental factors. For each highway section, raw longitudinal profile data from at least four years was used to determine roughness progression over time. All profile data was aligned and then cleaned and filtered to ensure that the same length of road profile was compared over time. To remove the influence of maintenance activities, only sections with positive progression was included. Multiple linear regression analysis was used to develop models for these sections to predict pavement roughness over time as a function of a number of contributing variables. The output of the analyses was used to evaluate the significance and contribution of the different factors including traffic and environmental conditions. This paper provides a description of data preparation and analysis. It was observed that higher traffic loading and soil reactivity, poor drainage and climates with high seasonal variation increase roughness progression rate.