EVALUATION OF CONNECTIVITY INDICES AND LEVEL OF SERVICE OF AKURE ROAD NETWORK

Abstract

This study was aimed at evaluating the road connectivity indices and level of service (LOS) of Akure road network with a view to further determining if there exist a significant relationship between road connectivity indices and LOS. The study area was divided into 24 traffic analysis zones (TAZ) and data for the study were acquired from these zones. To determine the road connectivity indices and other road network parameters, the study area road network map was digitized and converted into a graph network in which road segments were represent by arcs/edges and intersections and endpoints were represented by nodes/vertices. Traffic data were collected during peak period on an hourly basis both weekdays and weekends at the highway in the centroid of the TAZ considered. Pearson correlation analysis were carried out to determine the relationship between the connectivity indices and LOS. Analysis of data collected showed that road density is generally high in the study area with an average value of 3744 m/km2 (3.74 km/km2) (3744 m/km2 > 120 m/km2). The average Alpha index in the study area was 0.1, while the highest Alpha index recorded was 0.3 out of a maximum of 1.0 thereby showing that the possible number of segments between existing nodes in the study area have not been fully utilized. The average Beta index obtained in the study area was 1.1. This average value of 1.1 depicts that in terms of Beta index, the road network in Akure metropolis is generally well connected. The Gamma index across the TAZs ranged from a minimum of 0.3 to a maximum of 0.5 while the average Gamma index was 0.4, which implied that more road segments can still be accommodated in road network of the study area to enhance transportation of residents. Analysis of traffic data showed that 61% of the traffic composition in the study area were passenger cars, while motorcycles accounted for 34% of the traffic composition and Vans, Trucks, Lorries and Buses accounted for 1%, 2%, 1% and 1% respectively. The traffic density ranged from 100 pcu/km to 320 pcu/km while the traffic volumeranged from 524 pcu/hr to 3766 pcu/hr across the zones. LOS values ranged from 0.19 to 0.93 across the zones. Furthermore, it was discovered that that the Shoprite/Parliament TAZ with an LOS of 0.93 had the worst traffic quality as it was Type E, an indication of unstable flow. The Erekesan -Erekefa and Idiagba-Ijemikin TAZ had the next highest LOS of type D with values of 0.86 and 0.89 respectively. Results of statistical analysis carried out to determine the relationship between the road network connectivity indices and LOS showed that Alpha, Beta, Gamma indices with Pearson correlation coefficients of -0.066, -0.152 and -0.179 had no statistically significant relationship with LOS. The study recommends the implementation of the results of the study to government and transportation agencies so as to forestall the occurrence of unfavourable traffic conditions in the road network of the study area.