Abstract:
Characteristics of roads have great discrepancy in a regional road network in terms of
pavement dimensions including shoulders and drainage system. The study had attempted to
investigate the effects of rural-urban road characteristics on traffic safety of urban area.
The study identified two roads linking Jimma town. These are sub parts of Jimma to Agaro
road and Jimma to Addis Ababa road. These two roads are characterized by the incidence of
traffic accidents due to increasing number of vehicles, and pedestrian movements. In other
words, there was no adjustment made by the road agency, in which the existing geometry of
the road considered as one factor causing traffic accidents and delays for the road users.
This research has evolved to find the deficiencies of rural-urban roads by comparing the
geometric parameters with ERA manual. The total number of accident of these stretch’s
taken from police record. The values of geometric parameters about these sub-sections are
obtained from asbuilt road design and direct measurement of carriageway width. Finally,
correlation & linear regression analysis is made between the selected geometric parameters
and a total number of accidents. From the selected 5.5 km, the correlation is established in
the form of an equation of a total number of the accident (TA) with a total number of an
accident with carriageway width: TA=173.850 - (15.900 * CW) with Rsqr = 0.918. A total
number of the accident (TA) with a total number of an accident with grade: TA = 48.966 -
(3.607 * G).
The accident black spots were identified and prioritized based on the developed criteria, and
accident rates were calculated. Therefore, it is concluded that the frequency of occurrence of
road traffic accidents and the number of casualties are increasing from time to time in both
stretch of roads & When the carriageway width increases the traffic accident decrease and
the carriageway width decrease the traffic accident increase. Hence, redesigning the road
elements based on the prevailing and future traffic condition is recommended to reduce the
number of road accidents at identified black spots and other sections in the study area.
