Abstract:
Slower vehicles can be passed only in the lane normally used by vehicles travelling in the
opposite direction. Passing demand increases rapidly as traffic volumes increases, while
passing opportunities in the opposite lane decline as the opposing volume increases. This
results in the formation of platoons of vehicles in which drivers are subject to delay
because of the inability to pass. Delay affects trade performance of a country in terms of
cost, time, reliability, predictability and customer services.
The research study was focused on to investigate the causes of traffic delay at Adama to
Wolenchity road segment. The methodology that has been employed for the study was a
quantitative descriptive research design method. The data needed were; traffic volume
data, spot speed data, travel time data, road condition data and survey questionnaire data
depends on deriver provider’s response. The traffic volume data was collected by using
video camera for 12 hours starting from 6:00 AM to 6:00 PM at 15 minutes interval on
Monday and Thursday, Spot speed data collection method was elevated video camera for
1 hour on 54m strip at Thursday daylight and travel time data was collected again by
camera, Thursday at 1:00 pm - 2:00 pm with 200m distance measured by tape. Geometric
layout data was measured by tape and questionnaire was distributed to drivers.
The volume of each vehicle category was converted to the same vehicle category using
passengers’ car unit (PCU) of each vehicle class. Data analysis and processing have been
performed using micro soft excel and SPSS (Statistical Package for the Social Sciences)
for spot speed in order to know the causes of traffic delay on segment. The result from
travel time and spot speed has been indicated that the level of service D.
At last, the study identifies, the delay occur due to truck congestion, carts, narrow
Adama-Wolenchity road segment, insufficient road lanes, poor drivers vision for other
drivers, mixed of different traffic, town expansion and road surface problem reason and
recommends shifting of heavy vehicles to other mode like rail way, restriction for heavy
vehicles use expressway, illegal parking, for carts must use lateral clearance and increase
the number of lanes of Adama-Wolenchity road segment. Finally proposed the design
speed should be posted with 52km/hr based on traffic flow
