Nowadays, traffic congestion, delay and unreliability are terms that are most associated with rnpresent day travel. Transport users expend their precious time on long traffic queues and at thernsame time, fuel emission of vehicles increases in congested traffic conditions. Because of this andrnother problems, late arrival to work places and appointments for social or business activities havernbecome common. And no study has developed a model for estimating travel time and reliabilityrnmodels on arterial roads. In this study a more general travel time and reliability model wasrndeveloped. To study travel time probability distribution and reliability of a road segments in AddisrnAbaba city seven segments are selected. Seven segments were selected for the major modelingrnstudy. Manual method of data collection was used for collecting vehicle travel time and trafficrnvolume data at peak hour for three days. rnTravel time data for two vehicle types were fitted to a probability distribution for each segment.rnReliability of a road segment was analyzed using travel time reliability measures. Multiple linearrnregression models were developed to predict travel time reliability of a road segments. From thernregression analysis all variables were found statistically significant to predict travel timernreliability of a road segment. Traffic volume, segment grade, % of heavy vehicles, number ofrnintersection legs, signal cycle length and segment length are negatively correlated with travel timernreliability of a road segment while average segment width and average speed are correlatedrnpositively. An interaction effect in regression analysis was also developed to study the effects ofrninteraction in regression model. A developed regression model can also be used to identifyingrnthese factors is a key contribution to HCM and AASHTO where studies are being conducted torninclude reliability factors into roadway design features. In addition to this correlation among the rninfluencing factors, this is necessary for traffic operations, traffic design, and long-range rntransportation planning and it explains the contributing impacts of other factors on travel timernreliability improvement on a corridor by modifying one factor.