Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Signalized intersection

Evaluating and Improving the Efficiency of Intersection of Freeway Off-Ramps with Arterial Roadway

Atheer N. Hameed

Engineering and Technology Journal, 2013, Volume 31, Issue 21, Pages 28-37

The signalized intersections are considering one of the critical elements in facility work of urban arterial roads. Thus, it is necessary to improve the signalized intersections system not only to increase the ability of flow on the major and minor roads but also to increase the neighboring freeways ability to work with high efficiency.
In the 4-leg signalized intersections, left-turn effect greatly on the capacity, if left-turn movements eliminated by converting it to right and through, so that, the signal can operate with only two phases instead of four phases and capacity will increase. The objective of this study was to evaluate the influence of eliminating left-turn movements (converting it to through and right movements) on the level of service for an intersection of freeway off-ramps with arterial roadway (figure. 1), in order to decrease the congestion on the oversaturated off-ramps, which affect the traffic flow on freeway. Also studying the influence of this elimination and converting on: (1) average system delay, (2) fuel consumption, (3) average travel time, (4) average delay on freeway off-ramps and (5) average queues lengths on freeway. This elimination and converting will be carried out by constructing two roundabouts (nearby to the intersection) on arterial roadway Figures. (5 & 6). Full-movement signalized intersection with two roundabouts were compared before and after elimination left-turn movements through simulation with the use of the Synchro 6 simulation package. The results showed a significant improvement in level of service for the studied intersection. In addition, significant decrease in average delay and average travel time, and minor decrease in fuel consumption. The results also showed a significant decrease in average delay on freeway off-ramps and queues lengths on freeway.

Evaluation The Performance of Al-Thawra At-Grade Intersection Using The HCS2000 Computer Package

Ali Majeed K.Al-Ubadiy; Zeena Tariq Al-Azzawi; Nawal Dawood S

Engineering and Technology Journal, 2010, Volume 28, Issue 15, Pages 5088-5101

Al-Thawra signalized intersection is one of the most important intersections in AL-Hilla city because it relates the Governorates: Baghdad, Najaf, Kerbala and Babel, and serves of about 21000000 passages of vehicles yearly. The excessive traffic volumes, during the peak periods (at morning and evening), of vehicles that entering the
intersection increase traffic density, reduce travel speed, increase travel time, and increase the delay values. The delay values are reflected by McTrans Center, University of Florida {Highway Capacity Manual (HCM2000)} to an indicator named LEVEL OF SERVICE (LOS). The operational analysis of the existing conditions of this intersection
by the Highway Capacity Software (HCS2000) indicates that the LOS of it equal to (F) with an intersection delay value of 263.7 sec./vehicle and a degree of saturation exceeds 1.5. Therefore, and because of the reasons above, it is important to improve the performance of Al-Thawra Intersection by separate the conflicting traffic movements
with an overpass bridge. The traffic survey shows that the high traffic volume of through movement of the North-South direction (Baghdad-60St.) has the major effect on the intersection. Therefore, the North-South is the suitable direction to construct the suggested bridge overpass to separate the through traffic of this direction (from Baghdad
to Najaf {60 St.} and vice versa) from the other movements of the intersection. The results indicate that the intersection LOS equal (C) with a cycle time of (58) sec. and an intersection delay of (22.8) (sec./veh.) at the object year 2027.