Evaluation of Effectiveness of Traffic Calming at Roundabouts Within Nifas Silk Lafto Sub City

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Addis Ababa University


Roundabout is a type of intersection that indirectly provides traffic control without the use of traffic signally. Roundabout can provide safety and traffic flow benefits when compared to stop controlled and signal controlled intersections. Road traffic accidents at roundabouts in Addis Ababa have increased over the years. This supported by Nifas Silk Lafto Sub City Traffic Police (2003/06) accident statistics, which shows that 16, 38, 89 and 71 both fatal and non-fatal accidents occurred in the years respectively. This problem will continue and it may more difficult in the future due to the rapid growth of population and vehicle numbers in Addis Ababa Therefore, it is essential to evaluate the effectiveness of roundabout in terms of road users’ safety and general geometric condition of roundabout. The aim of this study to assess and evaluate the effectiveness of traffic calming at roundabout with regard to speed and users safety within Nifas Silk Lafto Sub City. This research examined effectiveness of the four roundabouts (Karl, German, City Tip and Kore). This research achieved by carry out a field survey to assess general geometric condition of roundabouts, a questionnaire to users with regard to safety perception and analyzed the data using SPSS. Spot speeds measuring using Laser technology and calculated using equation of 85th percentile speed. Results indicated that zebra crossing, movement around the roundabout, design of roundabout, sidewalks and guardrails are better safety regarding to pedestrian perception questionnaire. Evaluation of geometric conditions such as geometric configuration, geometry of the elements of a roundabout, pavement marking and pavement condition has a negative influence on driver behavior. In addition, enough confirmation of 85% of the observed vehicles travels at and below entering roundabout such as Karl, German, City Tip and Kore with regard to 46km/h, 54km/h, 65km/h and 55km/h respectively below AACRA speed limit is 60km/h except City Tip roundabout. Therefore, drivers have good driving behavior change due to typically slowdown and good communication with other road users with regard to speed . Keywords :( Roundabout, Effectiveness Perception, Spot speed study and Safety).



Roundabout; Effectiveness Perception; Spot speed study and Safety