85Th Percentile Speed Prediction Model For Bode Saadu– Jebba Road In Kwara State, Nigeria

• Main Authors: O. O. Joseph, A. I.Dauda
• Format: Article
• Language: English
• Published: Eastern Macedonia and Thrace Institute of Technology 2014-01-01
• Series: Journal of Engineering Science and Technology Review
• Subjects: polymer electroluminescent devices; energy level measurement; interface optimization
• Online Access: http://www.jestr.org/downloads/volume4/fulltext152011.pdf

Among the roadway element, horizontal alignment has long been recognized as having a significant effect on vehicle speeds. Unexpectedly tight horizontal curves can lead to accidents as drivers try to negotiate them at too high a speed. Design features, such as curvature and super elevation, are directly related to, and vary appreciably with design speed; while the 85%percentile speed of light vehicle is commonly used as a basis for the design i.e. the speed exceeded by only 15% of the vehicles. Reconnaissance survey of the area was carried out; geometric data were extracted from the working drawing while instantaneous speed were measured manually using stop watch at selected locations. Regression analysis of both the geometric data extracted and the 85th percentile speed evaluated were performed using Statistical Package for Social Sciences (SPSS to formulate simple mathematical model for operating speed. The coefficient of determination(R) and coefficient of determination (R2) obtained were 85.2% and 72.6% respectively.In the reported model for 85th percentile vehicular speed, regression parameters were statistically significant for variables, the relationship exists between all the parameters since the both output shows R – sq value was more than 50%. It can be conclude that, the operating speed of the vehicle depends on the Radius (R); Length of curve (Lc); Tangent lengths (TL ); Gradient (G); and Super elevation (e). It is recommended that the model equation obtained could be used to obtained design speed in the study location and similar road network; while a large national research effort aimed at developing speed models for Nigerian situation should be conducted, the results will aid in the development of consistent design and traffic control