College of Engineering

A master thesis was discussed in department of Civil Engineering / College of Engineering at University of Mosul entitled “Evaluation of Traffic Operation and Geometric Principles of Roundabouts” submitted by the student ( Iman Hasan Mohammed Hasan ) on Monday March 03, 2025 .

The main objective of this work is the assessment and evaluation of the capacity, delay and LOS of main roundabouts of both sides of Mosul city using HCM6.0 models, SIDRA INTERSECTION8.0 software, and RODEL software for both exit and future conditions. In addition, to estimate the entry capacity of main roundabouts using other methodologies. Such as Kimber model, Swiss model, German model. Comparing the capacity estimation of different methods to the actual capacity values using statistical analysis to choose the best method that can present the capacity condition in Mosul.  Developing a special model for roundabout capacity in Mosul city that relate driver behavior and traffic flow. Studying the effects of geometric elements and flow traffic on roundabout capacity in Mosul city.  Improving the capacity, delay and LOS conditions for roundabouts in both sides of Mosul city for exit and future conditions.

The study seeks to estimate the entry capacity and evaluate of the performance of roundabouts in Mosul city Iraq, as the  selected roundabouts exposed to high traffic volume and congestion during peak hours. The estimation of capacity is a significant problem. as many models and software programs are developed for the capacity estimation, selecting a best method that presents the actual case is essential.
The Study Results :
The statistical analysis showed that SIDRA Software, RODEL Software, and HCM models were the most effective in presenting the capacity, respectively.
The work includes studying the influence of the geometrical elements on the entry capacity using RODEL software. The study shows that there is a direct correlation between entry capacity and geometrical parameters of roundabout and the entry capacity of roundabout affected mostly by the approach half width where the correlation between entry capacity and approach half width showed a value of R2 =0.74.
The Study focused on developing a model for roundabout entry capacity estimation in Mosul using the critical gap and follow up headway measured directly from the field. The model calibrated and show that it is acceptable with R2 =0.9496 and SE=19.97.
The improvement included to enhance the LOS of the exist and Future conditions include increasing the width of an approach, the entry width, and inscribed circle diameter so that all roundabouts can operate on the LOS C, or D.