International Journal of Traffic and Transportation Engineering 2012, 1(1): 1-6 DOI: 10.5923/j.ijtte.20120101.01 Utilizing Vissim to Evaluate Ramp Metering Performance Akmal Abdelfatah 1,* , Ahmed Ramadan 2 , Gamal Darwish 3 1 Civil Engineering Department, American University of Sharjah, P.O. Box 26666, Sharjah, United Arab Emirates 2 EMAAR,The Economic City, Jeddah, KSA 3 Civil Engineering Department, Cairo University, Giza, Egypt Abstract This paper provides an example of using microsimulation tools to examine the impact of using ramp meter- ing on freeway performance. The well-known software package VISSIM has been utilized in this work to determine the effect of various parameters, such as volumes to capacity (v/c) ratio, detector location on the freeway, and the green times on ramp metering performance. The test network for this research is a microsimulation model for apart of Emirates Road, which is one of the major freeways in Dubai, United Arab Emirates (UAE). The basic model information was exported from the Dubai Strategic Planning Model R1000 (using VISUM software) to VISSIM (microsimulation software). The traffic conditions considered two different downstream conditions (with and without downstream bottleneck). The results showed that the application of ramp metering has a significant positive effect on freeway performance, when the traffic volume levels are moderate to high. On the other hand, the ramp metering application showed a slight improvement under low or very heavy traffic volumes. Keywords Ramp Metering, Microsimulation, Freeway Management 1. Introduction Ramp metering has been proven to be one of the effective freeway management strategies as it can improve freeway performance. Therefore, many cities in North America and European countries have applied ramp metering to some of the major freeways. In some cases, ramp metering may re- sult in deterioration in the freeway and/or the ramp per- formance; therefore, it should be applied carefully. None of the cities in UAE has any freeways that are equipped with ramp metering. This research provides an initial study on the level of effectiveness of ramp metering on freeways inside Dubai, UAE. 2. Literature Review Ramp metering has several control strategies that were considered by different researchers. This section provides a brief description of the control strategy used in this research (the ALINEA control strategy) and discusses the different simulation models that have been used to test ramp metering strategies. 2.1. Alinea Control Strategy Papageorgiou et. al.[1-3] developed the ALINEA (Asser- * Corresponding author: akmal@aus.edu (Akmal Abdelfatah) Published online at http://journal.sapub.org/ijtte Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved vissementLINe´aired'Entre´eAutoroutie) control strategy, which is one of the most common strategies for ramp me- tering operations. The ALINEA strategy is activated at each time interval T, which is usually between 20 to 60 seconds. At the end of each interval, the ramp flow for the next time interval is calculated through the measured volume and occupancy on the downstream of the ramp. The ramp me- tering flow equation shows that, the value of the ramp flow is independent of the upstream flow q in , which is not explicitly used in the strategy. Figure 1 shows a schematic representa- tion of the ALINEA strategy. As the main goal of ALINEA is to maximize the down- stream flow q out , the set value (desired occupancy) Ô should be set equal to the critical occupancy (O cr ), which should be known before ALINEA can be applied to this end. The O cr value can be determined either visually from the a (q out ; O out )-diagram, but, in that case O cr will be a constant value, or by designing a method for maximizing the freeway flow q out without having to rely on constant pre-specified set values O cr [1- 3]. Figure 1. Illustration of ALINEA strategy[1] q out Q out q in Q in Merge Segment r(k)= r(k-1) + K R [Ô – o out (k-1)]