## 3 Data Collection and Preparation
### Data Collection  
Geometric data for the area was available from the Ministry of Transport as well as from shop drawings, Google Maps, and survey work. Field visits were required to verify this data. Figure 2 describes the layout of the study area. The geometric details are summarized in Table 1. A single-point urban interchange is also taken into account in the data collection because all vehicles entering the highway come from it.  
According to the traffic data for the site that was collected by ADA in 2015, the peak hours were divided into three time periods: A.M. peak (07:45-09:00) with maximum volume of 7707 veh/h, mid-day peak (12:15-13:45) with 7363 veh/h, and P.M. peak (16:00-17:00) with 7106 veh/h.  
Based on this information, this study concentrated on A.M. peak. The vehicle counting started at 6:30 A.M. and ended at 10:00 A.M. As well, it was repeated from 14:45 to 17:30. Per the study, vehicle movements were recorded for two days (4 October 2017 and 9 October 2017). In the first survey, the A.M. peak was 08:00-09:00 with the volume of 7969 veh/h and the P.M. peak hour was 15:15-16:15  
Figure 1: Aerial photo of the study area.  
with 6887 veh/h. However, in the second survey, the A.M. peak hour slightly shifted to 07:00-08:00 with 8005 veh/h and P.M. peak hour was the same as the first survey with 7027 veh/h. Ultimately, the A.M. peak hour was chosen as 07:00-08:00 with 8005 veh/h to deal with the worse-case scenario.  
The peak hour factor (PHF) was calculated as 0.97, which reflects that the volumes in the area do not fluctuate much throughout the peak hour. Figure 3 shows the traffic volumes during the peak hour and that the three movements coming from the nearby interchange account for the volume of 3131 veh/h. Also, it may be noted that 2588 veh/h of high traffic volume enter the freeway using the on-ramp, which is the main target of this study. From capacity analysis, this weaving area was proved to have the LOS F.  
According to the FWHA (Federal Highway Administration) vehicle classification, the vehicle compositions in the study area are: 99.25% of class 2 (passenger car) and class 3 (SUV and small buses);  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Location** & **Number of Lanes** & **Width (m)** & **Length (m)** & **Gradient (\%)** \\ \hline Main Freeway & 3 & 10.8 & 1130 & \(-\)2\(\rightarrow\)+2 \\ \hline On Ramp & 2 & 5.6 & 145 & \(-\)2.0 \\ \hline Off Ramp & 2 & 5.6 & 130 & +2.0 \\ \hline Frontage Road & 3 & 9.5 & 790 & 0\(\rightarrow\)1 \\ \hline Auxiliary Lane & 2 & 5.5 & 195 & 0\(\rightarrow\)1 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Summary of study area geometry.  
Figure 3: Summary of traffic volume during peak hour.  
Figure 2: Geometric drawing of the study area.  
0.55% of class 4 (buses); and 0.2% of class 5 (single unit track). No other vehicle types are allowed to enter the freeway during peak hours [24].  
Travel speed of a vehicle is one of the most important measures to describe the given state of traffic flow. The speed limit of the freeway section in the study area is 100 km/h. In this study, two types of speed were used. The time mean speed from 182 random samples for the A.M. peak hour was 84.16 km/h. This was used as the desired speed required in VISSIM as an input. The space mean speed was calculated from the field data which was captured from the recorded video using two parallel and 37 m apart imaginary lines. It was used as a measure of effectiveness in the VISSIM simulation process.