Analysis of Traffic Operation for AL-Kafa’at Signalized Intersection in Al-Kut City

Traffic Studies Aim (Traffic analysis) to estimate some of the important indicators to determine the level of service (LOS) at intersections in the cities. That's where the increase in traffic volumes at intersections is one of the main problems that makes the traffic difficult in these intersections and which raises congestion in these areas. The objective of this research is to evaluate the operational capacity of intersection (AL-Kafa’at) in AL-Kut city and show better proposals to improve the performance in terms of capacity. To achieve these objectives traffic information has been collected using digital camera to various directions for the purposes of analysis and traffic engineering while HCS traffic program is used for the purposes of traffic analysis process. The operational analysis of the existing conditions of this intersection indicates that the LOS is ( F ) with an intersection delay value of 105.1 sec. /vehicle .Because of the reasons above, it is important to enhance the performance of AL-Kafa’at Intersection by increasing the number of lanes to the right turn for Alhaidariya Approach. The results indicate that the intersection LOS is hanged to ( D ) with a cycle time of 91 sec. and an intersection delay of 38.1 sec. /vehicle.


INTRODUCTION
ransportation Engineering is the application of technology and scientific principles to the planning, functional design, operation, and management of facilities for any mode of transportation in order to provide safe, rapid, comfortable, convenient, economical, and environmentally compatible movement of people and goods.
Traffic engineering is that phase of transportation engineering which deals with the planning, geometric design and traffic operation of road, street, and high-ways, their network, terminals, abutting lands, and relationships with other modes of transportation [1].
An intersection is defined as the general area where two or more highways join or cross, including the roadway and roadside facilities for traffic movements within the area.Intersections are an important part of a highway facility because, to a great extent, the efficiency, safety, speed, cost of operation, and capacity of the facility depends on their design.Each intersection involves through-or cross-traffic movements on one or more of the highways and may involve turning movements between these highways.Such movements may be facilitated by various geometric design and traffic control, depending on the type of intersection [2].
The concepts of capacity, level of service and delay are central to the analysis of intersections, as they are for all types of facilities, therefore that both capacity and level of service must be fully considered to evaluate the overall traffic operation of the intersections [3].While the delay is one of problems that occurs in any facility of traffic.AL-Kafa'at intersection in AL-Kut city is an important congested intersection due to its critical location on major streets.This intersection has the following characteristics: 1.It has a very high traffic volume in two approaches.2. It is located on Major Street which intersects with two minor streets.3.Many activities are located around this intersection.

Study Area
AL-Kafa'at signalized intersection is one the most important intersections located in the center of AL-KUT city, AL-Kafa'at signalized intersection consists of three major streets: 1. Baghdad Street 2. AL-Kafa'at Street 3. Alhaidariya Street AL-Kafa'at signalized intersection is a significant location and a highly volume.This can be related to: 1. AL-Kafa'at signalized intersection is located in an important location.It connects between main directions from AL-Kafa'at Street toward Alhaidariya Street.2. The existing of different public activities near AL-Kafa'at signalized intersection.These activities resulted in a high traffic volume and lead to create a high delay especially at peak hour.

Figure (1): Satellite Image for AL-Kafa'at Signalized Intersection in AL -KUT City Objectives of the Study
The main objectives of this study are: 1.
Specify the peak hour volume and calculate the peak hour factor (PHF) for all approaches at AL-Kafa'at signalized intersection.

2.
Evaluate the existing level of service (LOS) at the studied intersection.

3.
Evaluate all proposals, calculate the level of service for each proposal and select the best proposal that can solve the congestion problem and provide a good performance within the design period.

Data Collection: Traffic volume
To determine the existing traffic volumes; a digital camera is used at AL-Kafa'at signalized intersection from (7:00 a.m up to5:00 p.m) during the workdays of the week from (22 February to 27 February) 2014.This survey aims to find the peak hour volume, which represents the design hourly volume.The type of vehicles are classified into two types, they are:

•
Passenger car: all vehicles, which have four tires only.

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Heavy vehicles: all vehicles, which have more than four tires.The heavy vehicles were converted to passenger car by using a passenger car factor equal to (2.0) [3].
The volume for peak hour represents the design hour volume, which will be used in the analysis of this study.Table (1) shows the traffic account at nestle intersection for 15 min period from 7:00 a.m -5:00 p.m.While Table (2) shows the total volume for all approaches each 15 min.

Saturation Flow
Calculation of saturation flow rate depends on the headway data collected for queue vehicles at stop line for each approach at the time of departure on green time.Saturation flow represents one of the main parameters in which has a major effect in the capacity of intersection [4].The existing saturation flow is calculated by using HCS Software.Table (3) shows the calculated saturation flow at the stop line for all approaches in AL-Kafa'at signalized intersection by using HCS Software.

Existing Geometric Design
To evaluate the level of service at nestle intersection it is very important to specify the number of lanes for each approach .The existing geometric layout for AL-Kafa'at intersection and its approach is show in Figure (2).

Analysis and Results:
Peak Hour Volume By using Excel program, the traffic account shown in Table (1) was analyzed to specify the peak hour.From site investigation and traffic account, the following conclusions were observed: a.
It was found that the peak hour is limited between 12:00 P.M and 1:00 P.M.The total volume during this hour is (1691) pc/h.b.
The maximum traffic volume is concentrated in the approach coming from the Alhaidariya Street.This volume is (751) pc/h.while the lowest volume is (345) pc/h comes from Baghdad Street c.
The percentage of heavy vehicles for all approaches in AL-Kafa'at signalized intersection is a shown in Table (4).d.
The variation of traffic volume for each approach is shown in   The peak factor is defined as the ratio of total hourly volume to the maximum 15min rate of flow within the hour.
The peak hour factor is calculated for each direction in AL-Kafa'at intersection using the data mentioned in

Existing Los at AL-Kafa'at Signalized Intersection
The operational of the existing geometrical features and traffic volumes of AL-Kafa'at intersection is performed by using HCS 2000 .Table (6) illustrates the result of analysis.The result indicates that the intersection LOS is (F) with an average intersection delay of 105.1 sec/vehicle.Therefore, the enhancements are required to reduce the intersection delay and change the LOS.In order to improve the traffic performance in the study area, improvement proposals will be explained in the following section.

Proposal No. 1: Increasing number of lanes in one direction:
In this proposal, changing of geometric design for the intersection by increasing the number of lanes in one approach for Alhaidariya is suggested to right turn.It was found that the LOS of the intersection became D with an overall delay of (38.1) sec/veh.From the result, it is noticed that the (LOS) for the intersection is (E) Therefore, the proposal is not good enough for the intersection.Table (8) shows the results for this proposal for the cycle time 98.1 sec.as an example.The results are based on existing traffic volume observed at the selected signalized intersection.The operational analysis of the existing conditions of this intersection by the Highway Capacity Software (HCS2000) indicates that the LOS equal to (F) with an intersection delay value of 102.8 sec./vehicle.Therefore, and because of the reasons above, two enhancement proposals were suggested.The study showed that increasing number of lanes to the right turn for Alhaidariya approach is the best solution to enhance the intersection performance.
Figure (1) shows a satellite image for AL-Kafa'at signalized T intersection and the boundary of the study area (directorate of statistics in the AL-KUT city, 2010).
Figure (3) for 15 min interval while Figure (4) shows the total volume at the intersection for each (15) min.

Figure
Figure (2): Existing Geometric Design for All Approaches in AL-Kafa'atSignalized Intersection

Table ( 7): Expected Level of Service at AL-Kafa'at Signalized Intersection with
Table (7) shows the result this proposal No.1

changing the cycle length for the intersection
In this proposal, several cycle lengths are examined by using HCS program.

Table ( 8): Expected Level of Service at AL-Kafa'at Signalized Intersection with
Kafa'at signalized intersection is one of the most important intersections in AL-kut city, and serves about 8000000 passages of vehicles yearly.