# The the through movement is the proper delay to

Theexperiencing of delays on the arterial signalized roads are mainly related tothe intersections where conflicting movements are separated and controlled bytraffic signals. The traffic signals can operate under an isolated controlstrategy, with the signal settings of each signal set independently of thesettings of adjacent signals. The delay is defined as the difference in traveltime when a vehicle is affected and unaffected by the controlled intersection.This delay contains lost time due to deceleration and acceleration as well asstopped delay. Thus, intersection delay estimates are directed towardestimating total delay or simply stopped delay 7.Thecontrol delay for the through movement is the proper delay to use in an urban streetassessment.

Equation (1) is used to compute the control delay. Equations(2) and (3) are used to compute the uniform delay and incrementaldelay, respectively HCM, 2000: Where,  (1)  (2)  (3)  d= control delay (sec/veh);d1= uniform delay (sec/veh);d2= incremental delay (sec/veh);d3= initial queue delay (sec/veh);PF= progression adjustment factor;X= ratio of v/c for the lane group (also termed Saturation degree);C= cycle length (sec);c= capacity of lane group (veh/hr);g= effective green time for lane group (sec);T= duration of analysis interval (hr);k= adjustment for incremental delay for the actuated control; andI= adjustment of incremental delay for the filtering or metering by upstreamSignals. 1.   Study AreaThe study area lies in the capital Baghdad in “Al-Karkh”.

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Fig. (2) illustrates the study area and the main details using GOOGLEMAPS. It represents Al-Mansour intersection along 14th-RamadhanStreet.    Fig. (2)Satellite image of the study area2.   Collecting of Traffic Data Toevaluate the traffic operation performance of the intersection, field data containingvolumes of the traffic should be gathered. Data collecting are gatheredmanually by many observers during the days of work, where the largestcongestion, as well as; inadequate use of transportation take place at hours wherethe flow is high.Thetraffic volume data were collected for two months within different daysdistributed on three times per day for the intersection (7:00 – 9:00 A.

M),(1:00 – 3:00 P.M) and (5:00 – 7:00 P.M) as shown in Table. (1). Also, suddenlyinterviews are considered with interested people like traffic policemen at the areaof study and different users of the road to help in selection the peak hourperiod for traffic data collection. It is well known in most of traffic studiesfor evaluating and enhancement of the existing intersection, the following dataas shown in Tables (1), (2) and (3) are needed:v V(veh/hrs.): Demand volume by movementv PHF:Peak-hour factor v Hv(%): Percent heavy vehiclesAllvehicles are divided into small size which any of them moves on four tirescontains passenger cars. Also, Large size which any of them moves on more thanfour tires.

Table (1) Traffic Data Collected From Al-Mansour Street From Al-Mansour Street A.M P.M 7:00-8:00 8:00-9:00 1:00-2:00   2:00-300   5:00-6:00 6:00-7:00 R (pcph) 76 92 127 100 52 70 RHv (vph) 5 3 0 0 0 0 RHv (%) 6.173 3.158 0 0 0 0 PHF 0.808 0.735 0.

756 0.807 0.500 0.670 L (pcph) 78 44 96 83 170 291 LHv (vph) 6 0 0 0 3 0 LHv (%) 7.143 0 0 0 1.734 0 PHF 0.750 0.

794 0.750 0.769 0.

796 0.700    Table (2) Traffic Data Collected From Al-Yarmuk Intersection From AL-Yarmuk Int. A.M P.M 7:00-8:00 8:00-9:00 1:00-2:00   2:00-300   5:00-6:00 6:00-7:00 R (pcph) 161 122 141 191 293 586 RHv (vph) 0 0 0 0 0 0 RHv (%) 0 0 0 0 0 0 PHF 0.660 0.782 0.690 0.

770 0.49 0.870 TH (pcph) 174 102 180 158 316 426 THHv (vph) 0 0 0 0 0 0 THHv (%) 0 0 0 0 0 0 PHF 0.

790 0.670 0.738 0.580 0.

850 0.840  Table (3) Traffic Data Collected From 14th-Ramadhan Intersection From 14th-Ramadhan Int. A.M P.M 7:00-8:00 8:00-9:00 1:00-2:00   2:00-300   5:00-6:00 6:00-7:00 TH (pcph) 59 83 124 89 123 287 THHv (vph) 4 2 0 0 0 0 THHv (%) 7.018 2.353 0 0 0 0 PHF 0.641 0.

694 0.775 0.670 0.702 0.740 L (pcph) 24 58 59 67 459 606 LHv (vph) 0 0 0 0 0 0 LHv (%) 0 0 0 0 0 0 PHF 0.461 0.604 0.

702 0.670 0.755 0.

860   3.   Analysis and ResultsAn excel sheet is prepared for analyzing the data as shown in Table(1) previously to appoint the peak hour. From the traffic account in thefield survey, (6:00 – 7:00 P.M) were concluded as the peak hour at theintersection. Summation of the traffic flows during this hour were 2166 vph asshown in Fig.

(4).5.1           Evaluation of Existing LOSThe traffic data of existing intersection is evaluated using theHCS software as shown in Fig. (4), where the signals are actuated on3-phases. It gives the level of service F as shown in Table (4).

Thegeometric layout using AutoCAD software is as shown in Fig. (5). Fig. (3) Traffic Data of Al-Mansour Intersection  Fig. (4) Operation Analysis of Existing LOSTable (4) Intersection Delay of Existing LOS    Fig.

(5) Geometric Layout of Existing LOS and 1stProposal  5.2           Proposal Design Alternatives5.2.1   Design of Traffic Signal TimingTwo proposals of traffic signal timing were suggested: The firstproposal is to optimize the existing data using HCS software as shown in Fig.(7), where the signals are actuated on 3-phases.

It gives the level ofservice “D” as shown in Table (5). The geometric layout is asshown as in Fig. (5), previously. So, the carry out of this alternativewill give a little enhancement on the LOS, so; the second proposal was suggested.  Fig. (7) Operation Analysis of the 1st proposalTable (5) Intersection Delay and LOS of the 1st Proposal  The second proposal of enhancing the traffic operation of intersectionis as shown in Fig.

(8), 3-phases are actuated with an exclusive rightlanes for the vehicles travelling from Al-Yarmuk and Al-Mansour approaches.After analyzing the traffic data, it was conclude that the carry out of this alternativewill enhance the level of service to “C” as shown in Table (6).The geometric layout is as shown in Fig. (9). This proposal is good forexecution but for more enhancing of the traffic operation, another twoproposals were suggested later, relating with the re-design of the geometricfeatures of the intersection in addition to the traffic signal timing.