Actuated Signal Control

Transcription

1 1 Disclaimer: The objective of the tutorial is not to create an expert in VISSIM modeling but to get a new user sufficiently (and quickly) up to speed so they can use the manual and other resources when they have questions on model development. That is, helping a new user past the frustrating which button do I press part of the learning curve. These tutorials should not be considered as official methods or guidance in any way. It is certainly possible other modeling experts may disagree with portions of the tutorial or there is an outright error in the tutorial. However, it is hoped, the tutorials provide a good start on the process of model development. If you find any errors or issues please feel free to let us know at michael.hunter@ce.gatech.edu so we can update the material. Actuated Signal Control This tutorial demonstrates how to use detectors in VISSIM to create semi-actuated and fully actuated intersections. After completing the 3 intersection tutorial, you have this network backbone (Fig. 1). Figure 1. Existing network layout. The controller that will be used to replace the fixed time signal control is called a Ring Barrier Controller (RBC) which uses the Dual Ring logic. For this purpose, you need to define the signal groups for each turning movement. The following will be used: 1. Renaming Signal Controllers The signal controllers will be renumbered and a third controller will need to be created. - From the main menu, click Signal Control > Edit Controllers (Fig. 2). Select the 111 Side Cross Rd o Change the No. to 1. o Change Name to Intersection 1 o For Type, make sure Ring Barrier Controller is selected. - Click on the 222 Mid. Cross Rd controller, o Change the No. to 2. o Change Name to Intersection 2 o For Type select Ring Barrier Controller. - Now select ect Intersection 1 and click Edit Signal Groups. A new window will pop up.

2 2 Figure 2. Signal control dialogue. 2. RBC Parameters The tree on the left contains the settings you will use for the actuated controller. Clicking on the + or expands or collapses different options, and checking and un-checking the boxes will show or hide the settings on the right side. Initially, we are going to set up the 3 intersections to operate in free running mode with actuation on the side streets. 2.1 Intersection 1 - The following parameters should be entered under the Basic timing options: SG Number Min Green Veh Extension 3 3 Max Yellow Red Clear Start Up Min Recall Max Recall Dual Entry Under Base Timing-> Pattern Schedule, make sure it is set on Free with a start time of 0. Under Detectors-> Vehicle, the following should be entered: Detector Number 4 8 Call 4 8 Extend SG Leave the Detector Mode in No Disconnect

3 3 The controller frequency, located in the top right corner, should be set to 2. This determines how many times per second the RBC controller communicates with VISSIM during the simulation. The simulation resolution must be a multiple of the controller frequency. If not an error message will appear. Setting the frequency to 2 allows you to use fraction of a second values (for vehicle extension or yellow time) because the controller will communicate twice with VISSIM each second. The RBC Controller for Intersection 1 is shown in Fig. 3 on the next page. Figure 3. RBC Controller setting for Intersection 1.

4 4 When you click OK, it will prompt you to save the RBC file. Save it in the same folder you ve been working in as RBC 1 and click OK. 2.2 Intersection 2 - The same process needs to be repeated. - Click on Intersection 2, and then Edit Signal Groups. - Change the minimum and maximum greens, vehicle extensions, min and max recall, etc. to match Fig. 4 on the next page. Figure 4. RBC Controller setting for Intersection 2. Enter the information exactly as it is shown above. Choose File -> Save As and then save the file as RBC 2 before you click OK.

5 5 2.3 Intersection 3 This intersection will have the exact same timings as the first controller. From the Signal Control -> Edit Signal Controllers window, click on Intersection 1, right click and copy. Rename it as No. 3 and Intersection 3. Now click Edit Signal Groups. In order to give Intersections 1 and 3 different offsets later when we coordinate, click File, Save File as and enter RBC 3. All signal timing information has been entered for free running operation, now the signals must be redefined and detectors placed. 3. Modifying Signal Heads All of the existing signal heads should have remained in place, however if one has been deleted just create a new one. Make sure the signal group phases are correct. To do this, go to View -> Network Elements. Check the Show Element box for Signal Heads, and under Label, select Signal Group No. The signal group phase numbers should match Fig. 5 below. To edit signal heads, click, click once on the link, then double click on the stop bar (or right click off the network). Intersection 1 All signal heads should have 1 chosen as the SC No. Intersection 2 All signals should have SC No. 2. Intersection 3 Make sure all SC No. are changed to 3. Intersections 1, 3 Intersection 2 Figure 5. Signal group numbers for the side and middle intersections. Figure 6. Detector dialogue box. All signal heads must be changed to the correct SC and Signal groups as shown above in Fig Installing Detectors While placing detectors, it s helpful to see where the stop bars are. To turn them on, go to View > Network Elements. Check the Show Element box for both Detector and Signal Head, (you can change the signal head label to None), then click OK. - Click the Detectors icon on the left toolbar and left click on the southbound link north of Intersection 1. Right click before the stop bar and the Detector dialogue box will appear (Fig. 6). **(Note: If you click too close to the stop bar, there won t be enough room to place detector). Set the detector No. to 4 (corresponding to SB through) Set the length at 50 ft (15.24 m) SC: 1 (for Intersection 1) Type: Presence (use this type for all stop bar detectors)

6 6 - Click OK. To move the detector click once on the link, and then click and drag the loop so that it s just behind the stop bar. Next, place a Presence detector on the Northbound lane with the same attributes, except this time No. 8. Figure 7 shows the detector layout of Intersection 1. Figure 7. Detector Layout for Intersections 1 and 3. Detectors are numbered to define which loops are calling which phases. It s easiest to remember if you number the detectors to go along with the phase it calls. You can have multiple detectors with the same number (multi-lane approach). In this case, a call on one detector is a call on the entire group. For the middle intersection, (SC = 2), we want stop bar detectors (50 ft) on the side streets, and on the EB and WB left turn lanes. In addition, small upstream loops (length of 6 ft) will be placed approximately 200 feet before the intersection in both lanes (just upstream of the turn bays). The upstream loop numbers will have the following properties: No = 2 for Eastbound and 6 for Westbound. Set the length at 6 ft (1.829 m) SC: 2 (for Intersection 2) Type: Pulse Figure 8. Detector Layout for Intersection 2 (Middle Intersection).

7 7 Number the detectors corresponding to their phase numbers shown in Fig. 8 above, with SC = 2. Intersection 3 will be identical to 1, except with SC = 3. Save changes and run the simulation. Notice in the free running mode the cycle length varies and vehicles aren t able to drive all the way through without stopping. NOTE: If you are getting an error reguarding the simulation resolution, from the top menu: Simulation -> Parameters -> change the Simulation Resolution to 2 5. Signal Coordination Coordination is defined by patterns in the RBC Controller. There are 8 different patterns and that can be defined to work during different times of the simulation run under pattern schedule. If an option (such as max recall) exists in both the Base Timing menu and the Pattern menu, then whatever is entered in the Pattern window will overwrite the previous properties. However, if a box is checked under the Base Timing drop down, then it cannot be unchecked for the pattern. 5.1 Intersection 1 Signal Control > Edit Controllers > Edit Signal Groups for Intersection 1. - Enter the Splits and Min Green as shown below, and then check 2 and 6 as the coordinated phase. - The Global Pattern properties are shown on the bottom left side (Clicking + to expand). Set the cycle length to 90 seconds with an offset of 0 seconds and change to MaxInhibit (Fig. 9). Leave all other settings at default. - For the Pattern Schedule, add Pattern 1 and set the start time to 1800 seconds. This will cause free operation until 1800 seconds, and then coordination will begin. Figure 9. Pattern 1 details for RBC 1.

8 8 5.2 Intersection 2 Enter the values below for Intersection 2. Figure 10. Intersection 2 Pattern for RBC controller. Intersection 2 offset is 15 seconds, and the MaxGreenMode should be MaxInhibit 5.3 Intersection 3 Same as Intersection 1, except change the offset to 30 seconds. 6. Protected and Permitted Left Turns - There are two ways to allow protected and permitted left turns. 1. The first (and easiest way) is to modify the signal head by checking the Or Sig. Gr box, then select Phase 2 to go along with phase 5 left turn, and Phase 6 to go with the Phase 1 left turn. 2. The second method is to create an overlap phase. In the overlap section of the RBC controller, create a new overlap signal group (#12 for example). Set the yellow and red clearance and for Parent, select the two phases you want to overlap (1,6). o Create another overlap (SG 13) with parent phases 2,5. - Modify the signal head so that the left turns are now numbered 12 and 13.