Go back to: Table of Contents Go to the next lesson Overview : Traffic Analysis Module (TAM) The Traffic Analysis Module (TAM) may be used to evaluate the operational effects of existing and projected future traffic on a highway section and the effects of alternative road improvements such as realignment, cross-sectional improvements, and addition of passing lanes or climbing lanes. For more details, see the Traffic Analysis Module Engineer s Manual. In the work problem, you will use the Traffic Analysis Module to evaluate the operational effects of existing traffic on IHSDM Pike. Work Problem Exercise: - 6.1: Evaluate IHSDM Pike using the TAM 1
Exercise 6.1: Evaluate Existing IHSDM Pike using the TAM I. Create a Traffic Analysis Evaluation 1. If necessary, start IHSDM by double clicking the shortcut icon on your desktop screen, or on ihsdm.exe in the IHSDM software home directory. 2. To view the highways under the IHSDM Pike Project, click on the + sign to the left of the IHSDM Pike node to expand the tree. You should see highway nodes for ihsdm pike and route1 and an intersection node for route1/ihsdm pike. 3. To create an Evaluation for IHSDM Pike: a. Select the highway node corresponding to ihsdm pike by clicking it once. b. Click the New Evaluation button on the Button Panel to bring up the Select an evaluation type window in the desktop area. 2 c. Fill in or select: a. Title: Traffic Analysis 1 b. Comment: Traffic Analysis Evaluation c. Description: Traffic Analysis evaluation of existing IHSDM Pike. d. Evaluation type: Traffic Analysis d. Click on Next
II. Set the Evaluation Attributes 1. Set traffic analysis attributes : a. Evaluation bounds: the defaults are the start and end stations of IHSDM Pike. Keep these default values. b. Configuration Name: Default c. Upstream Alignment: i. Increasing stations: Level Sharp Curves ii. Decreasing stations: Level Tangent d. Click Next 3
2. Set traffic flow, for both directions: a. Vehicle Flow Rate (v/h): 400 b. Percent Trucks (%): 7 c. Percent RVs (%): 0 d. Click on the Generate Platoons Percents button to auto calculate the Entering Platoons (%) in both directions. e. Click Next 4
3. Set desired speeds : Accept the default values for mean desired speeds and for standard deviations for both directions, and click Next. 5
To enter data for Reduced Speed Zones and Crawl Regions, click on the corresponding buttons 4. Set highway elements : a. Reduced Speed Zones: At this time, we do not have data to identify reduced speed zones, so no action is needed. b. Crawl Regions: At this time, we do not have data to identify crawl regions, so no action is needed. c. Under No Passing Zones, verify that the Minimum Sight Distance is 1050.00 ft, and the Passing Zone Minimum Length is 400 ft. Click on the Calculate button. d. The progress of the No Passing Zone calculation is shown on a pop-up progress bar. Once it is completed, the bar disappears. Then click on Next to proceed. 5. Set simulation settings : a. Click on the Generate Warm-up Period button to have the Warm-up Period auto calculated. b. Click on the Simulation Seeds button 6
On the Edit Simulation Controls pop-up window, click on the Generate New Seeds button to generate a set of random number seeds for the simulation. Then click OK to close this window. c. Under Report Options, the default Report Start and Report End stations are close to the evaluation bounds (16.404 ft or 5 m from each end of the highway). The default Report Interval is 300 ft. Click on the Generate Stations button to generate report stations according to these default values. d. Click on Edit Stations to view the newly generated report stations, then click on Cancel to close the pop-up window. Note: Generating the random number seeds is optional. 7
6. Click Next to proceed. 7. Set graph settings : Accept the default selections, and click Next. 8
8. IHSDM checked the highway data provided vs. the data that could be used for the traffic analysis evaluation. The Data issues screen lists data elements that may need further review. The Passing Lane, Climb Lane, Reduced Speed Zones, and Crawl Region elements should appear in the list. Since IHSDM Pike does not have Passing or Climbing Lanes, and we do not wish to enter Reduced Speed Zones or Crawl Regions, confirm that no changes are needed to the data at this time by selecting Next. TIP: To make changes to a data element listed in the table, click on the data element name to bring up a data editor for that element. 9. On the Evaluation settings summary screen, check the summary to ensure that the previous steps were completed properly. Make sure the box is checked for Show Report on Run Completion. Click Run to run the Evaluation. 9
III. Run TAM Evaluation 1. The status screen shows the progress of the evaluation. Once it is completed, the Show Report, Graph-Increasing (graphical results for travel in the direction of increasing stations), and Graph- Decreasing (graphical results for travel in the direction of decreasing stations) buttons become active. The Evaluation Report should open in an html browser automatically. Minimize the report for later access. IV. View/Interpret TAM Output 1. Generate TAM graphic output outside of the evaluation report: a. Click the Graph-Increasing button on the status screen to open a traffic analysis results graph in the Graph Editor. Click on the maximize icon in the upper right corner of the window for a better view. b. If a legend is not visible, select View then Toggle Legend from the pull-down menu. The legend should appear below the graphs. Make the graph full screen. 10
Q 6.1.1: At approximately what station is the mean speed for trucks the lowest? Station and value for the lowest mean speed for trucks a. Close the graph window by clicking on the X 2. View/Interpret TAM Evaluation Report: a. Click the Show Report button b. Scroll through the Evaluation Report (or click on the link in the Table of Contents) to find the Section Summary table Graphs are also available in the Evaluation Report, in default formats. Q 6.1.2: What is the Percent Time Spent Following (Combined)? Q 6.1.3: What is the Average Travel Speed (Combined)? Percent Time Spent Following (Combined) Average Travel Speed (Combined) c. Scroll down to the Station Summary (direction of increasing stations) table 11
Q 6.1.4: What is the Simulation Speed Characteristic Mean for Trucks, around station 5+416 for the Increasing stations direction? Q 6.1.5: What is the Platoon Size at the same report interval (around station 5+416) for the Increasing stations direction? Simulation Speed Characteristic Mean for Trucks, around station 5+416 for the Increasing stations direction (mph) Platoon Size at the same report interval (around station 5+416) for the Increasing stations direction d. Close the Evaluation Report. e. Close the Status screen by clicking the Close button. 12
Work Problem Answer Key Exercise 6.1 Q 6.1.1: At approximately what station is the mean speed for trucks the lowest? Station and value for the lowest mean speed for trucks Station 5+200, speed 35 mph Q 6.1.2: What is the Percent Time Spent Following (Combined)? Q 6.1.3: What is the Average Travel Speed (Combined)? To access a pre-produced copy of the Evaluation Report for Exercise 6.1: 1. Go to the Tutorial/Evaluation_ Reports folder under your IHSDM directory. 2. Choose Exercise_6.1_TAM_ Report.htm Percent Time Spent Following (Combined) Average Travel Speed (Combined) 52.2 % 50.6 mph Q 6.1.4: What is the Simulation Speed Characteristic Mean for Trucks, around station 5+416 for the Increasing stations direction? Q 6.1.5: What is the Platoon Size at the same report interval (around station 5+416) for the Increasing stations direction? Simulation Speed Characteristic Mean for Trucks, around station 5+416 for the Increasing stations direction (mph) Platoon Size at the same report interval (around station 5+416) for the Increasing stations direction 33 3.6 Go back to: Table of Contents Go to the next lesson 13