Home > Basic Signals > Exploration > Case Study 2

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Case Study 6

### Two Phase Signalized Intersection with High Volumes

In this case, we will be using the given volumes to find the optimal cycle length. If you have trouble with this case, use Case Study 1 as an example.

 Movement NBLT NBTH NBRT SBLT SBTH SBRT Volume 186 1275 66 31 374 50
 Movement EBLT EBTH EBRT WBLT WBTH WBRT Volume 152 649 80 75 133 131
 Desired v/c Ratio ((v/c)c) 0.85 Headway (h) 2 sec Peak Hour Factor 0.90 Lost Time per phase (tl) 3 sec Pedestrian Volumes 200 per hour Heavy Vehicles 8%

# Worksheet:

For this case study, we have an Excel worksheet which you may use or print out.  If you decide to use Excel, be sure to right-click the link and "save target as" or "save link as."  If you are asked for a password, just press escape.

# Step 1: Phasing Plan

Check for protected left turn phasing .

# Step 2: Volume Adjustment

Conversion of all volumes to tcus. The equivalent factors may be found here.

# Step 3: Critical Volume

Check your Critical Volume

# Step 4: Cycle length

Check your Cycle Length

# Step 5: Green Split

Check your green split values for Phase A and Phase B.

# Step 6: Signal Timing Plan

Signal Timing Plan includes the phasing plan, cycle length, and green splits.

# Step 7: NEMA Phasing

In order to input the timing plan into the controller, you must assign NEMA phase numbers to the phases (convert Phase A to NEMA Phase #, and so on). The link above should help with this.

# Step 8: Controller Settings

Follow all of the instructions given, especially the CLEAR and RESTART to ensure that your settings are properly implemented. Use the default all-red and yellow values (2 and 3 respectively).

# Step 9: CID Configuration

Download (if you haven't already) and open Case Study 2.trf

The turn types for this case study should all be set to "Perm".

# Step 10: Traffic Simulation

Use TSIS to open "NIATT Signal Timing Project - Case Study 2 - Simulation.trf"

# Step 11: Execute Trafvu

This program allows you to view an animation of your signal. Do not start the animation until the simulation has reached equilibrium - usually about three minutes.

Continue on to Case Study 3.