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o Mn/DOT Traffic Signal Timing and Coordination Manual Use of posted speed limit is recommended. Non -arterial approaches may have lower speeds than the posted speed limit because they are often in a stop condition upon the arrival of traffic. Grades affect the acceleration rate of the left turner and the stopping distance and speed of the opposing through traffic and are therefore considered in conjunction with speeds. ✓ Cross Product: The left turn volume multiplied by the opposing through volume. The cross product values used are taken from the Wisconsin Department of Transportation (WisDOT) Traffic Signal Design Manual discussion on left turn conflicts analysis, Chapter 2, Section 3, Subject 4. Cross product used represents a high frequency of conflicts for left turners looking for gaps In through traffic. FYA during Free Operation With the variable -phasing operation of the FYA head, free operation will no longer have an assigned fixed phasing operation. therefore, standard free operation will need to be set up In the signal controller so technicians can put signals quickly to FREE with a standard phasing operation desired at the specific time. Here is an example of the standard FREE operations that will need to be set up in the signal controller. 1. All left turns protected 2. All left turns protected/permissive 3. All left turns permissive 4. Mainline protected, cross street protected permissive S. Mainline protected, cross street permissive 6. Mainline protected/permissive, cross street protected 7. Mainline protected/permissive, cross street permissive 8. Mainline permissive, cross street protected 9. Mainline permissive, cross street protected/permissive Minimum Green Times Minimum Green Times Mn/DOT currently sets the minimum green time based on the type of phasing operation where protected lefts have a 7 second minimum green and protected/permissive lefts have a 5 second minimum green. Given the FYA head is a variable phasing operation head, a decision will need to be made as to if there should be more than one minimum green value that changes with the phasing operation, or if a universal minimum green should apply to all phasing operations. If one minimum green Is used, and if a left turn phase will ever run protected, the left turn minimum green should be set at 7 seconds. If a left turn will never run protected (i.e. only run protected/permissive or permissive), then the left turn minimum green should be set at 5 seconds. EVP Preemption Operation under FYA A. Protected -only Operation ✓ When the FYA is not allowed (protected only), the pre-emption will bring up the protected left turn and the adjacent through phase. The opposing FYA will not be allowed during preemption (refer to Exhibit 3-15). May 2011 Local Intersection Concepts Page 13-31 140