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Ms. Jane Rose October 12, 2015 Page 2 components to determine if additional electrical equipment would be required to be provided in order to allow for flashing yellow arrow operation to be used. As part of the signal system installation, each intersection approach was set up to operate with protected left turn phasing (3 -section RLA-YLA-GLA signals). The intersection has a newer TS2-Type 1 controller cabinet and an Econolite ASC -3 controller, both of which are compatible with upgraded left turn (i.e. flashing yellow arrow) operations. There are sufficient load switch bays open and available to add flashing yellow arrow operation without significant modifications to the existing controller cabinet. Finally, the conflict monitor (Reno MMU -1600) is an older model but is capable of operating flashing yellow arrows for all intersection approaches. Regarding the conflict monitor (and all other controller cabinet equipment), we contacted Traffic Control Corporation to confirm that these items are compatible for flashing yellow arrow operations. Traffic Control Corporation suggested that the County may want to consider upgrading the conflict monitor to a newer MMU- 1600GE model which has a display screen for more efficient diagnosis of any traffic signal related issues (the 1600 model does not have the display screen). Estimated cost to upgrade the conflict monitor is around $1,200. However, upgrading the conflict monitor is NOT required for flashing -yellow arrow operation. As part of our analysis, SEH utilized the Minnesota Department of Transportation's (MnDOT) flashing yellow arrow installation criteria from their "Traffic Signal Timing and Coordination Manual' to analyze extended usage of flashing yellow arrow operations for each intersection approach. A copy of this criteria is attached for your information. Based on comparison of available data with the MnDOT criteria, the following can be inferred: The design of this signal system likely included the initial recommendation of protected left turn phasing for each intersection approach due to the higher posted speed limits on each approach (as is typical Anoka County practice). As mentioned above, posted speed limits range from 45 mph on CSAH 14 to 50-55 mph on CSAH 54. With regards to utilizing Flashing Yellow Arrow operations for each left turn movement, the following should be noted: According to the current edition of the AASHTO Geometric Design of Highways and Streets manual, left -turning drivers "need sufficient sight distance to decide when it is safe to turn left across the lanes used by opposing traffic." This stopping sight distance along CSAH 14 for the design/posted speed of 45 mph is at least 360 feet of clear sight distance to the east and west. For northbound CSAH 54, the recommended stopping sight distance at 50 mph is as least 425 feet to the north. For southbound CSAH 54, the recommended stopping sight distance at 55 mph is least 495 feet to the south. Based on a field review of intersection geometries, each intersection approach is straight for several hundred feet in each direction with no impediments to the sight distance (other than possible sun issues for eastbound traffic in the AM peak hour and for westbound traffic in the PM peak hour during fall -winter months). Based on this information, available stopping sight distance meets this criteria for each intersection approach. • Based on the recent crash history at this intersection, only I crash was reported between 2012 and 2014. This crash was a property damage right angle crash between southbound 124