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j' <br /> Mr.Bruce Westby,PE <br /> March 21,2017 <br /> a <br /> Page 4 <br /> movement, where protected left turn phasing was run together for these movements <br /> with no conflicts between either direction's left turn movements. Left turn <br /> movements are offset far enough such that no conflicts in left turn paths are <br /> i <br /> occurring. <br /> 2. As mentioned,the westbound approach has two left turn lanes. For this approach, the <br /> MnDOT Manual suggests that protected operation be utilized during the higher <br /> volume periods of the day with Engineering judgment being used to determine if <br /> flashing yellow operation could be used for all other times of the day. <br /> 3. There are less than 3 opposing lanes of through traffic facing each intersection ' <br /> approach. <br /> 4. The intersection does not have a high crash rate and there is no significant history of <br /> right angle crashes involving left turning traffic. �. <br /> crash history for left turnip traffic and traffic volumes are <br /> In summary, as there is no significantry g <br /> likely lower for the entire intersection (outside of the peak traffic periods), the City should be <br /> able to consider using Flashing Yellow Arrow operations at this intersection throughout much of <br /> operation of the <br /> a typical weekday and throughout the weekend. In addition, any changes to the o p <br /> left turn signal phases are not anticipated to impact overall operations of the intersection in a <br /> y (andwa <br /> negative delays for left turning traffic will decrease with flashing yellow arrow <br /> g <br /> operations which will improve the overall operation of the intersection). For peak traffic periods <br /> though (and for when sun becomes an issue for eastbound and westbound traffic), protected left <br /> turn operation is strongly recommended to be implemented. <br /> So <br /> me modifications to the existing g y signal system installation will be required to revise the <br /> operation of this signal system and add flashing yellow arrows for each intersection approach. <br /> p g Both overhead end mounted and far left pole mounted left turn signals for each intersection <br /> approach will required having 3--section RLA-YLA-GLA signal heads replaced with 4-section <br /> RLA-YLA-FYLA-GLA pp <br /> signal heads. For the westbound approach (due to the dual left turn <br /> g <br /> lane), a 5--foot extension will be required to be added to the mast arm facing this approach so that f. <br /> two 4-section overhead signals can be installed and centered on each left turn lane (requirement <br /> that each approaching left turn lane have its own flashing yellow arrow signal centered on each <br /> left turn lane). No additional through signal heads will be required to be installed facing any of <br /> g g <br /> r, <br /> the four approaches, as there are already separate through (RYG) signal heads centered on each <br /> pp R <br /> through lane. Some additional cabling (6/c#14) will be required to be installed to operate new <br /> flashing y arrow yellow signal heads on all four intersection approaches based on a review of the <br /> g <br /> field wiring diagram. No new conduit will be required to be installed to accommodate <br /> installation of these new cables. <br /> With regards to left turn lane detection, the MnDOT Traffic Control Signal Design Manual <br /> recommends that either four loop detectors be installed for proper detection (at 5 , 20 3 5 and <br /> 50' from the stopbar or crosswalk or that two separately wired loop detectors be installed for <br /> ) p <br />