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; <br /> Mr.Bruce Westby,PE <br /> March 21,2017 <br /> Page 5 <br /> ' and 40' from the stop bar or crosswalk. Recent Count { <br /> existing signal system retrofits at 10 a p Y <br /> p <br /> p <br /> ractice has been to have the four separate loop detectors installed in each left turn lane in order c <br /> to be able to operate the left turn lanes on non-lock operation. For this signal system, left turn <br /> lane detection was installed at 10' and 40' from the stop bar for the northbound, southbound, and <br /> westbound approaches (each wired separately), <br /> y), while the eastbound approach has four loop <br /> detectors installed in the left turn lane. To meet current County practice, additional loop E <br /> detectors will be required to be furnished and installed 25 feet and 55 feet from the stop bar in <br /> the northbound and southbound left turn lanes as well as in both westbound left turn lanes (for a <br /> total of 8 new loop detectors). No additional 2/c#14 cables or controller cabinet loop detector i <br /> cards will be required to operate these new loop detectors since existing loop detectors are <br /> E. <br /> already wired separately in each left turn lane. <br /> To allow for flashing yellow arrow operation, we estimate that these modifications (completed <br /> b an electrical signal contractor) will cost approximately $40,000. A detailed preliminary <br /> Y g <br /> engineer's estimate of costs is attached to this letter for your information. <br /> Overall, we do not see any issues with installation and operation of flashing yellow arrows for <br /> each intersection approach. However, should the City and County implement flashing yellow <br /> arrow modifications to this signal system, we recommend that the signal system initially v <br /> 17 <br /> operate with protected left turns during both the AM peak period (6:00-9:00 am) and the <br /> PM peak period (3:00-7:00 pm) due to higher traffic volumes, higher posted speeds, and <br /> dual left turn lanes through this area. For all other hours of the da <br /> the presence of d g Y and for <br /> all weekend hours, the City and County should be able to consider using flashing yellow arrow <br /> operations. <br /> Note that any changes es in the operation of this signal system should be monitored by the City and <br /> County, including annual review of crash data to ensure that crash frequency does not increase <br /> due to modified left turn signal operations. f <br /> Please review our analysis and feel free to contact me at 651.4 0 9 .2073 with any questions or <br /> concerns that you may have related to our analysis. a! <br /> a. <br /> We hope that this information provides you with insight needed to help evaluate and implement <br /> r <br /> the appropriate left turn operations for this intersection. <br /> ° <br /> Sincerely, r <br /> 1 Ir <br /> SHORT ELLIOTT HENDRICKSON INC. <br /> E <br /> John M. Gray,PE <br /> Project Engineer <br /> is <br /> Enclosures <br /> c: Jane Rose,Anoka County Highway Department <br /> is <br />