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2017-05-10 CC Packet
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2017-05-10 CC Packet
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Ms. Jane Rose <br />October 12, 2015 <br />Page 2 <br />components to determine if additional electrical equipment would be required to be provided in order to <br />allow for flashing yellow arrow operation to be used. <br />As part of the signal system installation, each intersection approach was set up to operate with protected <br />left turn phasing (3 -section RLA-YLA-GLA signals). The intersection has a newer TS2-Type 1 <br />controller cabinet and an Econolite ASC -3 controller, both of which are compatible with upgraded left <br />turn (i.e. flashing yellow arrow) operations. There are sufficient load switch bays open and available to <br />add flashing yellow arrow operation without significant modifications to the existing controller cabinet. <br />Finally, the conflict monitor (Reno MMU -1600) is an older model but is capable of operating flashing <br />yellow arrows for all intersection approaches. <br />Regarding the conflict monitor (and all other controller cabinet equipment), we contacted Traffic Control <br />Corporation to confirm that these items are compatible for flashing yellow arrow operations. Traffic <br />Control Corporation suggested that the County may want to consider upgrading the conflict monitor to a <br />newer MMU- 1600GE model which has a display screen for more efficient diagnosis of any traffic signal <br />related issues (the 1600 model does not have the display screen). Estimated cost to upgrade the conflict <br />monitor is around $1,200. However, upgrading the conflict monitor is NOT required for flashing -yellow <br />arrow operation. <br />As part of our analysis, SEH utilized the Minnesota Department of Transportation's (MnDOT) flashing <br />yellow arrow installation criteria from their "Traffic Signal Timing and Coordination Manual' to analyze <br />extended usage of flashing yellow arrow operations for each intersection approach. A copy of this criteria <br />is attached for your information. Based on comparison of available data with the MnDOT criteria, the <br />following can be inferred: <br />The design of this signal system likely included the initial recommendation of protected left turn <br />phasing for each intersection approach due to the higher posted speed limits on each approach (as <br />is typical Anoka County practice). As mentioned above, posted speed limits range from 45 mph <br />on CSAH 14 to 50-55 mph on CSAH 54. <br />With regards to utilizing Flashing Yellow Arrow operations for each left turn movement, the <br />following should be noted: <br />According to the current edition of the AASHTO Geometric Design of Highways and <br />Streets manual, left -turning drivers "need sufficient sight distance to decide when it is <br />safe to turn left across the lanes used by opposing traffic." This stopping sight distance <br />along CSAH 14 for the design/posted speed of 45 mph is at least 360 feet of clear sight <br />distance to the east and west. For northbound CSAH 54, the recommended stopping <br />sight distance at 50 mph is as least 425 feet to the north. For southbound CSAH 54, the <br />recommended stopping sight distance at 55 mph is least 495 feet to the south. Based on a <br />field review of intersection geometries, each intersection approach is straight for several <br />hundred feet in each direction with no impediments to the sight distance (other than <br />possible sun issues for eastbound traffic in the AM peak hour and for westbound traffic in <br />the PM peak hour during fall -winter months). Based on this information, available <br />stopping sight distance meets this criteria for each intersection approach. <br />• Based on the recent crash history at this intersection, only I crash was reported between <br />2012 and 2014. This crash was a property damage right angle crash between southbound <br />124 <br />
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