8.5. SR 01-09-1995 - Laserfiche WebLink

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. M~ ~ l'fI\SI11'l\1; E\mm:KS 1326 Energy Pork Drive St. POlll, MN 55108 612.644-4389 1.800.888.2923 Fox: 612.644.9446 CIVil ENGINEERING: ENVIRONMENTAL MUNICIPAL e PLANNING SOLID WASTE STRUCTURAL SURVEYING TRAffiC TRANSPORTATION ELECTRICAL/MECHANICAL ENGINEERING HVAC PowER DISTRIBUTION SCADA SYSTEM CONTROLS OFFICES IN ~INNEAPOl1S PRIOR lAKE ST. PAUL WASECA January 3, 1995 File: 230~216-30 Mr. Pat Klaers City Administrator City of Elk River 13065 Orono Parkway P.O. Box 490 Elk River, MN 55330 RE: SCHOOL STREET SIGNALIZATION Dear Mr. Klaers: As you may be aware, there have been some initial start-up problems with the two signal systems on School Street located at Jackson Avenue and Freeport Avenue. We have investigated both signal systems and have determined the source of the problems. This correspondence is intended to bring you up to date on the status of those signals and the corrective actions that have been taken. The concern raised about the signal system at School Street and Jackson Avenue was the School Street leg turned from green to red too quickly to allow the flow of a reasonable number of school buses at the morning and afternoon school traffic flow. This signal system is set up to allow a maximum of a 90 second green time for the School Street flow. The loop detectors have been set with a 3.5 second delay in them. In other words, as long as they continue to detect vehicles within 3.5 seconds, the green light will stay on for a maximum period of 90 seconds before shifting to the green cycle for Jackson Avenue. Apparently with school buses backed up, their acceleration rate is slower than 3.5 seconds; therefore, the loop detectors have detennined that there is no vehicle approaching and have caused the green cycle for School Street to be cut short. This can be easily remedied by increasing this detection time. The concern is that we do not want to increase it so long that during off-peak times, the green cycle for School Street remains longer than necessary because periodic vehicles trip the loop detectors. We have explained this situation to Phil Hals and will work with him to experiment on the delay time for the loop detectors to get the appropriate setting for school bus flow. The signal system at Freeport Avenue and School Street has had a problem with a long green time being allowed for southbound Freeport even though no vehicles have been present there. A reanalysis of the loop detectors has determined that two of the detectors for southbound Freeport are bad and this has caused the problem. The bad loop detectors have been essentially telling the control panel that vehicles are present when, in fact, they