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Ourston Roundabout Engineering TECHNICAL MEMORANDUM PREPARED FOR: PREPARED BY: Q/C and Q/A PROJECT NUMBER DATE: SUBJECT: PURPOSE Robert Schunicht — Landform Jedidiah Munroe, Ourston Roundabout Engineering, Inc. Mark Lenters, Ourston Roundabout Engineering, Inc. ORE 11-958 December 1, 2011 Operational Analysis Ramsey Parkway & Sunwood Drive Ramsey, Minnesota An operational analysis was completed for the proposed roundabout at Ramsey Parkway and Sunwood Drive located in the COR development project in Ramsey, Minnesota. The analysis also assessed possible queue spillbacks from the proposed roundabout to the signal at Armstrong Boulevard and Sunwood Drive. There is approximately 440 feet of queue storage between the signalized intersection and the proposed roundabout intersection. We understand that the queue space associated with the signal operations has been analyzed and the space requirements associated with the traffic signal control have been fulfilled by others to a satisfactory conclusion. We have also designed and analyzed an initial and potential ultimate roundabout lane configuration for the City's consideration. OPERATIONAL ANALYSIS METHODOLOGY Based on the AM and PM peak hourly traffic forecasts, the capacity of the roundabout intersection was analyzed using ARCADY roundabout design and capacity analysis software. ARCADY (Assessment of Roundabout Capacity and Delay) is a program based on U.K. empirical research into geometry -capacity relationships. Two features that ARCADY provides is its ability take into account horizontal geometric design sensitivity and its ability to be calibrated to the recent NCHRP Report 572 (Roundabouts in the United States, 2007) roundabout capacity model. The ARCADY analysis was calibrated to the NCHRP Report 572 empirical results, which indicate a reasonable 10% capacity reduction. The findings on capacity performance for U.S. roundabouts to date suggest that a reduction in the capacity modeling is appropriate pending the availability of more at -capacity data to improve the confidence of modeling roundabouts. Some single lane roundabouts are performing better than expected, but this may not be the case everywhere in the U.S., especially in areas where few roundabouts exist. The results represent the most probable capacity of the roundabout and employ capacity measures of level of service, delay and queuing, consistent with typical unsignalized capacity analysis methodologies (Highway Capacity Manual, 2010). The combination of using ARCADY with calibration allows for consideration of the U.S. data obtained by NCHRP. e Ourston Roundabout Engineering Operational Analysis Ramsey Parkway & Sunwood Drive Ramsey, Minnesota Page 1