02-19-2008 Agenda - Laserfiche WebLink

by snow plow operators. A number of communities have reported that their drivers have not had significant difficulties cleaning snow from the modern roundabouts. Traffic Volumes and Turning Movernents: Current and projeeted traffic volumes and turning rnovements are below the eapacity of a single lane roundabout at this intersection. The roundabout traffic analysis eornpleted by SRF for the intersection is included and discusses this in more detail. Future Retrofit to accomrnodate future reconstruction of Sheyenne Street or 52'd A venue: If a single lane rnodern roundabout is constructed now, it rnay require replacernent to accommodate future reconstruction of Sheyenne Street and 52'd Avenue. Roundabouts can generally be widened frorn a single lane to a double lane. However it rnay be more difficult in this instance in that that centerline location of the roads could change in the future to accornrnodate a new/widened bridge on 52'd Avenue and widening of Sheyenne Street entirely to the west to move away frorn the River. Richard Lane and I can discuss this question further during the meeting. If a single lane roundabout was built now and it had to be reconstructed in 10 to 20 years, it would still likely prove to be a good investrnent. The cost now is estirnated at only $77,000 more than a conventional non-signalized intersection and is $107,000 less expensive than a conventional signalized intersection. Each ofthe conventional intersections may also require reconstruction to accornmodate a future urban section. Conclusions: I believe a rnodern single lane roundabout would be a good alternative at the 520d A venue intersection location for several reasons: It would be safer than a conventional signalized or un-signalized intersection It would be less expensive than a signalized intersection The rnaintenance would be less expensive than a signalized intersection It would rnove traffic with fewer delays than a conventional intersection That said there are several disadvantages to a modem roundabout at this location. The roads to the north and east will likely require reconstruction to 5 lane urban sections in the future and this rnay necessitate reconstruction of the roundabout at the intersection. The close proximity and narrow width of the 52nd A venue Bridge pose sorne challenges to the design of the roundabout. J:\Admin-EngICommisJion Corrsp\200S Commission Corrcspondence\MlIdern Roundabout Discussion 2.l2.200S.doc 2