6.9. SR 06-18-2007 - Laserfiche WebLink

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HIGHWAY 169 PRELIMINARY DESIGN AND ENVIRONMENTAL DOCUMENTATION- ELK RIVER AREA SUMMARY OF PRELIMINARY EVALUATION June 4, 2007 For the purposes of developing access alternatives and performing a preliminary evaluation of impacts, the design team divided the Elk River area into two sub-areas: North of County Highway 33 sub-area and the South of County Highway 33 sub-area. Improvements grouped into the sub-areas, build alternatives considered, and results from the preliminary evaluation are discussed below. NORTH OF COUNTY HIGHWAY 33 SUB-AREA A. Improvements Grouped into Sub-Area . Frontage Road System from County Highway 25/19 to County Highway 33 237th Avenue (County Road 74) / 239th Avenue Overpass 221 st Avenue / Realigned County Road 121 Interchange . . B. Build Alternatives Considered Frontage Road System The design team developed alignments for the frontage and backage road system that were the same in most areas except where they tied into the specific interchange concept. The proposed alignments replaced all at- grade access to Highway 169. A continuous frontage road system is proposed on the east side of Highway 169 from County Highway 25/19 to County Highway 33. On the west side of Highway 169, the frontage road system will not cross the existing and planned land fill areas south of 237th Avenue and north of221st Avenue. The alignments of the frontage roads are approximate only - details will be developed as development occurs in the area. 239th Avenue (County Road 74) / 237th Avenue Overpass The design team considered two possible alignments for the 239th and 237th overpass. The northerly alignment would provide an overpass at 239th Avenue and connect to the proposed frontage road on the east side of Highway 169. The southerly alignment would provide an overpass at 237th A venue. Both alternatives remove existing intersections on Highway 169, provide continuous roadway connections between 239th and 237th Avenues, and connect to the frontage road system - providing access to Highway 169 at the 221st interchange to the south and/or the County Highway 25 / ] 9 interchange to the north. The northerly overpass alignment at 239th Avenue (Alternative F) was determined to have the least overall impacts of the two alternatives, and was therefore selected by the design team and the Local Advisory Committee as the Preferred Alternative. 221st Avenue / Realigned County Road 121 Interchange The proposed 22] st Avenue / Realigned County Road] 21 interchange provides a bridge under Highway 169 as well as full access to/from Highway 169. The original diamond interchange alignment provided an interchange at the same location of the existing 221 st Avenue intersection with Highway 169. The design team realigned 221 st A venue to the south in order to avoid impacts to the landfill and wetlands located in the northeast and northwest quadrants of the proposed interchange, respectively. This new alignment (Alternative E) extends 221st Avenue to the east to connect with County Road 121, and includes connections to frontage roads east and west of Highway 169. Based on the preliminary analysis, each alternative may require the relocation ofhome(s) in either the northeast or southeast quadrant of the interchange. However, Alternative E provides the best frontage road connectivity, avoids impacts to the existing wetlands, and avoids the possibility of impacts to the landfill. For these reasons, the design tearn and the Local Advisory Committee recommends Alternative E as the Preferred Alternative.