Detour. During the bridge replacement project, a temporary detour road and short single-lane bridge is proposed to be constructed 1,300 feet downstream from the existing bridge. The detour road will connect Mattole Road via Burrel Road and will also provide the main access to the bridge construction site. Detour road construction will consist of river run gravel fill over geotextile fabric, with an aggregate base topping. The temporary detour bridge will cross the main low-summer-flow channel of the Mattole River and will most likely consist of a portable Xxxxxx Bridge or other erectable bridge type. The temporary bridge will be used during the second construction season only and set at an elevation with sufficient height to clear summer river flow and meet Burrel Road grade. Staging Temporary staging areas will be available at three locations: (1) along Xxxxxx Ridge Road, just southeast of the intersection with Mattole Road; (2) all along the south bank gravel bar near and beneath the existing bridge and; (3) at the north Mattole Road Bridge approach. The Xxxxxx Ridge Road staging area is located along the east side of Xxxxxx Ridge Road, approximately 300 feet south of the intersection with Mattole Road. The south bank gravel bar temporary staging area (primary construction staging area) will be located between the detour road located 1,300 feet to the west and the private access road a few hundred feet upstream from the bridge. The north approach staging area will be located on Mattole Road, immediately north of the existing bridge north abutment.
Detour. For either the shorter plan or intermediate plan, restricted traffic use and closure of the viaduct would require the establishment of a traffic detour on First Avenue S. It is anticipated that this detour would be used for nearly the entire duration of the construction period. The use of a designated detour would help people traveling to and from downtown because it would be a predictable alternate route. This detour is adjacent to the sports stadiums and could exacerbate traffic congestion on days sports events are held. The proposed First Avenue S. Xxxxxx also travels through the heart of a mixed‐use low‐density neighborhood. The Pioneer Square neighborhood and specifically First Avenue S. have many residents, including low‐income and minority residents. This increased traffic and congestion on First Avenue S. would change the current neighborhood character of the Pioneer Square area, disrupt everyday activities in the neighborhood, and reduce access to social and community services. The detour route would be used 24 hours a day, which would increase nighttime noise, light, and glare experienced by adjacent residents living in upper floors of First Avenue S. buildings. Moreover, the First Avenue S. Detour would traverse the middle portion of the Pioneer Square neighborhood and effectively act as a barrier separating the three blocks between First Avenue S. and Alaskan Way surface street (i.e., the construction corridor) from the remainder of the neighborhood. The effects of the traffic detour could exacerbate adverse effects on the social resources located along this narrow corridor immediately adjacent to the construction corridor.
Detour. The use of a traffic detour on First Avenue S. would be required for the longer plan. The effects of this traffic detour are described above in Section 6.2.3.
Detour
