Agenda - Council - 08/08/2016 - Laserfiche WebLink

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43 LOCAL STATE-AID ROUTE STANDARDS,FINANCING 8820.9981 8820.9981 MINIMUM DESIGN STANDARDS: NATURAL PRESERVATION ROUTES,DESIGNATED NATIONAL FOREST HIGHWAYS WITHIN NATIONAL FORESTS,AND STATE PARK ACCESS ROADS WITHIN STATE PARKS;NEW OR RECONSTRUCTION PROJECTS. Subpart 1. Type I route. New or reconstruction projects for type I natural preservation routes, designated national forest highways within national forests, and state park access roads within state parks must meet or exceed the minimum dimensions indicated in the following design chart. Surface Design Lane Shoulder Inslope Clear Zone Design Bridge to Type Speed Width Width Strength Remain (mph) (feet) (feet) (rise: (feet) (tons) (feet) run) (a) (b) (c) (d) Aggregate 30 11 1 1:3 3 22 Paved 30 11 2 1:3 9 9 22 (a)If the route has scenic vistas that will require parking vehicles along the shoulder, widening the shoulder at these locations is acceptable. The designer will provide a four-foot paved shoulder if the route is a popular bicycle route. (b)Applies to slope within the clear zone only. Other design features,such as guardrails or retaining walls,should be considered in particularly sensitive areas in lieu of reconstruct- ing the inslope in accordance with part 8820.4060. (c) Guardrail is required to be installed at all bridges where the design speed exceeds 40 mph, and either the existing ADT exceeds 400 or the bridge width is less than the sum of the lane and shoulder widths. Mailbox supports must be in accordance with chapter 8818. (d) Inventory rating of HS 15 is required. A bridge narrower than these widths may remain in place if the bridge is not deficient structurally or hydraulically. HS 20 loading with AASHTO Standard Specifications or HL-93 loading with load and resistance factor design (LRFD) is required for new bridges. HS 18 loading is required for all rehabilitated bridges. The curb-to-curb minimum width for new or reconstructed bridges is the sum of the lane and shoulder widths plus four feet. Ditch depths and widths must be kept to the minimum required to function hydrauli- cally and to provide for adequate snow storage when a standard ditch would negatively impact the surroundings. The designer shall specify in the plan and special provisions that the clearing width is to be kept to the absolute minimum. In sensitive areas,the normal clearance allowed to a contractor for working room is zero unless otherwise required for special conditions. Curb and gutter may be used in lieu of a ditch section under the paved option. The lane width, shoulder width, and clear zone must be maintained. For designated national forest highways within national forests, and state park access roads within state parks,this subpart applies only where the projected ADT is less than 100, unless the route has been designated as a natural preservation route. For roundabout design,the design criteria of the current edition of the Minnesota State Aid Roundabout Guide are recommended.