(A) Design.
(1) The arrangement, type, extent, width, grade and location of all streets must be considered in their relation to existing and planned streets, topographical conditions, public convenience and safety, and the proposed uses of the land to be served by them.
(2) Roads must meet the design specifications in Table 1.
(3) Where streets terminate, either a cul-de-sac or “T” turnaround must be provided at the terminus. Cul-de-sacs and “T” turnarounds must conform to the design specifications in Table 1.
(4) All streets must either be dedicated to the public or be private streets to be owned and maintained by an approved property owners’ association.
(5) Residential driveways must not have direct access to primary highways. Any vehicular access onto a state highway must be approved by the Montana Department of Transportation.
(6) Local streets must be designed to encourage through traffic. Dead end streets are discouraged and must provide a turn-around for emergency vehicles.
(7) Whenever a subdivision abuts or contains an existing or proposed arterial highway or major thoroughfare, the governing body may require frontage roads or other treatment as may be necessary to adequately protect residential properties and to separate arterial and local traffic.
(8) Half streets are prohibited except when they are essential to the development of the subdivision and when the governing body is satisfied the other half of the street will be dedicated to the public when the adjoining property is subdivided. When an existing half street is adjacent to a tract to be subdivided, the other half of the street must be platted within the new subdivision.
(9) The alignment of all streets and roads must provide adequate sight distances.
(10) Intersections. The following requirements apply to intersections:
(a) Streets must intersect at 90 degree angles except when topography prohibits this alignment. In no case may the angle of an intersection be less than 60 degrees to the centerline of the roadway being intersected.
(b) Two streets meeting a third street from opposite sides must be offset at least 125 feet for local roads and 300 feet for arterials or collectors.
(c) No more than two streets may intersect at one point.
(d) Intersections of local streets with major arterials or highways must be minimized where possible although the City’s emphasis is on maintaining the existing street grid.
(e) Intersections must be designed to provide adequate visibility for traffic safety based on the designed operating speeds of the intersecting roadways.
(f) Hilltop intersections are prohibited, unless no alternatives exist. Intersections on local roads within 100 feet of a hilltop are prohibited. Intersections on arterial and collector roads within 200 feet of a hilltop are prohibited. If no alternative to a hilltop intersection exists, additional traffic-control devices will be required.
(g) The grade of approaches to major highways may not exceed 5%.
(11) Names of new streets or roads aligned with existing streets must be the same as those of the existing streets. Proposed street names may not duplicate or cause confusion with existing street names.
(12) Proposed road plans and profiles as required by § 9.6.25 are subject to approval by the City Engineer or Public Works Department.
(B) Improvements.
(1) All roadway improvements including pavement, curbs, gutters, sidewalks and drainage must be constructed in accordance with the specifications and standards prescribed in these regulations using materials approved by the governing body.
(2) Roadway subgrades must be free of topsoil, sod, vegetation or organic matter, soft clay, and other substandard materials. Subgrades must be properly rolled, shaped, and compacted, and must be approved by the governing body.
(3) Streets and roads must be designed to ensure proper drainage. This may require surface crowning, culverts, curbs and gutters, drainage swales and storm drains.
(4) (a) Where access from a public road to the subdivision will cross properties not owned by the subdivider, the subdivider must obtain proper easements of sufficient width to satisfy the requirements of Table 1. Easements must be granted by each property owner in a signed and notarized document.
(b) The location of any road easement must be shown on the plat or on a supplemental map. The existence of easements must be noted on the face of the final plat and on any deeds or other instruments conveying lots within the subdivision.
(5) Existing trees and other vegetation must be preserved whenever appropriate. Plantings may be required for buffering, screening or prevention of soil erosion and are subject to approval by the City Council.
(6) Street lights will be required in subdivisions proposed within or adjacent to areas with existing street lighting. Street lighting may be required in other areas when necessary to protect public safety. Street lighting will be consistent and compatible with the existing street lighting in the City.
(7) Street or road signs and traffic-control devices of the size, shape and height approved by the governing body must be placed at all intersections. Traffic-control devices must conform to the standards contained in the Manual on Uniform Traffic Control Devices available from the Montana Department of Transportation.
(8) When required by the United States Postal Service, the developer must provide an off-street area for mail delivery.
Table 1: Road Standards for Subdivisions | |||
Minimum Design Standards | Collector | Local Road | |
Table 1: Road Standards for Subdivisions | |||
Minimum Design Standards | Collector | Local Road | |
1. Minimum Right-of-Way Width | |||
a. Level terrain | 60 ft. | 60 ft. | |
b. Hilly terrain | 60 ft. | 60 ft. | |
2. Minimum Roadway Width | 26 ft. | 24 ft. | |
3. Minimum Curb Radius or Edge Pavement at Intersections | 25 ft. | 15 ft. | |
4. Maximum Grades | 8% | 10% | |
5. Approaches Onto Public Roads | |||
a. Minimum Sight Distance | 200 ft. | 150 ft. | |
b. Maximum Grade for 20 ft. | 5% | 5% | |
6. Curvature | |||
a. Design Speed | 30 mph | 20 mph | |
b. Minimum Radius | 250 ft. | 150 ft. | |
7. Turn Arounds | |||
a. Maximum Dead End Road Length | 1,000 ft. | ||
b. Cul-De-Sac Outside ROW Radius | 40 ft. | ||
c. Cul-De-Sac Roadway ROW Radius | 35 ft. | ||
d. “T” Turn Arounds Leg Length | 30 ft. | ||
8. Bridges | |||
a. Roadway Width | 26 ft. | 24 ft. | |
b. Design Capacity | 20 tons | 20 tons | |
c. Vertical Clearance | 14.5 ft. | 14.5 ft. | |
(Res. 607, passed 7-1-2019)