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Home My WebLink About023 Appendix V - Road Design ReportEngineering Report Road Design Aaker Phase 1 Subdivision Preliminary Report for Preliminary Plat Review October 2022 Rev. March 2023 Submitted to: City of Bozeman Engineering Department 20 East Olive Bozeman, MT 59715 Prepared by: Stahly Engineering and Associates 851 Bridger Drive, Suite 1 Bozeman, MT 59715 (406) 522-8594 Road Design 1 3/28/2023 Engineering Report Table of Contents General Information Description of Travel Paths Traffic Generation Pavement Design Signage and Striping Lighting Figures and Tables Figure 1. Vicinity Map Attachments/References C4.0 Street Plan C4.1 Street Sections and Detail C4.2 Street Details C6.0 Signage and Striping Traffic Impact Study Geotechnical Report Road Design 2 3/28/2023 General Information The Aaker Property consists of approximately 95 acres of vacant land located west of South 19th Avenue, north of Stucky Road, and extending west and north to the MSU BART Farm. Concept master planning and initial REMU and B-2M zoning of the Aaker Property envision a mixed-use development with commercial uses along South 19th Avenue grading to predominantly residential uses toward the north and west. The Phase 1 Subdivision includes the extension of Kagy Boulevard and the land to the north, comprising 31.73 acres, with a 63.68-acre restricted future development lot south of Kagy Boulevard. Phase 1 will create 7 lots for development with REMU zoning. Planned land use includes moderate density residential with some commercial uses integrated into lots adjacent to Kagy Boulevard. Subdivision streets consist of extensions existing City streets and new City streets. Streets will be owned and maintained by the City of Bozeman. The developer’s contact information is: West University, LLC 113 East Oak, Suite 4A Bozeman, MT 59715 The street system owner’s contact information is: City of Bozeman Public Service Department PO Box 1230 Bozeman, MT 59771-1230 Figure 1 shows a vicinity map of the Aaker Property and Phase 1 subdivision. Figure 1. Vicinity Map, Bozeman, Montana Road Design 3 3/28/2023 Design Criteria Streets within Aaker Phase 1 Subdivision will be designed in accordance the City of Bozeman Design Standards and Specifications Policy. Construction specifications will be Montana Public Works Standards and Specifications (MPWSS), and the City of Bozeman Modifications to MPWSS. Development of the Aaker property will transform this part of town from a community edge with few services, to a vibrant node near the intersection of two heavily trafficked arterials (South 19th Avenue and Kagy Boulevard). The transportation pathways proposed are designed to be relevant throughout and after this transformation. Forward thinking vision of a busy community hub is a critical design criterion. Description of Travel Paths Summary Within the context of the project there is a hierarchy of travel paths. Kagy Boulevard, an arterial, crosses the central portion of the site from east to west. Local Streets will provide lot access and systemic circulation within the Phase 1 Subdivision, adjacent neighborhoods, and future developments. Bike lanes, shared use pathways, and sidewalks will provide multi-modal opportunities and allow pedestrian travel between existing and planned neighborhoods, parks, and commercial centers. Arterial Streets– Kagy Boulevard Kagy Boulevard is a principal arterial street planned to extend to the west in the future. As a principal arterial, a 120’ right-of-way is proposed, providing space for capacity expanding improvements when required. Kagy Boulevard from South 19th Avenue to Willson Avenue is planned to be improved by the City in the near future. The City project will help define the community’s goals for this arterial street. West of South 19th Avenue the south side of Kagy Boulevard is currently incomplete, with a northern “half street” terminating at the Aaker property. As currently proposed, Kagy Boulevard will be widened and extended to the west boundary of the Aaker property. The proposed street width is based on a 71’ wide 2- lane arterial with two travel lanes, median treatment and protected left turn lanes. This street section will provide sufficient capacity for the entire Aaker property and possibly into the long-term. The proposed street section aligns well with existing portions of Kagy Boulevard between the site and South 19th Avenue. The proposed design also allows for future lanes to be added by narrowing the center median, ultimately supporting two travel lanes in each direction with a protected center turn lane. 10’-wide shared use pathways are proposed along both sides of the new portions of Kagy Boulevard to accommodate bicycle and pedestrian traffic. Road Design 4 3/28/2023 Access standards are proposed to be modified for intersections and planned approaches on Kagy Boulevard. A coordinated and systematic design can support accesses that are nearer than standard spacing. In order to provide a system of local streets and blocks, South 23rd Avenue is positioned 435’ from South 22nd Avenue instead of the 660’ required by code. Additionally, the distance between South 23rd Avenue and South 25th Avenue is 580’ instead of the 660’ required by code. Right-in- right-out lot approaches are proposed to be located between South 23rd Avenue and South 25th Avenue midway along this block. Full access lot approaches are proposed west of South 25th Avenue, but since these are at the end of the road access conflicts do not occur. When Kagy is extended to the west these approaches could be restricted to right-in-right-out to resolve access conflicts. Systematically these intersections and approaches produce an access spacing roughly equivalent to 1-block intervals, which is a reasonable balance between access and uninterrupted traffic flow. The Traffic Impact Study analyzed each access and shows that proposed spacing does not interfere with capacity or level of service, turning movements or vehicle ques, and has sufficient site distance for safe access. The remainder of Kagy Boulevard will have a 1’ no access strip, restricting access to the approved locations. Local City Streets – South 23rd Avenue, South 25th Avenue, Remington Way Aaker Phase 1 Subdivision will dedicate three new City local streets, South 23rd Avenue, South 25th Avenue, and Remington Way. South 23rd Avenue and South 25th Avenue will extend north from Kagy Boulevard to the northern subdivision boundary and will likely be extended to Lincoln Street in the future. Remington Way will be extended from eastern edge of the subdivision to South 25th Avenue. This is proposed to minimize fragmentation of the park and to avoid additional wetland impacts. The presence of this significant water course in relation to the planned location of future collectors (South 27th Avenue and Lincoln Street) make this street unnecessary. However, a street and utility easement is proposed through the park, in case this street extension is deemed necessary in the future. The proposed local street width is 35’ (measured from back of curb to back of curb) with 5’ sidewalks on each side, in 60’ rights-of-way. City utilities: water, sewer, and storm drainage, will be located within the proposed street rights-way. Private franchise utilities will be in 10’ easements running along the street rights-of-way, with utility sleeves installed for crossings. The 5’ sidewalk on the west side of South 25th Avenue is replaced with a 10’ pathway integrated into the park design. Lot Approaches Individual lots will be accessed by approaches from the streets constructed with subdivision improvements. Proposed approaches are based on the conceptual development plans to coordinate locations, allow sharing where possible, and maximize Road Design 5 3/28/2023 on-street parking. Approaches on local streets will be constructed in accordance with City of Bozeman Specifications. Sidewalks and Pathways All proposed streets will have sidewalks on both sides. Wider sidewalks are proposed to encourage non-vehicular travel. 10’-wide shared use pathways are proposed along both sides of the new portions of Kagy Boulevard to accommodate bicycle and pedestrian traffic. A 10’-wide shared use pathway is also proposed between the park and South 25th Avenue. When envisioned with future development in the area, these pathways will be important pedestrian and bike routes between existing and planned neighborhoods, parks, and commercial centers. Traffic Generation A Traffic Impact Study (TIS) has been conducted by Sanderson Stewart and is provided separately with the subdivision submittal. The TIS shows that all on-site and nearby intersections and accesses function at a Level of Service C or better with the planned improvements, with the exception of Kagy Boulevard, which is scheduled to be improved as a City of Bozeman Capital Improvement project. Additional turn lanes or restricted turning movements are not required to accommodate the subdivision traffic. Pavement Design The Geotechnical Report (provided separately) provides pavement design for the project streets in accordance with City of Bozeman Standards. This analysis is conducted in accordance with AASHTO Flexible Pavement Design Standards. The preliminary analysis is based on a soil California Bearing Ratio (CBR) of 2.5. Kagy Boulevard Kagy Boulevard, an arterial street, is designed for 20-year equivalent single axle loadings (ESAL) of 1,314,000. This analysis results in a total pavement section of 32” over a geotextile reinforcing fabric. The required pavement section consists of 21” of sub-base gravel, 6” of crushed road base gravel, and 5” of asphalt. Local Streets Local Streets are designed for 20-year equivalent single axle loadings (ESAL) of 292,000. This analysis results in a total pavement section of 30” over a geotextile reinforcing fabric. The required pavement section consists of 21” of sub-base gravel, 6” of crushed road base gravel, and 3” of asphalt. Road Design 6 3/28/2023 Alternate Sections Alternate Sections are included for each standard section in the construction drawings. These alternate sections are generally based on the exclusion of geotextile fabric in areas with a native sandy gravel subgrade or; the inclusion of a stronger geotextile reinforcing fabric in areas with a native silt or clay subgrade. All of the included alternate sections include the same subbase, base, and asphalt thicknesses as the standard sections. Traffic-rated, reinforced concrete will have a similar section as the streets, but with upper 9” comprised replaced with of 6” of reinforced concrete over 3” of crushed road base gravel. Signage and Striping Proposed street signage will be in accordance with the Manual of Uniform Traffic Control Devices (MUTCD). Proposed street signage is shown on the preliminary Civil Plan, C6.0 – Phase 1 Signage and Striping Plan, provided with the subdivision submittal. Proposed signage consists of stop signs at intersections, street name signs, pedestrian crossing warning signs at the park crosswalk, and no parking signs for intersections and crosswalks. Proposed striping consists of lane lines on Kagy Boulevard, bike lane symbols, crosswalks, stop bars and yield triangles. Type B panel type crosswalks with yield triangles and appropriate warning signs are proposed for the crosswalks crossing South 25th Avenue at Remington Way, leading to the park. Lighting Street lighting is proposed for all streets conforming to City of Bozeman Standards. A Special Improvement Lighting District (SILD) will be formed to pay for operation and maintenance of the street lighting. Lighting will be designed with street infrastructure, after Preliminary Plat. As preliminarily planned, Kagy Boulevard will have continuous, staggered street lighting. Local streets are not required to have continuous lighting but will have lighting at intersections and one-block intervals. 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