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HomeMy WebLinkAbout007 Oxbow PH2 Traffic Analysis October 15, 2024 Mr. Adam Schlegel Cushing Terrel 411 E Main St #101 Bozeman, MT 59715 Reference: Traffic Analysis – Cottonwood Subdivision, Phase 2 Project No. 24481 Dear Adam: The purpose of this letter is to provide a response to comments received from the City of Bozeman regarding Phase 2 of Cottonwood Subdivision located in Bozeman, Montana. Traffic impacts for this development were previously evaluated in the Cottonwood Subdivision TIS (February 2018) and the Cottonwood Subdivision TIS Update (January 2021), completed by Marvin & Associates. Future Traffic Projections Comparison It was requested that future traffic projections in the original report be compared to updated current volume data from MDT’s count station on Cottonwood Road, located south of Alpha Drive. In the original TIS from 2018, Cottonwood Road was reported to have an average weekday traffic volume of 4,950 vehicles south of Huffine Lane. With these volumes, the study area intersections operated at LOS C or better, with minimal queueing. In the 2018 TIS, it was assumed that 155 apartment units and 42 townhouses would be built in Phase 1 of Cottonwood Subdivision, and 184 apartments and 146 townhouses would be built in a future phase. Multifamily Housing (Low-Rise) – Land Use 220 and Multifamily Housing (Mid-Rise) – Land Use 221 were used to calculate trip projections for apartment units and townhouses, respectively. After pedestrian and bicycle trip reductions were calculated, the trip generation analysis resulted in a projected average weekday traffic of 3,394 vehicle trips generated from the development. An average annual growth rate of three percent was calculated in the 2018 study, which was based on traffic projections from ten potential developments within the study area that were considered based on discussions with City of Bozeman staff. Existing traffic volumes from 2018 were combined with background growth and weekday traffic generated from Cottonwood Subdivision, resulting in a 2033 weekday traffic projection of 10,500 vehicles on Cottonwood Road south of Huffine Lane. The Mr. Adam Schlegel October 15, 2024 Page 2 northbound and southbound approaches at the Huffine Lane/Cottonwood Road intersection were projected to operate at LOS D during the PM peak period in the Future scenario (year 2033). All remaining intersections were projected to operate at LOS C or better during both peak periods in the Future scenario (year 2033). The Cottonwood Subdivision TIS update from 2021 assumed construction of 104 apartment units, a fitness center, a clubhouse, and a coffee shop in Phase 1, and 188 apartment units in a future phase (now Phase 2). Multifamily Housing (Low-Rise) – Land Use 220, Health/Fitness Club – Land Use 492, Recreational Community Center – Land Use 495, and Coffee/Donut Shop without Drive-Through – Land Use 936 were used to calculate trip projections for the apartment units, fitness center, clubhouse, and coffee shop, respectively. After pedestrian and bicycle trip reductions were calculated, the trip generation analysis projected a total external trip generation of 2,591 average weekday vehicle trips for Phase 1 and Phase 2 combined. Phase 1 of the development has been built, and the number of apartment units planned for Phase 2 has decreased from 188 to 164 units. This 12.7 percent reduction in apartment units will result in a lesser impact on traffic operations within the study area. Phase 2 is now projected to generate 1,199 average weekday trips. Some reductions due to internal capture and alternate modes of transportation may be present, although they have not been accounted for in this analysis. An analysis of historical MDT traffic data from MDT’s count station on Cottonwood Road south of Huffine Lane (16-3A-019) showed a current AADT of 5,521 vehicles and an average annual growth rate of 3.3 percent over the last five years. This growth rate was applied to current traffic data and combined with the projected average weekday traffic generated from the 164 units in Phase 2 of Cottonwood Subdivision to calculate 2033 traffic volumes on Cottonwood Road. This calculation resulted in a projected weekday traffic volume of 10,200 vehicles on Cottonwood Road south of Huffine Lane. This updated 2033 traffic volume projection assumes that all of Phase 1 was constructed at the time of the most recent MDT traffic data on Cottonwood Road. The value of 10,200 vehicles is less than the 2033 traffic volume on Cottonwood Road projected in the original TIS of 10,500 vehicles. Therefore, study area intersections are unlikely to operate at worse conditions than initially projected. Mr. Adam Schlegel October 15, 2024 Page 3 Pedestrian Access Comments received from the City of Bozeman also requested an evaluation of pedestrian crossings along Cottonwood Road at Alpha Drive, Garfield Street, and Loyal Drive for potential safety enhancements. The MDT pedestrian crossing treatment selection matrix and MUTCD pedestrian hybrid beacon (PHB), also commonly known as a High intensity Activated crossWalK (HAWK), guidelines were therefore evaluated. Marked crosswalks with refuge islands and advanced yield markings are currently present at the Alpha Drive and Garfield Street intersections. There is no crosswalk at the Loyal Drive intersection and the nearest crosswalk is located approximately 600- feet north, at the Garfield Street intersection; therefore, a crosswalk should be considered at Loyal Drive if a refuge island could be implemented to reduce the crosswalk length and conflicting vehicular volume. However, the existing auxiliary left-turn lanes make a refuge island unviable at the Loyal Drive intersection in its current configuration. If a crosswalk were installed at this location, one of the left- turn lanes should be removed and replaced with a refuge island. For a crosswalk across a five-lane facility with a raised median, a speed limit of 45- mph, and AADT between 8,000 and 11,000 vehicles, the MDT matrix recommends consideration of an E-level treatment, which could include marked crosswalks with enhancements such as traffic calming, refuge islands, advanced yield markings, flashing beacons, or other high visibility treatments. The matrix also suggests the consideration of curb extensions and raised crosswalks. However, curb extensions and raised crosswalks are not recommended at this location due to the current speed limit along the corridor. As the existing crossings at Garfield Street and Alphas Drive currently provide a median refuge island, further treatments may not be necessary, but installation of additional markings or a flashing beacon may further improve safety. If daily traffic volumes on Cottonwood Road within the study area exceed 11,000 vehicles, which is likely to happen as traffic continues to increase on Cottonwood Road, the MDT matrix recommends consideration of an A-level treatment, which could include pedestrian-actuated beacons or a pedestrian signal. Both rectangular rapid flashing beacons (RRFBs) and HAWKs are considered pedestrian-actuated beacons. An A-level treatment is warranted for traffic levels above 11,000 vehicles regardless of the presence of a median refuge island. The MDT matrix is intended to be applied after following a flow-chart which includes a provision that a treatment should be selected if pedestrian volumes meet a minimum of 14 pedestrians per hour for speed limits at 45-mph. However, it is also noted that consideration may be given for latent demand, where crossings would occur if an appropriate crossing were present, and that the limits may be reduced Mr. Adam Schlegel October 15, 2024 Page 4 based on engineering judgment. For mid-block crossings, the flow-chart recommends 300-foot spacing from the nearest marked or controlled crossing but notes that this distance is approximate and may be reduced based on engineering judgment or where the crossing is on the path of a larger activity generator. Current pedestrian volumes were not collected for this analysis, but it is likely that some pedestrian demand will be present due to the volume of development ongoing on either side of Cottonwood Road. MUTCD HAWK guidelines show that a HAWK signal is not projected to be warranted at the Alpha Drive and Garfield Street intersections in 2033 due to the existing refuge island, which reduces the crosswalk length. At least 20 pedestrians crossing the major street per hour would be required to warrant a HAWK at the Loyal Drive intersection with existing geometry (no refuge island) and 2033 projected volumes. A HAWK would not be warranted if a median refuge were to be installed at the Loyal Drive intersection, thereby reducing the crosswalk length and the major street conflicting vehicle volume. MUTCD standards for the installation of RRFBs have yet to be developed, but the City of Boulder, CO Pedestrian Crossing Treatment Guidelines document, published in November 2011, provides a minimum pedestrian crossing value of 20 pedestrians per hour as guidance for RRFB installation. Although pedestrian activity was not recorded at the study intersections, pedestrian and bike mode trips were projected to be generated by the site. The updated TIS from 2021 projected a high of 16 pedestrian and bike trips to occur in the AM peak period. The majority of the pedestrian trips are projected to be generated from Phase 1 of the development, which includes a fitness center, a clubhouse, and a coffee shop. The analysis shows that Phase 2 of Cottonwood Subdivision is now projected to generate less vehicle trips than what was projected in previous reports. Therefore, this change should not present a negative impact on the transportation system within the study area. In combination with evaluation of pedestrian crosswalk volumes, consideration should be given to lowering the speed limit on Cottonwood Road within the study area and/or installing RRFBs at the intersections with marked crosswalks if daily volumes exceed the 11,000-vehicle threshold that dictates different treatment recommendations from the MDT matrix. If a crosswalk is desired at the Loyal Drive intersection, a pedestrian refuge island should be provided. Mr. Adam Schlegel October 15, 2024 Page 5 If you have any questions or concerns, please feel free to contact me at 406-922-4326 or astoltzfus@sabell.com. Sincerely, Audrey Stoltzfus, PE, RSP1 Project Engineer ROFT/ars P:\24481_Cottonwood_Sub_Ph_2_10.15.2024