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HomeMy WebLinkAbout006 Traffic StudyBoulder Creek Apartments Traffic Impact Study Bozeman, Montana Abelin Traffic Services 1 December, 2019 Boulder Creek Apartments Traffic Impact Study Bozeman, Montana A. EXECUTIVE SUMMARY The Boulder Creek Apartments is a six-acre residential development located south of Oak Street and west of Rosa Way in Bozeman, Montana. The project includes 112 new residential apartment units and would produce 609 new daily trips in the area at full build-out. As proposed, the Boulder Creek Apartments will not create any roadway capacity problems along Durston Road or Oak Street. The current roadway construction projects along Oak Street and Cottonwood Road will significantly alter traffic patterns in this area and will increase the overall roadway network capacity. All nearby intersections will continue to function at acceptable levels of service with the Boulder Creek Apartments and the additional anticipated developments in this area, including the new Bozeman High School. Long-range traffic volume growth in this area suggests the need for widening Cottonwood Road to a five-lane facility. This need was identified in the 2017 Bozeman Transportation Master Plan and implementation of roadway widening is currently being planned by the City of Bozeman. B. PROJECT DESCRIPTION This document provides an update of the possible effects on the surrounding road system from the Boulder Creek Apartments residential development located south of Oak Street and west of Rosa Way in Bozeman, Montana. The document also identifies any new traffic mitigation efforts that the development may require based on changes in the surrounding land uses and the current roadway network. The site is located south of Oak Street ¼ mile west of Cottonwood Road. The property would be developed to include up to 112 new residential apartment units. Based on the City of Bozeman Subdivision Regulations, the developers must study all affected intersections within ½ mile of the proposed development which includes the intersections of Durston Road with Laurel Parkway, Rosa Way, and Cottonwood Road. The intersection of Oak Street and Cottonwood Road is also within the project study area. Oak Street has recently been constructed to the west past Laurel Parkway and the intersection with Cottonwood Road is currently under construction as a multi-lane roundabout. There is limited available traffic data for this section of Oak Street, which will experience major traffic volume changes once all of the road segments currently under construction in this area are opened in 2020. For this reason, the intersection of Oak Street and Cottonwood Road has been analyzed only in general terms for this report. Boulder Creek Apartments Traffic Impact Study Bozeman, Montana Abelin Traffic Services 2 December, 2019 C. EXISTING CONDITIONS The proposed development property currently consists of a six-acre parcel of undeveloped land located south of Oak Street and west of Rosa Way. The topography in this area is flat. The site is located east of the Westbrook Phase 1 development, north of the Rosa Apartments, and west of the Traditions Subdivision. See Figure 1 for a location map of the proposed development. Figure 1- Proposed Development Site Adjacent Roadways Durston Road is a two-way east/west minor arterial route that provides access to the residential areas to the west of Bozeman. In recent years much of the road has been reconstructed to accommodate development in this area. Currently, the road has a three-lane cross-section with a paved width of 46-feet east of Laurel Parkway and has designated bike lanes. All cross-streets between Laurel Parkway and Cottonwood Road are controlled by STOP signs, except the intersection with Cottonwood Road which is currently signalized. The Laurel Parkway intersection is currently controlled by a four-way STOP. The roadway has a posted speed limit of 35 MPH and carried 9,100 Vehicles Per Day (VPD) in 2018. Boulder Creek Apartments New Road Segments Road Segments Currently Closed Boulder Creek Apartments Traffic Impact Study Bozeman, Montana Abelin Traffic Services 3 December, 2019 Cottonwood Road is a principal arterial north/south route that provides access to the residential developments to the north of Huffine Lane. The road currently has a three-lane cross-section north of Durston Road and a posted speed limit of 25 MPH. The roadway is currently under construction south of Durston Road and will include a new five-lane cross-section when completed in 2020. Rosa Way is a north/south local road that extends north from Durston Road. The road has a paved width of 32 feet with two lanes. The road has a posted speed limit of 25 MPH and is STOP controlled on all cross streets. Traffic Counts Large portions of Cottonwood Road and Oak Street are presently under construction with several major segments of Cottonwood Road closed both north and south of Durston Road. These road closures will persist into 2020. With the number of road closures in this area, it is not currently possible to get reliable traffic data for many of the area intersections. For this reason, some information regarding current traffic use patterns is not available. The full impact of these construction projects will not be known until construction is complete in 2020. For this reason, ATS collected traffic data only at locations which may still be reliable for comparison with data collected in this area in 2017. In September 2019 Abelin Traffic Services (ATS) collected turning movement count data at the intersections of Durston Road with Rosa Parkway and Laurel Parkway. ATS also obtained peak-hour turning movement count data from the 2017 Bozeman Transportation Master Plan for the intersections of Durston Road & Cottonwood Road. The raw traffic data is included in Appendix A of this report. Historic traffic data was also collected for Durston Road from the Montana Department of Transportation. The data for this location is presented in Table 1. Over the past eight years traffic volumes on Durston Road have increased at an average annual rate of 4%. Table 1 – Historic Traffic Data Location 2011 2012 2013 2014 2015 2016 2017 2018 Durston Road East of Cottonwood Road (#16-3A-046) 6,450 6,390 7,790 7,490 7,690 8,847 8,776 9,055 Road Network Improvements and Bozeman High School The new Bozeman High School will be located at the north end of Cottonwood Road adjacent to Oak Street. The school is scheduled to be open in the fall of 2020 and will ultimately serve up to 1,500 students. The updated traffic study prepared for the new High School in January 2018 forecasts the projected 2020 and 2035 traffic volume conditions on the surrounding road system with a variety of road network configurations. The traffic Boulder Creek Apartments Traffic Impact Study Bozeman, Montana Abelin Traffic Services 4 December, 2019 impact study also provides a separate analysis for the development of an extension of Cottonwood Road from Oak Street to Baxter Lane. The report suggests that the new High School will produce 960 AM peak-hour trips and 765 PM peak-hour trips. The traffic study indicates that the planned road improvements in this area will accommodate the traffic from the new High School and did not recommend any specific roadway improvements beyond those already assumed for this area. The assumed road improvements from the 2018 High School TIS include: • The expansion of Cottonwood Road to a 5-lane section from Durston Road to Oak Street. (Under Construction) • Widening Flanders Mill Road to an urban 2-lane section from Durston Road to Baxter Lane. (Completed) • The extension of Oak Street to a 4-lane section with center median from Ferguson Road to Cottonwood Road. (Under Construction) • Extending Ferguson Avenue from Baxter Lane to Oak Street. (Completed) • The installation of a traffic Signal at the Oak Street & Ferguson Avenue intersection. (Completed) • The installation of a modern roundabout at the intersection of Cottonwood Road and Oak Street. (Under Construction) The Boulder Creek Apartments project will likely be fully built-out before the new High School reaches full capacity in 5-10 years. Another important consideration regarding the traffic from the new High School is that the peak traffic generation periods for a high school generally fall outside of the peak traffic generation periods for a residential area, especially for the afternoon and evening peak travel periods. While the AM peak traffic periods can overlap, the peak traffic generation period in the afternoon for the High School will occur between the hours of 3:00 and 4:00. The High School will produce relatively little traffic during the evening peak traffic periods for the adjacent street network and residential areas which will occur between 5:00 and 6:00. Therefore, only the AM traffic generation from the High School was used for the traffic analysis for the Boulder Creek Apartments. Additional Developments The Boulder Creek residential, Westbrook, Rosa Apartments, and Nest Cottages projects are in a variety of stages of completion in the vicinity of the proposed Boulder Creek Apartments project. The Rosa Apartments have reached 60% completion (78 units remaining) and the Boulder Creek project has 20 duplex units which have yet to be constructed (40 total units). The Westbrook residential project has 20 lots which remain to be constructed. The Nest Cottages are also approved for construction in this area (47 Units). The traffic impacts from the remaining portions of these projects was included in the future traffic projections for this report. Boulder Creek Apartments Traffic Impact Study Bozeman, Montana Abelin Traffic Services 5 December, 2019 Level of Service Using the data collected for this project, ATS conducted a Level of Service (LOS) analysis at area intersections. This evaluation was conducted in accordance with the procedures outlined in the Transportation Research Board’s Highway Capacity Manual (HCM) - Special Report 209 and the Highway Capacity Software (HCS) version 7.8. Intersections are graded from A to F representing the average delay that a vehicle entering an intersection can expect. Typically, a LOS of C or better is considered acceptable for peak-hour conditions. Table 2 – 2019 Level of Service Summary AM Peak Hour PM Peak Hour Intersection Delay (Sec.) LOS Delay (Sec.) LOS Durston Road & Laurel Parkway 11.7 B 12.2 B Durston Road & Rosa Way* 13.5 B 13.8 C Durston Road & Cottonwood Road** 12.5 B 11.5 B *Northbound/Southbound LOS and Delay. **Based on 2017 Traffic Data. Table 2 shows the existing 2019 LOS for the AM and PM peak hours without the traffic from the proposed Boulder Creek Apartments development. This analysis included the planned roadway modifications which are currently underway at the intersection of Cottonwood Road and Durston Road. The existing intersections along Durston Road will operate within acceptable limits once the current road construction projects are completed in 2020. The intersection of Oak Street and Cottonwood Road will be constructed as a multi-lane roundabout with a total daily capacity of over 36,000 VPD. Based on current traffic volumes on the existing road network, the roundabout will operate at 10-20% of capacity when opened in 2020. No additional intersection modification are currently needed in this area to improve roadway capacity with the existing traffic loads. The LOS calculations are included in Appendix C of this report. D. PROPOSED DEVELOPMENT The development under consideration for this site includes six acres of land located between Oak Street and Durston Road which would be developed into a 112 unit residential apartment complex. The Boulder Creek Apartment will include 112 residential units split between eight apartment buildings. The site will include 248 off-street parking spaces. Access to the development would be from Abigale Lane to the west and Sherwood Way to the south. The Boulder Creek Apartments development is shown in Figure 2. It is expected that the project would be completed in 2021. Boulder Creek Apartments Traffic Impact Study Bozeman, Montana Abelin Traffic Services 6 December, 2019 Figure 2 – Proposed Development Boulder Creek Apartments Traffic Impact Study Bozeman, Montana Abelin Traffic Services 7 December, 2019 E. TRIP GENERATION AND ASSIGNMENT ATS performed a trip generation analysis to determine the anticipated future traffic volumes from the proposed development using the trip generation rates contained in Trip Generation (Institute of Transportation Engineers, Tenth Edition). These rates are the national standard and are based on the most current information available to planners. A vehicle “trip” is defined as any trip that either begins or ends at the development site. ATS determined that the critical traffic impacts on the intersections and roadways would occur during the weekday morning and evening peak hours. According to the ITE trip generation rates, at full build-out the development would produce 40 AM peak hour trips, 49 PM peak hour trips, and 609 daily trips. See Table 3 for detailed trip generation information. Table 3 - Trip Generation Rates Land Use Units AM Peak Hour Trip Ends per Unit Total AM Peak Hour Trip Ends PM Peak Hour Trip Ends per Unit Total PM Peak Hour Trip Ends Weekday Trip Ends per Unit Total Weekday Trip Ends Boulder Creek Apartments ITE #221 112 0.36 40 0.44 49 5.44 609 F. TRIP DISTRIBUTION The traffic distribution and assignment for the proposed subdivisions was based upon the existing ADT volumes along the adjacent roadways and project traffic volumes with the planned roadway improvements. The completion of the east/west Oak Street corridor and the north/south Cottonwood Road corridors will significantly change traffic patterns in this area and will increase the overall roadway network capacity. When completed in 2020 these roadway corridors will provide drivers with a variety of options for connecting to the existing road network to the east. The full impact of these changes will not be known until the network is in full operation, but it can be estimated that traffic from this area will distribute onto the surrounding road network as shown in Figure 4. G. TRAFFIC IMPACTS OUTSIDE OF THE DEVELOPMENT Using the trip generation and trip distribution numbers, ATS determined the future Level of Service for the area intersections. The anticipated intersection LOS with the Boulder Creek Apartments is shown in Table 3. These calculations are based on the projected model volumes included in Appendix B of this report and include remaining anticipated traffic from Boulder Creek subdivision (20 units), the Rosa Apartments project (78 units), Nest Cottages (47 units), and Westbrook (40 units). The future traffic volumes also include the projected future traffic from the new High School for the AM peak traffic period, which may overlap between these two land uses. Boulder Creek Apartments Traffic Impact Study Bozeman, Montana Abelin Traffic Services 8 December, 2019 Figure 4 – Trip Distribution Table 3 –Level of Service Summary With the Boulder Creek Apartments and New High School AM Peak Hour PM Peak Hour Intersection Delay (Sec.) LOS Delay (Sec.) LOS Durston Road & Laurel Parkeway 12.0 B 12.4 B Durston Road & Rosa Way* 16.6 C 14.2 B Durston Road & Cottonwood Road 23.4 C 11.8 B *Northbound/Southbound LOS and Delay. Table 3 indicates that the construction of the Boulder Creek Apartments will not cause any roadway capacity deficiencies on the surrounding road network. All roadways and intersections will continue to operate at an acceptable level of service through full build-out of these projects with the roadway improvement projects currently underway at the adjacent intersections. The roundabout at the intersection of Oak Street and Cottonwood Road will function at 30-40% of capacity with the proposed land uses in this area, including the new High School. The strong grid network planned for this portion of Bozeman will allow the distribution of traffic onto a variety of different major arterial roadways. Traffic entering and exiting the nearby residential areas will be able to choose the best available routes to gain access to the nearby controlled intersection along Cottonwood Road at Durston Road and Oak Street. The planned 25% 25% 20% Durston Road Development site Cottonwood Road Laurel Parkway Sherwood Way Oak Street 30% Boulder Creek Apartments Traffic Impact Study Bozeman, Montana Abelin Traffic Services 9 December, 2019 future road network for this area will easily accommodate the new High School and the adjacent residential developments, including the Boulder Creek Apartments. H. Long Range Traffic Projections It is anticipated that Cottonwood Road will be extended to the north to Baxter Road within the next 15 years. This new road connection will significantly alter roadway traffic patterns throughout this area. The magnitude of these traffic volume changes require a regional traffic model to evaluate accurately. The 2017 Bozeman Transportation Master Plan projects traffic conditions on roadways throughout Bozeman through 2040 and takes into account all anticipated land development projects which are expected to occur in this area of Bozeman over the next 25 years. The 2017 Bozeman Transportation Master Plan suggests that the intersection of Durston Road and Cottonwood Road will function at LOS F/E by 2040 even with a full expansion of Cottonwood Road to a five-lane collector road from Huffine Lane to Baxter Road. However, the 2017 Bozeman Transportation Master Plan also suggests that the roadways in this area will operate well within their functional capacities through 2040 (V/C of 0.43 to 0.79). Therefore, it is likely that the LOS issues projected by 2040 at this location will be correctable with minor intersection improvements which will be identified in the future when exact traffic volumes and patterns are known. The multi-lane roundabout at the intersection of Cottonwood Road and Oak Street will likely operate at 60-70% of capacity by 2040. The City’s plan to improve all of Cottonwood Road to a five-lane facility is appropriate based on the projected traffic volumes for this area. No additional roadway improvements specific to the Nest Cottages would be necessary to address future traffic volumes. I. IMPACT SUMMARY & RECOMMENDATIONS As proposed, the Boulder Creek Apartments will not create any roadway capacity problems along Durston Road or Oak Street. The current roadway construction projects along Oak Street and Cottonwood Road will significantly alter traffic patterns in this area and will increase the overall roadway network capacity. All nearby intersections will continue to function at acceptable levels of service with the Boulder Creek Apartments and the additional anticipated developments in this area, including the new Bozeman High School. Long-range traffic volume growth in this area suggests the need for widening Cottonwood Road to a five-lane facility. This need was identified in the 2017 Bozeman Transportation Master Plan and implementation of roadway widening is currently being planned by the City of Bozeman.