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HomeMy WebLinkAboutApp. F. - Traffic Impact Study 09-24-2019Norton East Ranch Phase 5 Traffic Impact Study Bozeman, Montana Abelin Traffic Services 1 April, 2018 Norton East Ranch Phase 5 Residential Subdivision Traffic Impact Study Bozeman, Montana A. EXECUTIVE SUMMARY The Norton East Ranch Subdivision Phase 5 is a 79.3-acre development located at the west end of Babcock Street in Bozeman, MT. The project would include up to 139 new residential units. It is likely that a traffic signal will eventually be needed at the intersection of Cottonwood Road and Babcock Street to meet future traffic demands with the construction of the Bozeman High School and the other planned developments in this area, but it is not known exactly when traffic signal installation warrants will be met at this location. It is recommended that the intersection be prepared for the installation of a traffic signal and that traffic counts be performed after the new High School is opened in 2020 to determine when a traffic signal will be warranted. The City of Bozeman should plan for the eventual need to install a traffic signal or roundabout at the intersection of Durston Road and Laurel Parkway to meet traffic demands past 2030. B. PROJECT DESCRIPTION This document studies the possible effects on the surrounding road system from a proposed residential subdivision located west of Cottonwood Road between Huffine Lane and Durston Road in Bozeman, Montana. The document also identifies any traffic mitigation efforts that the development may require. The site is located at the western end of Babcock Street. The project would be developed to include up to 139 new residential units on 79.3 acres of property. Based on the City of Bozeman Subdivision Regulations, the developers must study all effected intersections within ½ mile of the proposed development, which includes the intersections of Cottonwood Road with Durston Road and Babcock Street, and the intersection of Laurel Parkway with Durston Road. Although the intersection of Fallon Street and Cottonwood Road is technically more than 0.5 miles from the Norton Phase 5 development, it was analyzed in this report because it is important for the traffic operation of the rest of the Norton East Ranch development phases. C. EXISTING CONDITIONS The proposed development property currently consists of a 79.3-acre parcel of undeveloped land located at the west end of Babcock Street, north of the Norton East Ranch Phases 1-4, and just south of the Lakes at Valley West subdivision. The topography in this area is flat. See Figure 1 for a location map of the proposed development. Norton East Ranch Phase 5 Traffic Impact Study Bozeman, Montana Abelin Traffic Services 2 April, 2018 Figure 1- Proposed Development Site Adjacent Roadways Cottonwood Road is a north/south principal arterial street. North of Huffine Lane the road has experienced a significant amount of new development over the past ten years including a variety of commercial spaces, offices, apartments, and residential units. North of Huffine Lane the road has a five-lane cross-section to West Babcock Street. North of West Babcock Street the road narrows to a two-lane cross section. The posted speed limit is 35 MPH. The intersection of Cottonwood Road and Durston Road Lane is currently signalized. 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 9,300 Vehicles Per Day (VPD) in 2016. West Babcock Street is an east-west, two-way, two-lane collector which extends west of Main Proposed Development Site = Study Intersection Norton East Ranch Phase 5 Traffic Impact Study Bozeman, Montana Abelin Traffic Services 3 April, 2018 Street. West of Cottonwood Road the street has a paved width of 44 feet with a center two- way left-turn lane and bike lanes. The posted speed limit is 30 MPH. The road is controlled with STOP signs at the intersection with Cottonwood Road. Traffic data collected in 2016 by MDT indicates that West Babcock Street currently carries 1,000 VPD west of Cottonwood Road. Fallon Street is a two-way, paved east/west local road that provides access to existing developments north of Huffine Lane. The road has a paved width of 32 feet and has a posted speed limit of 25 MPH. Fallon Street is controlled by STOP signs at the intersection with Cottonwood Road. All other cross-streets on Fallon Street are controlled by STOP signs on the north/south approaches. Traffic Counts The traffic data used for this report was collected on the surrounding road system by ATS in the summer of 2017 for other ongoing development projects in this area. The collected data includes turning movement counts at the intersections of Cottonwood Road with Durston Road, Babcock Street, and Fallon and at the intersection of Babcock Street with Laurel Parkway. The raw traffic data is included in Appendix A of this report. Historic traffic data was also collected for Huffine Lane and Cottonwood Road from the Montana Department of Transportation. The data for this location is presented in Table 1. Traffic volumes along Huffine Lane decreased between 2008 and 2010 but are now experiencing high rates of growth. It is likely that traffic volumes along Huffine Lane will continue to increase. Traffic volumes on Cottonwood Road have increased significantly in the past three years. Table 1 – Huffine Lane Historic Average Daily Traffic Data Location 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Huffine Lane east of Cottonwood Road #16-3A-026 19,835 19,675 18,900 21,270 21,480 21,660 22,670 20,370 24,406 27,643 Huffine Lane west of Cottonwood Road #16-3A-013 22,070 21,850 20,130 20,790 21,240 22,260 23,000 19,886 24,836 27,044 Cottonwood Road south of Huffine Lane #16-3A-019 2,720 2,760 2,920 2,930 2,990 3,120 3,320 4,043 6,549 5,105 Additional Developments Phase 5 of the Norton East Ranch project follows Phases 1, 2, 3, and 4. Phases 1 and 2 are currently built out and Phase 3 will be completed in the fall of 2019. Construction on Phase 4 will begin in the fall of 2018. Approximately 1/3 of the houses developed for Phase 3 (106 Norton East Ranch Phase 5 Traffic Impact Study Bozeman, Montana Abelin Traffic Services 4 April, 2018 units total) were constructed and occupied when the traffic data was collected for this project in the summer of 2017. Additional traffic taken into account for this analysis includes the J&D Family Development which is currently under construction just east of the Norton East Ranch site. Many of the commercial lots within this development have already been constructed. This development also has plans for the development of 40-residential lots to the west of the commercial area but it is not known when the development of those lots may occur. Additional projects that were accounted for with the traffic projects include which were not constructed when the traffic counts were performed in this area in the summer of 2017 include the unbuilt portion of Phase 3 of the Norton Development (70 units), Phase 4 of the Norton Development (105 units) the Boulder Creek subdivision north of Durston Road (111 units), the Rosa Apartments project north of Durston Road (194 units), the Valley West subdivision north of Durston Road (55 units), and Lakes and Valley West project (300 units). The traffic studies performed for these developments were reviewed and the relevant traffic projections from each project was applied to the future traffic projections in this report. New Bozeman High School The new Bozeman High School is currently in the planning stages and 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 impact study also provides a separate analysis for the development of an extension of Cottonwood Road north from Oak Street to Baxter Lane, although it is not known when or if this road extension will be in place by 2035. 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 report does not provide specific dates for when the planned road network improvements may be implemented. The assumed road improvements from the 2018 High School traffic study include: • The expansion of Cottonwood Road to a 5-lane section from Durston Road to Oak Street. • Widening Flanders Mill Road to an urban 2-lane section from Durston Road to Baxter Lane. Norton East Ranch Phase 5 Traffic Impact Study Bozeman, Montana Abelin Traffic Services 5 April, 2018 • The extension of Oak Street to a 4-lane section with center median from Ferguson Road to Cottonwood Road. • Extending Ferguson Avenue from Baxter Lane to Oak Street. • The installation of a traffic Signal at the Oak Street & Ferguson Avenue intersection. • The installation of a modern roundabout at the intersection of Cottonwood Road and Oak Street. One important consideration regarding the traffic from the new High School is the fact that the peak traffic periods for traffic generation from 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. The peak traffic generation period in the afternoon for the High School will occur between the hours of 3:00 and 4:00 and 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, no traffic projections from the new High School were used for the PM peak conditions analysis in this report. The morning trip generation for the High School was included in the traffic projections as this traffic does generally overlap with morning residential traffic. 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 7.2. 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 shows the existing 2017 LOS for the AM and PM peak hours without the traffic from the proposed developments. The LOS calculations are included in Appendix C. The table shows that the existing intersections along Cottonwood Road are all currently operating within acceptable limits. The four-way STOP controlled intersection at Laurel Parkway is also functioning with acceptable levels of delay. The recent road widening has provided ample roadway capacity for the existing traffic volumes within the area. Norton East Ranch Phase 5 Traffic Impact Study Bozeman, Montana Abelin Traffic Services 6 April, 2018 Table 2 – 2017 Level of Service Summary AM Peak Hour PM Peak Hour Intersection Delay (Sec.) LOS Delay (Sec.) LOS Laurel Parkway & Durston Road 11.0 B 11.9 B Cottonwood Road & Duston Road 17.9 B 16.1 B Cottonwood Road & Babcock Street* 11.7/11.5 B/B 14.0/12.2 B/B Cottonwood Road & Fallon Street* 9.8/11.6 A/B 13.4/15.6 B/C *Northbound/Southbound or Westbound/Eastbound Side Street LOS and Delay D. PROPOSED DEVELOPMENT The development currently under consideration for this site includes 79.3 acres of land located at the west end of Babcock Street which would be developed into a residential. Phase 5 of this project would include 139 single-family residential units. The project would also include a connection to the north to Durston along Laurel Parkway through the Lakes at Valley West Subdivision. Development of the property would begin in 2019 and would be completed in 2020. The Norton East Ranch Subdivision Phase 5 development is shown in Figure 2. 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, Seventh 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 developments would produce 107 AM peak hour trips, 139 PM peak hour trips, and 1,323 daily trips. See Table 3 for detailed trip generation information. Norton East Ranch Phase 5 Traffic Impact Study Bozeman, Montana Abelin Traffic Services 7 April, 2018 Figure 2 – Proposed Norton East Ranch Phase 5 Development Norton East Ranch Phase 5 Traffic Impact Study Bozeman, Montana Abelin Traffic Services 8 April, 2018 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 Single Family Residential ITE #210 139 Units 0.75 107 1.00 139 9.52 1,323 The other projects which were accounted for in the traffic modeling include the unoccupied units in Norton East Ranch Phase 3, Phase 4 of the Norton East Ranch development, the Lakes at Valley West project, the Boulder Creek subdivision north of Durston Road, the Rosa Apartments project north of Durston Road, and the Valley West subdivision north of Durston Road. The analysis also include the projected traffic from the new High School for AM traffic conditions only as described in Section C. The trip generation from these projects is shown in Table 4. This data was obtained from the traffic impact studies prepared for each of these projects. Table 4 – Additional Development Trip Generation Land Use Units Total AM Peak Hour Trip Ends Total PM Peak Hour Trip Ends Total Weekday Trip Ends Norton Ranch Phases 3 Undeveloped 70 53 70 666 Norton Ranch Phases 4 Residential 105 56 69 724 Norton Ranch Phases 4 Commercial 5.8 Acres 190 97 864 Boulder Creek Subdivision 111 83 111 1,057 Rosa Apartments 194 99 120 1,290 Nest Cottages 47 35 47 447 Valley West Subdivision 55 41 55 524 Lakes at Valley West Subdivision 300 177 221 2,310 J&D Family Residential 40 30 40 381 J&D Family Commercial 4.7 Acres 89 79 704 TOTAL 853 909 8,967 *Remaining unbuilt/unoccupied units from Phase 3. Norton East Ranch Phase 5 Traffic Impact Study Bozeman, Montana Abelin Traffic Services 9 April, 2018 F. TRIP DISTRIBUTION The traffic distribution and assignment for the proposed subdivision was based upon the existing ADT volumes along the adjacent roadways and the peak-hour turning volumes. The new connection to Laurel Parkway will draw a significant amount of traffic from all five phases of the Norton Ranch development due to its direct access onto Durston Road. It is also expected that some traffic from the Lakes at Valley West subdivision will be redirected south through the Norton East Ranch project to avoid Durston Road. Traffic is expected to distribute onto the surrounding road network as shown on Figure 3. Figure 3 – Trip Distribution 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 Norton East Ranch Phase 5 is shown in Table 5. The future traffic modeling includes the projected traffic volumes from the undeveloped lots on Phases 3 and 4 of the Norton Ranch Project plus the other projects described in Section E of this report including the AM traffic from the new Bozeman High School. The calculations also include the planned widening project on Cottonwood Road north of Babcock Co t t o n w o o d R o a d 5% Babcock Street 5% Proposed Development Site Fallon Street Durston Road 25% 10% 5% 15% La u r e l P a r k w a y 35% Norton East Ranch Phase 5 Traffic Impact Study Bozeman, Montana Abelin Traffic Services 10 April, 2018 Street. The traffic volume calculations are included in Appendix B of this report. Table 5 indicates with that with the anticipated construction planned in this area including the Norton East Ranch and the new Bozeman High School, the intersections of Cottonwood Road with Babcock Street and Fallon Street may fall to LOS D. This effect will likely occur with or without the traffic from Phase 5 of the Norton East Ranch Subdivision and is largely due to the projected traffic from the Bozeman High School during the morning peak commute period. The eventual need to signalize the intersection of Cottonwood Road and Babcock Street was identified in 2017 Bozeman Transportation Master Plan. If a traffic signal was installed at Babcock Street it is likely that the intersection would draw traffic away from Fallon Street and eliminate the need for traffic control improvements on Fallon Street. Although the intersection of Babcock Street with Cottonwood Road is expected to experience a poor level of service at full build-out of the developments in this area and the Bozeman High School, it is not knows exactly when the intersection of Babcock Street will meet warrants for traffic signal installation. A poor level of service does not necessarily mean that any specific traffic signal installation warrants are met as defined by the Manual on Uniform Traffic Control Devices. It is not likely that any signal warrants will be met until after the High School is opened in 2020. In this instance it may be desirable to prepare the intersection for the installation of a traffic signal and perform additional traffic counts after the new High School is opened in 2020 to determine when traffic signal warrants may be met. Table 5 –Future Level of Service Summary AM Peak Hour PM Peak Hour Intersection Delay (Sec.) LOS Delay (Sec.) LOS Laurel Parkway & Durston Road 16.4 C 16.1 C Cottonwood Road & Durston Road 20.1 C 12.8 B Cottonwood Road & Babcock Street* 24.6/28.5 C/D 17.7/17.3 C/C Cottonwood Road & Fallon Street* 20.8/27.7 C/D 19.5/24.3 C/C *Northbound/Southbound or Westbound/Eastbound Side Street LOS and Delay Long Range Traffic Projections It is anticipated that Cottonwood Road will be extended to the north to Baxter Road and Oak Street will be extended past Cottonwood Road within the next 15 years. These new road connections 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 Norton East Ranch Phase 5 Traffic Impact Study Bozeman, Montana Abelin Traffic Services 11 April, 2018 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 Bozeman Transportation Master Plan suggests that traffic volumes on Cottonwood Road will increase to 26,000 VPD and the V/C on Cottonwood Road will be 0.8. The Bozeman Transportation Master Plan anticipated that a traffic signal will be constructed at the intersection of Cottonwood Road and Babcock Street by 2040 and that the intersection will function at LOS C/D once signalized. In order to evaluate the 15-year traffic volume projections for this area ATS reviewed the 2040 traffic volumes from the Bozeman Transportation Master Plan and scaled the anticipated traffic volume growth to likely 2033 conditions using an overall traffic volume growth rate of 160%. This growth factor was applied on top of the projected traffic volumes calculated for the Norton Ranch Phase 5 development. The results of this analysis suggest that both the intersection of Cottonwood Road and Babcock Street and Cottonwood Road and Fallon Street will experience LOS conditions of E to F by 2033. The intersection of Durston Road with Laurel Parkway will also likely operate at LOS F by 2033 with the current four-way STOP control configuration and may require the installation of a traffic signal or roundabout to improve operations. Improvements to this intersection should be performed when traffic volume warrants are met, which will depend heavily on how and when other road connections in this area are made. H. IMPACT SUMMARY & RECOMMENDATIONS It is likely that a traffic signal will eventually be needed at the intersection of Cottonwood Road and Babcock Street to meet future traffic demands with the construction of the Bozeman High School and the other planned developments in this area, but it is not known exactly when traffic signal installation warrants will be met at this location. It is recommended that the intersection be prepared for the installation of a traffic signal and that traffic counts be performed after the new High School is opened in 2020 to determine when a traffic signal will be warranted. The City of Bozeman should plan for the eventual need to install a traffic signal or roundabout at the intersection of Durston Road and Laurel Parkway to meet traffic demands past 2030.