Loading...
HomeMy WebLinkAbout007.04 - TIS_Simulation_Response May 31, 2024 Kyle Scarr, PE TD&H Engineering 234 E Babcock Street, Suite 3 Bozeman, MT 59715 Reference: 8 Aspen Development TIS, Bozeman, MT Project No. 23505 Dear Kyle: The purpose of this letter is to provide a response to comments received from the City of Bozeman regarding the 8 Aspen Development TIS (May 2024) for the proposed residential and commercial development in Bozeman, Montana. Adjacent Development Trips It was requested that trips from one adjacent development on the southeast corner of the North 7th Avenue/West Aspen Street intersection be included in the future analysis scenarios. These trips were added to the analysis assuming no access restrictions at the North 7th Avenue/West Aspen Street intersection and the capacity results for each of the Full Buildout (2026) and Future (2038) scenarios are described in the following paragraphs. Current full buildout planning is estimated at the end of 2026. Updated capacity tables are also attached. Full Buildout (2026) Analysis With additional adjacent development trips added, capacity results in the Full Buildout (2026) scenario are very similar to the original analysis, with small increases to approach delay at most intersections. Level of service (LOS) is projected to change from LOS C to LOS D on the northbound approach at the North 11th Avenue/Durston Road intersection and the southbound approach at the North 7th Avenue/West Peach Street intersection during the PM peak hour, but average delay on each approach would only increase by up to 1.0 second, meaning that the previous delay values were already very close to the LOS C cutoff value. Future (2038) Analysis With the additional adjacent development trips added in the Future (2038) scenario, delay is projected to change slightly on approaches that were already projected to operate at LOS D or lower. At the North 7th Avenue/West Aspen Street intersection, delay on the eastbound approach (8 Aspen Development side) is similar to the previous analysis but delay on the westbound approach (adjacent development side) is projected to deteriorate with the additional trips added, changing from LOS B to LOS F during the AM peak hour and increasing exponentially during the PM peak hour. Due to the extreme delay values projected in the PM peak hour, the overall intersection delay is projected to change to LOS D with a delay value just less than 2.0 seconds above the LOS C cutoff value. Kyle Scarr, PE May 31, 2024 Page 2 Conclusions Previous analyses performed and conclusions made regarding implementation of access restrictions at West Juniper Street and West Aspen Street are not likely to be substantially impacted with the addition of trips from the anticipated development on the southeast corner of the North 7th Avenue/West Aspen Street intersection. As noted in the 8 Aspen Development TIS (May 2024), trip generation for the site was estimated completely as vehicle trips with no multimodal or transit reductions to provide a conservatory worst-case impact scenario. Adjacent transit stops, multimodal facilities, and on-site parking for approximately 50% of the site will all reduce the vehicle trip dependency for the site. Simulation Analysis Comments received from the City of Bozeman also requested a simulation analysis of the North 7th Avenue corridor between West Peach Street and West Juniper Street to evaluate capacity, queuing, and gaps. The traffic simulation analysis was performed using SimTraffic, Version 12, which generally showed improved results for minor approaches as compared to the HCM-based Synchro results. The simulation results indicate that “real-world” operations may provide increased gaps for access from West Juniper Street and West Aspen Street due to the signal timing coordination plan in the corridor. Synchro calculations assume random arrivals on all approaches; however, the simulation shows that platoons released by each phase of the adjacent traffic signals may provide adequate gaps for vehicles accessing North 7th Avenue. Signal operations should be monitored in the field by MDT and the City to confirm these assumptions and determine if minor approach vehicles experience excessive delay even with gaps provided by the signal timing plans. MDT has a current safety project along North 7th Avenue with plans to modify ADA, geometrics, and signal upgrades at the adjacent corridor signals in 2025. Review of corridor operations and signal timings should be reviewed as part of the MDT project. Delay outputs from simulation analyses cannot be directly compared to average approach delay and LOS calculated using HCM methods. However, SimTraffic provides a value of total delay per vehicle, which is quite similar. This value was used to evaluate operations in the simulation analysis, and simulation runs were also performed with Existing Conditions (2023) volumes to provide an additional point of comparison. With simulation, tot al delay per vehicle at West Aspen Street and West Juniper Street is approximately 40 to 50 percent of the average delay calculated using HCM methods for Existing Conditions (2023), with values in what would be considered the LOS C or better range. Detailed descriptions of the simulation analysis for each future scenario are provided in the following paragraphs. Full Buildout (2026) Simulation Analysis In the Full Buildout (2026) scenario, the simulation results showed total delay values per vehicle that are approximately 30 to 50 percent of the HCM delay values (LOS C range) on West Juniper Street and West Aspen Street where the HCM results were LOS D or lower. When observing the simulation, vehicles on West Juniper Street and West Aspen Street were able to enter the mainline North 7th Avenue due to the signals at West Tamarack Street and West Peach Street providing frequent gaps. Projected 95th percentile simulation queues on North 7th Avenue were shown to reach up to two vehicles at both West Juniper Street and West Aspen Street, which fits within the existing turn lane geometry. Kyle Scarr, PE May 31, 2024 Page 3 Future (2038) Simulation Analysis Simulation results with Future (2038) volumes were also much lower than HCM results at the West Juniper Street and West Aspen Street intersections. At West Juniper Street, simulation delay is between 20 and 35 percent of HCM delay on the eastbound approach, which was LOS F. Projected 95th percentile queues were shown to reach two vehicles on North 7th Avenue. At West Aspen Street, simulation delay is 35 to 50 percent of HCM delay during the AM peak hour and only 5 to 15 percent of HCM delay in the PM peak hour. This is due to the exponentially increasing delay that was projected with PM volumes. Queues of up to three vehicles are projected on North 7th Avenue at West Aspen Street, which still fits within the available geometry. The total delay values shown in the simulation at both intersections would still equate to LOS between D and F on those approaches, but the actual delay experienced is projected to be much lower, and overall intersection delay is in the LOS A range. Corridor Simulation Analysis Total corridor delay is projected to increase by up to 20 percent between Existing Conditions (2023) and Full Buildout (2026) while total travel time is projected to increase by up to 10 percent. Between the Full Buildout (2026) and Future (2038) scenarios, total corridor is projected to increase by a factor of 2.0 while total travel time would increase by up to 4.7 times in the northbound direction during the PM peak hour. All other directions and peaks would only increase travel time by just over 20 percent. Conclusions All of the above results are highly dependent on the signal timing and coordination plan through the corridor. Lower or improved results could be achieved through changes to signal timing and coordination offsets, and it’s likely that total delay on approaches and through the corridor may vary widely depending on these factors. However, in general the simulation results showed improved operations when compared to HCM analysis due to the simulation’s ability to evaluate the network as a whole and account for traffic progression through a corridor, which is likely more representative of field conditions. Recommendations Based on the above analysis, simulation results indicate that access to North 7th Avenue from both West Juniper Street and West Aspen Street is likely to operate with less delay than originally projected using HCM methods. In the Full Buildout (2026) scenario, delay from the minor approaches is likely to be in the LOS C range, but in the Future (2038) scenario, minor approach delay is still projected to reach values consistent with LOS F. Full coordination of the traffic signals in the North 7th Avenue corridor to include the West Peach Street intersection would likely provide further improvements to operations and available gaps. A traffic signal at the West Aspen Street intersection would provide controlled access to the North 7th Avenue corridor and alleviate access and delay concerns associated with left-turning vehicles onto North 7th Avenue. A traffic signal would likely not be required from an overall delay standpoint in the Full Buildout (2026) scenario but should be considered by 2038. A traffic signal may not be Kyle Scarr, PE May 31, 2024 Page 4 preferred at this intersection by MDT due to its proximity (~360 feet) to the existing signal at the North 7th Avenue/West Tamarack Street intersection, but it may be beneficial to provide controlled access onto North 7th Avenue for existing and proposed adjacent developments. The spacing between West Aspen Street and West Tamarack Street is similar to traffic signal spacing in the downtown Bozeman core area. If a traffic signal is not deemed appropriate at this intersection, access control at West Aspen Street should be considered to prohibit left turns onto North 7th Avenue. Additionally, if a traffic signal is not installed at the North 7th Avenue/West Aspen Street intersection, a pedestrian actuated crosswalk should be installed across the north leg to include an RRFB and median refuge area. The median refuge area would require that the existing southbound left-turn lane be removed and therefore southbound left turns should be prohibited with this configuration. If you have any questions or concerns, please feel free to contact me at 406-922-4326 or astoltzfus@sandersonstewart.com. Sincerely, Audrey Stoltzfus, PE, RSP1 Project Engineer ARS/jhs Enc: Capacity Tables P:\23505_8_Aspen_Bozeman_TIS_5.31.2024 Future Conditions Capacity Calculation Summary Avg Delay (s/veh) LOS 95th % Queue (veh) Avg Delay (s/veh) LOS 95th % Queue (veh) EB 49.1E1 54.4F1 WB 14.1B1 16.6C1 NB 0.2A0 0.0A0 SB 0.3A1 0.3A1 Intersection 0.9A --1.0A -- WB 54.4D3 52.6D7 NB 3.7A7 8.7A 14 SB 2.3A9 5.2A7 Intersection 6.4A --13.0B -- EB 30.2D2 51.3F3 WB 10.4B0 54.2F2 NB 0.5A1 1.0A1 SB 0.1A0 0.2A1 Intersection 1.6A --2.8A -- EB 0.0A0 0.0A0 WB 2.2A1 1.2A1 NB 18.5C2 25.2D4 Intersection 3.2A --5.5A -- EB 0.0A0 0.0A0 WB 0.0A0 0.0A0 NB 13.9B0 15.6C1 Intersection 0.0A --0.1A -- EB 47.8D 26 59.1E 24 WB 49.7D 17 79.5E 28 NB 33.3C 10 58.8E 23 SB 29.2C 16 35.8D 15 Intersection 37.0D --54.1D -- Signalized North 7th Avenue & West Tamarack Street Intersection Control Two-Way Stop-Control (EB/WB) Intersection Approach Full Buildout (2026) AM Peak PM Peak Intersection Control Two-Way Stop-Control (EB/WB) North 8th Avenue & Durston Road Intersection Control Signalized North 7th Avenue & West Peach Street North 7th Avenue & West Aspen Street Intersection Control One-Way Stop-Control (NB) North 11th Avenue & Durston Road Intersection Control One-Way Stop-Control (NB) North 7th Avenue & West Juniper Street Intersection Control Future Conditions Capacity Calculation Summary Avg Delay (s/veh) LOS 95th % Queue (veh) Avg Delay (s/veh) LOS 95th % Queue (veh) EB 104.7F1 156.6F2 WB 18.2C1 23.5C1 NB 0.2A1 0.0A0 SB 0.3A1 0.3A1 Intersection 1.1A --1.7A -- WB 53.0D4 49.2D9 NB 4.6A9 13.5B 24 SB 3.2A 12 8.4A 10 Intersection 7.1A --16.0B -- EB 71.1F4 245.5F6 WB 52.8F2 874.8F9 NB 0.5A1 1.0A1 SB 0.1A1 0.5A1 Intersection 3.5A --26.6D -- EB 0.0A0 0.0A0 WB 2.5A1 1.3A1 NB 29.0D3 78.9F 10 Intersection 4.6A --16.1C -- EB 0.0A0 0.0A0 WB 0.0A0 0.0A0 NB 16.0C0 18.7C1 Intersection 0.0A --0.1A -- EB 103.4F 37 88.7F 33 WB 74.0E 24 205.3F 38 NB 45.1D 13 129.1F 33 SB 46.0D 23 47.0D 20 Intersection 62.8E --103.9F -- Intersection Control Two-Way Stop-Control (EB/WB) Intersection Approach Future (2038) AM Peak PM Peak North 7th Avenue & West Juniper Street Intersection Control Signalized North 7th Avenue & West Tamarack Street Intersection Control Two-Way Stop-Control (EB/WB) North 8th Avenue & Durston Road Intersection Control Signalized North 7th Avenue & West Peach Street North 7th Avenue & West Aspen Street Intersection Control One-Way Stop-Control (NB) North 11th Avenue & Durston Road Intersection Control One-Way Stop-Control (NB) Existing Conditions Simulation Summary - Uncoordinated Total Delay (s/veh) 95th % Queue (veh) Total Delay (s/veh) 95th % Queue (veh) EB 21.81 17.93 WB 6.02 8.63 NB 0.81 1.21 SB 0.62 0.62 Intersection 0.8 --1.2 -- WB 22.54 27.26 NB 2.13 4.78 SB 2.14 4.55 Intersection 3.5 --7.6 -- EB 15.81 12.73 WB 1.51 15.72 NB 2.01 3.72 SB 1.01 1.42 Intersection 1.4 --3.0 -- EB 57.5 17 77.9 16 WB 42.5 12 77.5 23 NB 29.69 43.6 18 SB 26.8 12 32.4 13 Intersection 36.6 --51.4 -- Intersection Approach Existing (2023) AM Peak PM Peak Intersection Control Two-Way Stop-Control (EB/WB) North 7th Avenue & West Juniper Street Intersection Control Signalized North 7th Avenue & West Tamarack Street Intersection Control Two-Way Stop-Control (EB/WB) North 7th Avenue & West Aspen Street North 7th Avenue & West Peach Street Intersection Control Signalized Future Conditions Simulation Summary - Uncoordinated Total Delay (s/veh) 95th % Queue (veh) Total Delay (s/veh) 95th % Queue (veh) EB 17.52 18.53 WB 5.92 9.63 NB 1.02 1.11 SB 0.62 0.72 Intersection 1.0 --1.3 -- WB 23.44 29.17 NB 2.94 4.36 SB 2.34 5.25 Intersection 4.0 --8.0 -- EB 14.13 18.43 WB 1.71 15.43 NB 2.52 4.33 SB 1.11 1.62 Intersection 2.2 --3.7 -- EB 68.9 16 96.9 14 WB 45.6 13 125.4 30 NB 34.89 52.4 20 SB 30.0 14 33.8 14 Intersection 42.1 --64.6 -- North 7th Avenue & West Juniper Street Intersection Control Full Buildout (2026) AM Peak PM Peak Intersection Control Two-Way Stop-Control (EB/WB) Intersection Approach Signalized North 7th Avenue & West Tamarack Street Intersection Control Two-Way Stop-Control (EB/WB) North 7th Avenue & West Aspen Street Intersection Control Signalized North 7th Avenue & West Peach Street Future Conditions Simulation Summary - Uncoordinated Total Delay (s/veh) 95th % Queue (veh) Total Delay (s/veh) 95th % Queue (veh) EB 36.72 33.03 WB 7.82 14.43 NB 1.21 1.42 SB 1.02 0.92 Intersection 1.3 --1.6 -- WB 23.65 31.69 NB 3.85 6.29 SB 3.86 6.06 Intersection 5.2 --9.7 -- EB 26.14 34.74 WB 25.73 60.65 NB 3.22 5.33 SB 1.62 2.13 Intersection 3.4 --5.9 -- EB 97.6 14 104.0 14 WB 74.4 23 202.9 26 NB 40.6 13 113.9 20 SB 47.2 23 48.6 23 Intersection 58.6 --98.4 -- North 7th Avenue & West Peach Street Intersection Control Signalized North 7th Avenue & West Aspen Street North 7th Avenue & West Tamarack Street Intersection Control Two-Way Stop-Control (EB/WB) North 7th Avenue & West Juniper Street Intersection Control Signalized AM Peak PM Peak Intersection Approach Full Buildout (2038) Intersection Control Two-Way Stop-Control (EB/WB)