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Item 6B - Traffic StudyMEMORANDUM To:Sandy Endy, P.E. Development Engineer – City of Southlake From: Douglas M Arnold, P.E. Kimley-Horn and Associates, Inc. Date: April 9, 2024 Re:Traffic Study for Willowtree Gardens / The Overlook Proposed Residential and Office Development Southlake, Texas PURPOSE This memorandum serves as a traffic study for a proposed single-family and office development located on the west side of North Carroll Avenue, north of Southlake Boulevard, in the City of Southlake, Texas. The development is anticipated to include 23 detached single-family dwelling units and 23,000 square feet of general office space.Exhibit 1 (attached) provides the general site location of the proposed development. The following traffic assessment will include the following: existing and proposed roadway characteristics, proposed development characteristics, need for auxiliary lanes, access spacing, sight distance, and driveway intersection delay and level of service (LOS). EXISTING TRANSPORTATION SYSTEM North Carroll Avenue is a four-lane divided Arterial roadway with a posted speed of 30 mph. North Carrol Avenue provides access for development traffic to Southlake Boulevard (FM 1709) to the south and SH 114 to the north. Adjacent to the development, there is a raised median along North Carroll Avenue. This section of North Carroll Avenue is built out to its ultimate cross section. Southlake Boulevard (FM 1709) is a six-lane divided Arterial with a posted speed of 45 mph. Southlake Boulevard provides access to Kimball Avenue and SH 114 to the east, and other City thoroughfares to the west. Based on recent (2019) TxDOT traffic count data, the daily volumes along North Carroll Avenue, north of Southlake Boulevard, is approximately 19,900 vehicles per day. A peak hour traffic count was performed during the weekday PM peak hour at North Carroll Avenue & Main Street on Tuesday, February 20, 2024; based on this traffic count, the NB volume was 860 vehicles per hour and the SB volume was 860 vehicles per hour. Exhibit 2 (attached) provides the weekday PM peak hour turning movement counts at North Carroll Avenue & Main Street. 04/09/2024 Page 2 PROPOSED DEVELOPMENT INFORMATION The proposed development sits on an undeveloped plot and as such generates no traffic. The development’s concept plan (attached) includes 23 single-family detached housing dwellings and a +/- 23,000 square-foot general office building. A total of 5 of the 23 residential units are proposed to be outside of the gated residential area with primary access via Cross Lane (that traffic will not access North Carroll Avenue). Site Access As previously mentioned, the subject property is located on the west side of North Carroll Avenue. To the north of the development, there is a developed residential neighborhood, and to the south is an undeveloped parcel and an existing medical office building, both under separate ownership. West of the subject property is a residential neighborhood; based on feedback from the neighborhood and the Planning & Zoning committee; there will be no connections this development to that neighborhood via Cross Lane. In the future, cross access will be provided to the adjacent properties. Based on the development concept plan, there are two driveways proposed to serve the development. The southern driveway, located approximately 600 feet north of Southlake Blvd, will primarily serve the general office development. The northern driveway, located approximately 180 feet north of the southern driveway and approximately 350 feet south of Ownby Ln, will primarily serve the homes. Since there is a raised median along North Carroll Avenue spanning the entire frontage of the subject property, the development is proposing to install a northbound left-turn lane to serve the northern site driveway. An analysis of this proposed improvement will be provided later in the memo. The developer is looking to get conceptual approval of the left-turn lane as part of this traffic study, with detailed engineering plans to come as part of the site plan process. A photolog is provided as an attachment that shows the line of sight for the proposed northbound left-turn lane; based on field observations, minimum sight distance requirements are met. Trip Generation Based on trip generation fitted curve equations (higher than trip generation rates) from the 11th edition of the ITE Trip Generation Manual for Single Family Detached Homes (ITE Land Use Code 210) and General Office (ITE Land Use Code 710),the site is anticipated to generate 63 AM peak hour driveway trips and 69 PM peak hour driveway trips. As noted above, the trip generation was calculated for 18 dwelling units since 5 of the units are proposed outside of the gated area and not access North Carroll Avenue. A breakdown of the trip generation is provided in Table 1. No internal capture was assumed. Table 1: Trip Generation Analysis Trip Distribution and Assignment It is anticipated that the site traffic will be distributed to North Carrol Avenue and Southlake Boulevard accordingly: 30% to/from the west on Southlake Boulevard, 25% to/from the east on Southlake Boulevard, 30% to/from the north on North Carrol Avenue, and 15% to/from the south on North Carroll Avenue. In Out Total In Out Total Single-Family Detached Housing 210 18 Dwelling Units 208 4 12 16 12 8 20 General Office 710 23,000 SF 323 42 5 47 8 41 49 531 46 17 63 20 49 69TOTAL SITE TRAFFIC Daily AM Peak Hour PM Peak HourLand Use Description ITE Code Intensity / Units Page 3 Exhibit 3 (attached) provides the anticipated trip distribution at the two (2) project driveways and one (1) study intersection.Exhibit 4 (attached) provides the anticipated trip assignment at the driveways. Exhibit 5 (attached) provides the anticipated total traffic volumes at the driveways, including both current traffic along North Carroll Avenue (based on the weekday PM peak hour count at Nort Carroll Avenue & Main Street) and the proposed site traffic. The traffic volumes in Exhibit 5 account for the median modifications at Main Street. Based on the trip assignment values, the increase in traffic along North Carroll Avenue as a result of this proposed developments equates to less than a 2.0% increase between Southlake Boulevard and the site and less than 1% north of the site. DRIVEWAY CAPACITY ANALYSIS A capacity analysis was performed for the project driveways along North Carroll Avenue. Capacity analysis results are listed in terms vehicle delay and level of service (LOS). LOS is a qualitative term describing operating conditions (vehicle delay) a driver will experience while traveling on a specific street or highway during a specific time interval. It ranges from A (very little delay) to F (longer delays and congestion). TxDOT considers LOS D or better to be the target LOS for design and evaluation purposes. Average total delay ranges of each operational state for intersections, based on the Highway Capacity Manual (HCM) 6th Edition, are presented in Table 2. Table 2: Level of Service Definitions Level of Service Signalized Intersection Average Total Delay (sec/veh) Unsignalized Intersection Average Total Delay (sec/veh) A ≤10 <10 B >10 and ≤20 >10 and <15 C >20 and ≤35 >15 and <25 D >35 and ≤55 >25 and <35 E >55 and ≤80 >35 and <50 F >80 >50 The capacity analysis was performed using Synchro, which is an intersection analysis software based on the Highway Capacity Manual (HCM). The traffic volumes used for the analysis are the combination of the PM peak hour volumes provided collected in February 2024 and the site traffic volumes from Exhibit 2. As previously discussed, a northbound left-turn lane is proposed at the northern site driveway. This analysis accounts for the redistribution of existing WB left-turning traffic from Main Street that would make a WB right-turn movement and NB U-Turn movement at the proposed NB left-turn lane as a result of the City’s proposed median modifications along North Carroll Avenue at Main Street. Table 3 summarizes the intersection operation results for the three scenarios during the weekday AM and PM peak hours. The delay and LOS were reported for the stop-controlled eastbound movement at both driveways as well as the northbound left-turn movement at the northern driveways. Based on the analysis, all movements are anticipated to operate at LOS C or better during both the AM and PM peak hours. The Synchro 11TM output sheets for analyses are included as an Attachment. Page 4 Table 3: Level of Service Summary Due to the low number of right-turn volumes into the project driveways (+/- 7 vehicles during the AM peak hour and +/- 3 vehicles during the PM peak hour at each driveway), right-turn deceleration lanes are not recommended. The analysis further supports this as the southbound through movement is anticipated to operate at LOS A at both project driveways during the AM and PM peak hours. For the proposed NB left-turn lane, the anticipated 95th percentile queue during the PM peak hour is less than one vehicle (+/- 25 feet) based on the Synchro analysis. A conceptual layout of the turn lane is provided as an Attachment. The layout assumes a 75-foot taper and 75-feet of storage. If the City desires to have a longer taper length, the design could be modified to show a 100-foot taper and 50- feet of storage. CONCLUSION AND RECOMMENDATIONS A traffic study was performed for a residential and office development located on the west side of North Carroll Avenue, north of Southlake Boulevard, in the City of Southlake, Texas. The following conclusions can be made from the analysis: · The development is anticipated to include 23 single-family dwelling units and 23,000 square feet of general office space. Of the 23 residential units, 5 of them are proposed outside of the gated neighborhood and built along Cross Lane. The development represents less than a 3.0% increase in overall traffic volumes along North Carroll Avenue. · The development is anticipated to have two driveways accessing North Carroll Avenue; the northern driveway is anticipated to provide ingress and egress movements (left-turn egress prohibited) and the southern driveway is anticipated to provide ingress and egress movements (right-in and right-out only). The 5 residential units outside of the gated neighborhood will be access via Cross Lane. · In order to provide ingress from the south, which is anticipated to comprise of 70% of the total entering site traffic, a northbound left-turn lane is proposed at the northern site driveway. The left-turn lane would be designed similar to the existing southbound left-turn lane at Main Street, which has a similar width median. The southbound queues at the intersection of Southlake Boulevard & North Carroll Avenue are not anticipated to impact the proposed northbound left- turn lane operations. ·All traffic movements at the driveway connections are anticipated to operate at LOS C or better for during the PM peak hour. The northbound left-turn movement from the proposed left-turn lane is anticipated to operate at LOS C with less than one vehicle queue during both the PM peak hour. Delay (sec/veh)LOS EBR 12.0 B NBL / NBU 16.2 C North Carroll Avenue & Southern Driveway EBR 12.5 B North Carroll Avenue & Northern Driveway Intersection Movement PM Peak Hour Page 5 EXHIBITS LEGEND: = Study Intersections = Site Boundary EXHIBIT 1 VICINITY MAP WILLOWTREE GARDENS / THE OVERLOOK Drive 1 Drive 2 East SouthlakeBoulevard 861 872 861 872 137 812 49 49 735 112 LEGEND: X (Y) X = AM Peak Hour Turning Movements Y = PM Peak Hour Turning Movements Volumes may not sum from point to point due to rounding and presence of smaller driveways not included in analysis. EXHIBIT 2 EXISTING (2024) TRAFFIC VOLUMES N NOT TO SCALE WILLOWTREE GARDENS / THE OVERLOOK E SOUTHLAKE BLVD NCARROLLAVESITE MAIN STREET 15%15% (50%) 70%(30%) 15% (50%) (50%) 70% (30%) (70%) (30%) 70% 25% (30%) (15%) (25%) 30% 15% LEGEND: X (Y) X = AM Peak Hour Turning Movements Y = PM Peak Hour Turning Movements Volumes may not sum from point to point due to rounding and presence of smaller driveways not included in analysis. EXHIBIT 3 TRIP DISTRIBUTION N NOT TO SCALE WILLOWTREE GARDENS / THE OVERLOOK E SOUTHLAKE BLVD SITE NCARROLLAVE30%25% 15% 30% MAIN STREET 7 7 (3)(3) 9 (25) 32 5 (14)(15) 7 9 (3)(25) 37 (29) 9 (25) 12 0 5 (34)(0)(15) 32 0 (14)(0) LEGEND: X (Y) X = AM Peak Hour Turning Movements Y = PM Peak Hour Turning Movements Volumes may not sum from point to point due to rounding and presence of smaller driveways not included in analysis. EXHIBIT 4 TRIP ASSIGNMENT N NOT TO SCALE WILLOWTREE GARDENS / THE OVERLOOK E SOUTHLAKE BLVD NCARROLLAVESITE AM: 19 veh PM: 21 veh MAIN STREET AM: 44 veh PM: 48 veh 3 864 25 49 13 887 3 935 950 25 895 49 15 186 749 112 LEGEND: X (Y) X = AM Peak Hour Turning Movements Y = PM Peak Hour Turning Movements Volumes may not sum from point to point due to rounding and presence of smaller driveways not included in analysis. EXHIBIT 5 TOTAL TRAFFIC N NOT TO SCALE WILLOWTREE GARDENS / THE OVERLOOK E SOUTHLAKE BLVD NCARROLLAVESITE MAIN STREET 4:00 PM 4:15 PM 4:30 PM 4:45 PM PHF 186 214 210 202 0.948598 PHF 4:45 PM 4:30 PM 4:15 PM 4:00 PM 8 15 16 10 0.765625 0.962042 188 182 191 174 0.777778 25 36 23 28 4:00 PM 10 25 4:15 PM 14 31 4:30 PM 12 33 4:45 PM 13 48 PHF 0.875 0.713542 Page 6 CONCEPTUAL SITE PLAN Page 7 LEFT-TURN LANE CONCEPTUAL LAYOUT Relocate exisitng monument sign to north end of median. Maintain 16-foot median. Include a 2-foot median nose to prevent prohibited turning movements. Construct a median opening and provide a 4-foot median nose. Turn lane width +/- 10.5 feet. Construct a hooded left-turn lane to serve entry from the south into the development at this proposed driveway connection. 75 Feet of taper 75 Feet full width lane PROPOSED NORTHBOUND LEFT-TURN LANE NORTH CARROLL AVENUE SOUTHLAKE, TEXAS Proposed Right-In / Right-out Driveway Connection North Carroll Avenue Existing southbound left-turn lane to Main Street not impacted. The Container Store The Overlook / Willowtree Gardens Propsoed Development Page 8 SYNCHRO REPORTS HCM 6th TWSC Build-Out PM Peak Hour 1: N Carroll Ave. & Northern Driveway Synchro 11 Report Intersection Int Delay, s/veh 0.7 Movement EBL EBR NBU NBL NBT SBT SBR Lane Configurations Traffic Vol, veh/h 0 25 49 13 887 864 3 Future Vol, veh/h 0 25 49 13 887 864 3 Conflicting Peds, #/hr 0 0 0 0 0 0 0 Sign Control Stop Stop Free Free Free Free Free RT Channelized - None -- None - None Storage Length -0 - 100 --- Veh in Median Storage, # 0 ---0 0 - Grade, %0 ---0 0 - Peak Hour Factor 92 92 92 92 92 92 92 Heavy Vehicles, %2 2 2 2 2 2 2 Mvmt Flow 0 27 53 14 964 939 3 Major/Minor Minor2 Major1 Major2 Conflicting Flow All - 471 942 942 0 -0 Stage 1 ------- Stage 2 ------- Critical Hdwy - 6.94 6.44 4.14 --- Critical Hdwy Stg 1 ------- Critical Hdwy Stg 2 ------- Follow-up Hdwy - 3.32 2.52 2.22 --- Pot Cap-1 Maneuver 0 539 362 724 --- Stage 1 0 ------ Stage 2 0 ------ Platoon blocked, %--- Mov Cap-1 Maneuver - 539 388 388 --- Mov Cap-2 Maneuver ------- Stage 1 ------- Stage 2 ------- Approach EB NB SB HCM Control Delay, s 12 1.1 0 HCM LOS B Minor Lane/Major Mvmt NBL NBTEBLn1 SBT SBR Capacity (veh/h)388 - 539 -- HCM Lane V/C Ratio 0.174 - 0.05 -- HCM Control Delay (s)16.2 - 12 -- HCM Lane LOS C -B -- HCM 95th %tile Q(veh)0.6 - 0.2 -- HCM 6th TWSC Build-Out PM Peak Hour 2: N Carroll Ave. & Southern Driveway Synchro 11 Report Intersection Int Delay, s/veh 0.2 Movement EBL EBR NBL NBT SBT SBR Lane Configurations Traffic Vol, veh/h 0 25 0 950 935 3 Future Vol, veh/h 0 25 0 950 935 3 Conflicting Peds, #/hr 0 0 0 0 0 0 Sign Control Stop Stop Free Free Free Free RT Channelized - None - None - None Storage Length -0 ---- Veh in Median Storage, # 0 --0 0 - Grade, %0 --0 0 - Peak Hour Factor 92 92 92 92 92 92 Heavy Vehicles, %2 2 2 2 2 2 Mvmt Flow 0 27 0 1033 1016 3 Major/Minor Minor2 Major1 Major2 Conflicting Flow All - 510 -0 -0 Stage 1 ------ Stage 2 ------ Critical Hdwy - 6.94 ---- Critical Hdwy Stg 1 ------ Critical Hdwy Stg 2 ------ Follow-up Hdwy - 3.32 ---- Pot Cap-1 Maneuver 0 509 0 --- Stage 1 0 -0 --- Stage 2 0 -0 --- Platoon blocked, %--- Mov Cap-1 Maneuver - 509 ---- Mov Cap-2 Maneuver ------ Stage 1 ------ Stage 2 ------ Approach EB NB SB HCM Control Delay, s 12.5 0 0 HCM LOS B Minor Lane/Major Mvmt NBTEBLn1 SBT SBR Capacity (veh/h)- 509 -- HCM Lane V/C Ratio - 0.053 -- HCM Control Delay (s)- 12.5 -- HCM Lane LOS -B -- HCM 95th %tile Q(veh)- 0.2 -- Page 9 PHOTOLOG