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Item 6A Queuing and Signal Warrant Study1201 North Bowser Road Richardson, Texas 75081-2275 Technical Memorandum TO: Chris Lott FROM: Scott Booth, PE, PTOE DATE: October 23, 2018 RE : Queuing and Signal Warrant Study – Southlake Mixed-Use Office Addition Introduction Halff Associates, Inc. (Halff) was retained by North Carroll 114 Properties, LLC (Client) to prepare a Queuing and Signal Warrant Study supporting the proposed expansion of the mixed-use office located in the northwest quadrant of Carroll Avenue and Lakewood Drive in Southlake, Texas. An aerial image of the location and study intersection is shown in Figure 1 below. Figure 1 - Aerial View of Site and Study Intersection The proposed expansion increases the single-story office building size by 5,150 square feet, to a total of 11,750 square feet leasable area. There is a 450 square foot entry that brings the total building size to 12,200 square feet. With the proposed expansion, the existing driveway (currently located on Carroll Avenue just north of Lakewood Drive) is proposed to be relocated to Lakewood Drive. A copy of the proposed site plan with the proposed driveway relocation is attached. 10/23 /2018 North Carroll 114 Properties, LLC Queuing and Signal Warrant Study - 2 - The City of Southlake has requested that a queuing study for the eastbound approach of the Lakewood Drive and Carroll Avenue intersection be performed to determine the potential impact of the proposed change in access. In addition, the City requested that a Signal Warrant Study at the intersection be conducted to determine if future signalization is warranted. Data Collection Turning movement counts were collected at the study intersection and driveway during the weekday AM peak (7:00 to 9:00) and PM peak (4:00 to 6:00) hours. Based on the data collected, it was determined that 7:15 to 8:15 is the morning peak hour and 4:15 to 5:15 is the afternoon peak hour. In addition to the peak hour data, 24-hour approach counts were collected at the intersection of Lakewood Drive and Carroll Avenue. Copies of the traffic data are attached. Trip Generation and Distribution Using the collected traffic data, the peak hour trip generation for the existing office for the morning and the afternoon were determined. Based on that data, the office currently generates nine (9) trips (8 in, 1 out) in the AM peak and 24 trips (7 in, 17 out) in the PM peak. Using the proposed increase in the size of the office, a 78 percent increase, a straight-line projection for expected trips was calculated. With the proposed 11,750 square foot office the projected trips for the site would consist of 16 trips (14 in, 2 out) in AM peak and 42 trips (12 in, 30 out) in the PM peak. Figure 2 below shows the existing turning movement volumes at the study intersection and driveway. Figure 2 – Existing Volumes AM Peak 100 PM Peak (100) North Carroll 114 Properties, LLC Queuing and Signal Warrant Study - 3 - Trips related to the site were then redistributed based on the proposed relocation of the site driveway to Lakewood Drive. Figure 3 below shows the existing turning movement volumes at the study intersection, but with the site driveway relocated to Lakewood Drive and the trips related to the site adjusted to reflect the change. Figure 3 – Volumes with Relocated Site Driveway The next figure, Figure 4, shows the proposed driveway configuration, but includes the increase in site related trips due to the new office space. This figure represents the projected volumes at the intersection of Carroll Avenue and Lakewood Drive with the proposed office addition being constructed. Figure 4 – Volumes with Relocated Site Driveway AM Peak 100 PM Peak (100) AM Peak 100 PM Peak (100) North Carroll 114 Properties, LLC Queuing and Signal Warrant Study - 4 - Queuing Study Using the turning movement volumes from Figure 2 and Figure 4, queues for the left turn movement on the eastbound approach of Lakewood Drive were compared for the existing condition and the future condition (with relocated driveway and additional office space). Table 1 below summarizes the eastbound queues for the given scenarios. Table 1 – Queuing Analysis Summary Scenario 95 th Percentile Queue (Max Queue) Vehicles Length (ft) AM Peak - Existing < 1.0 < 20 PM Peak - Existing < 1.0 < 20 AM Peak - Proposed < 1.0 < 20 PM Peak - Proposed 1.3 32 In the table above, the queue shown is the 95 th percentile queue or max queue. Stated another way; 95 percent of the time, the queue at the eastbound approach will not be any longer than that listed in the table and most likely will be shorter. The queues for the right-turn movement from Lakewood Drive are negligible in length during both the AM and PM peak hour, even with the addition of traffic related to the site. Signal Warrant Study A signal warrant study consists of the examination of nine warrants, which are: • Warrant 1: Eight-Hour Vehicular Volume • Warrant 2: Four-Hour Vehicular Volume • Warrant 3: Peak Hour • Warrant 4: Pedestrian Volume • Warrant 5: School Crossing • Warrant 6: Coordinated Signal System • Warrant 7: Crash Experience • Warrant 8: Roadway Network • Warrant 9: Intersection Near a Grade Crossing According to the Texas Manual of Uniform Traffic Control Devices (TxMUTCD), a traffic control signal should not be installed unless one of the above warrants is met, but meeting a traffic signal warrant does not automatically justify the need for a traffic signal. For warrants based on traffic volume thresholds, the threshold may be reduced under certain conditions such as an isolated signal with a population less than 10,000 individuals, or if the posted (or 85 th percentile) speed on the major road is greater than 40 miles per hour. Since the posted speed limit on Carroll Avenue does not exceed 40 miles per hour, the reduced thresholds are not applicable to the study intersection. North Carroll 114 Properties, LLC Queuing and Signal Warrant Study - 5 - Based on a review of the above warrants and the given conditions at the study intersection, it was determined that Warrants 4, 5, 6, 7 and 9 were not applicable. This leaves warrants 1, 2, 3, and 8, which are based on vehicle volumes at the study intersection. Table 2 below summarizes the approach volumes for the twelve highest hours of the day. Table 2 – Carroll Avenue at Lakewood Drive Approach Volumes Hour/Time Approaches NB EB SB WB 1 7:00 AM 739 27 726 - 2 8:00 AM 739 31 820 - 3 9:00 AM 589 19 732 - 4 10:00 AM 586 25 720 - 5 11:00 AM 716 24 863 - 6 12:00 PM 887 36 1032 - 7 1:00 PM 990 37 836 - 8 2:00 PM 920 35 808 - 9 3:00 PM 880 29 951 - 10 4:00 PM 839 36 984 - 11 5:00 PM 828 42 1018 - 12 6:00 PM 845 30 857 - Warrant 1 – Eight-Hour Vehicle Volume Warrant 1 is broken down into two sub categories, condition A (minimum vehicular volume) and condition B (interruption of continuous traffic). The standard indicates that the warrant is met if either condition A or B is met for any eight hours on an average day. Condition A From Table 4C-1 in the TxMUTCD, with two or more lanes on the major approach and two or more lanes on the minor approach, the threshold of volumes for Condition A is as follows: • Major: 600 vehicles per hour (combined total of both approaches) • Minor: 200 vehicles per hour (higher volume approach) Based on the data shown in Table 2, these thresholds are not exceeded during any of the one- hour periods at the study intersection. Condition A is not met. Condition B From Table 4C-1 in the TxMUTCD, with two or more lanes on the major approach and two or more lanes on the minor approach, the threshold of volumes for Condition B is as follows: • Major: 900 vehicles per hour (combined total of both approaches) • Minor: 100 vehicles per hour (higher volume approach) North Carroll 114 Properties, LLC Queuing and Signal Warrant Study - 6 - Based on the traffic data in Table 2, these thresholds are not exceeded during any one-hour period at the study intersection. Condition B is not met. The TxMUTCD allows for a combination of Condition A and B with a reduced threshold of 80 percent. For Condition A the thresholds would be 480 vehicles per hour (both directions combined) on the major street and 160 per hour at the highest minor street approach. The thresholds for Condition B would be 720 vehicles per hour on the major street and 80 vehicles per hour on the minor street approach. Based on these criteria, not one of the one-hour periods meet or exceed the threshold for Condition A nor Condition B. Neither Condition A or B are met, therefore Warrant 1 is not met at this time. Warrant 2 – Four-Hour Vehicle Volume The standard for the four-hour vehicle volume warrant is met if the plotted points representing the vehicles per hour on the major street (total of both approaches) and the vehicles per hour of the higher volume minor street approach all fall above the applicable curve in Figure 5 (Figure 4C-1 from the TxMUTCD) shown below. Figure 5 – Plotted Four-Hour Volumes Based on the data shown in the graph above, none of the plotted points are above the threshold curve for “two or more lanes and two or more lanes;” therefore, Warrant 2 is not met. North Carroll 114 Properties, LLC Queuing and Signal Warrant Study - 7 - Warrant 3 – Peak Hour From the TxMUTCD: The Peak Hour signal warrant is intended for use at a location where traffic conditions are such that for a minimum of 1 hour of an average day, the minor-street traffic suffers undue delay when entering or crossing the major street, The need for a traffic control signal shall be considered if an engineering study finds that the criteria in either of the following two categories are met: A. The peak hour warrant is met if all three of the following conditions exist for the same one hour (any four consecutive 15-minute periods) of an average day: 1. The total stopped time delay experienced by the traffic on one minor-street approach (one direction only) controlled by a STOP sign equals or exceeds: 4 vehicle-hours for a one- lane approach; or 5 vehicle-hours for a two-lane approach, and 2. The volume on the same minor-street approach (one direction only) equals or exceeds 100 vehicles per hour for one moving lane of traffic or 150 vehicles per hour for two moving lanes, and 3. The total entering volume serviced during the hour equals or exceeds 650 vehicles per hour for intersections with three approaches or 800 vehicles per hour for intersections with four or more approaches. B. The plotted point representing the vehicles per hour on the major street (total of both approaches) and the corresponding vehicles per hour on the higher-volume minor-street approach (one direction only) for 1 hour (any four consecutive 15-minute periods) of an average day falls above the applicable curve in Figure 4C-3 for the existing combination of approach lanes. In examining the requirements of Category A, the highest approach volume on the minor street (Lakewood Drive) was 42 vehicles per hour. This does not exceed the requirement in A2 of 150 vehicles per hour. Therefore, the conditions of Category A are not met and Warrant 3 is not met. Warrant 8 – Roadway Network This warrant examines the need for a signal as a way to improve organization of traffic flow on the roadway network. This warrant is met if the study intersection meets the requirement of having an entering volume of at least 1,000 vehicles per hour during the peak hour and has 5-year projected volumes that meet one or more of Warrants 1, 2 or 3. While the study intersection does have over 1,000 vehicles entering during the peak hour, it is not projected to meet any of Warrants 1, 2 or 3 in the next 5 years. For this to occur, the traffic volumes on Lakewood Drive would need to triple (25 percent annual growth rate) to even come close to meeting the requirements for Warrant 3 (Peak-Hour Warrant). North Carroll 114 Properties, LLC Queuing and Signal Warrant Study - 8 - Summary Based on the analyses presented in the memorandum above, the relocation of the development driveway to Lakewood Drive does not appear to significantly impact the queues on the eastbound approach (Lakewood Drive) at the intersection of Carroll Avenue and Lakewood Drive. It is noted that there is a small increase in the 95 th percentile queue in the PM peak hour due to the additional projected trips related to the proposed increase in office space. But, the overall max queue (slightly over one vehicle in length) remains well within normal parameters for a two-way stop-controlled intersection on a major thoroughfare. Based on a review of the Signal Warrants as contained in the TMUTCD, the intersection of Carroll Avenue and Lakewood Drive does not meet any of the signal warrants, nor is it projected to meet any Warrant within the next five (5) years.