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Item 7C - Lee Engineering TIA Review #2 - 08-19-202171..E rcncinramnc August 19, 2021 Sandy Endy, P.E. Development Engineer City of Southlake 1400 Main Street, Suite 320 Southlake, Texas 76092 Re: Drive -Through Queue Study, NW Corner of Southlake & White Chapel — Review #2 Dear Ms. Endy: ARIZONA TEXAS NEW MEXICO OKLAHOMA Per your request, we have completed an updated review of new documents submitted for the proposed redevelopment on the northwest corner of the intersection of FM 1709 (Southlake Boulevard) and White Chapel Boulevard in Southlake, Texas. Lee Engineering previously reviewed the traffic study titled "Drive -Through Queue Analysis, NW Corner of Southlake & White Chapel, Southlake, Texas", which was prepared by Traffic Impact Group, LLC, and dated June 9, 2021. The previous version of the site plan received by LEE was dated June 28, 2021. This review includes the following documents: An updated site plan dated August 13, 2021 A City of Southlake TIA Threshold Worksheet dated August 13, 2021 A document titled "Southlake Coffee Responses" prepared by Traffic Impact Group, LLC Comments are numbered for ease of reference and the numbering does not imply any ranking. We have divided our comments into two categories — Informational Comments are those that require no action by the City or the applicant. Action Comments are those that require a response or action by the City or applicant. We offer the following comments on the submitted study. INFORMATIONAL COMMENTS (REQUIRE NO ACTION BY CITY OR APPLICANT) The previous traffic study indicated that the redeveloped site would include a new 4,600 square foot building, with a 2,500 square foot retail site and a 2,100 square foot restaurant with drive -through window. The study indicated that it was likely that the restaurant would be a coffee shop, although no tenants are planned at this time. • However, the updated site plan identifies a building size of 4,788 square feet. It is not clear whether the restaurant or retail portion of the building would be increased. 2. Aside from the proposed building size, the site plan appears to be unchanged from the previous submittal. 3. As part of the TIA threshold worksheet, a trip generation table was prepared for the overall retail site to determine how trip generation would change with the redevelopment of the existing gas station to the proposed coffee/retail building. 3030 LBJ Freeway, Suite 1660, Dallas, TX 75234 (972) 248-3006 office (972) 248-3855 fax I www.leeengineering.com Page 1 of 3 4. The comment response document indicates that pass -by percentage for fast-food restaurants (50%) is still a reasonable assumption for the percentage of vehicles entering the drive -through for the coffee shop. The comment response document did provide information to justify the use of a 60-second processing time for the drive -through. The document identifies recent data collection by Scooter's Coffee which showed an average order time 24 seconds and an average time at the pick-up window of 32 seconds. ACTION COMMENTS (REQUIRE RESPONSE OR ACTION BY CITY OR APPLICANT) The trip generation table provided with the TIA threshold worksheet identifies a coffee shop with 2,350 square feet and a retail portion of the building with 2,322 square feet. If the coffee shop is larger, this will result in a slightly higher drive -through demand than shown in the previous traffic study. Additionally, as stated above, the site plan shows a larger building size at this time. Please provide a final study that matches the site plan sizes. LEE has been unable to verify the trip generation results shown in the TIA threshold worksheet using the latest edition (101h) of ITE Trip Generation. We calculated different values for all land uses. It is also unclear what is being considered as the peak hour in the provided table, as the peak ingress volume for the gas station appears to be for the PM peak hour and the peak ingress volume for the coffee shop appears to be for the AM peak hour. Please confirm calculations and specify what design hour is being provided. 8. If the percentage of traffic accessing the site via the drive-thru is higherthan estimated in the queuing study, then the queue is likely to spill back far enough to conflict with traffic accessing the site from White Chapel. This would indicate the need for a longer throat depth at the southern White Chapel driveway, or a different queue configuration. Absent count data specific to the coffee shop showing of drive-thru or in-store traffic, the assumption based on ITE pass -by percentage may be the only information available. LEE still believes the percent of drive-thru traffic to be higher but doesn't not have a data source to recommend at this time. • As the percentage increase, the queue lengths predicted will increase. 9. An issue associated with the site is how the driveway ordinance gets applied in a situation like this where an existing driveway is being connected to an existing site. Ultimately any decision or recommended action relative to the application of the ordinance falls to the City. • The existing driveways do not appear to comply with the driveway ordinance due to spacing constraints and possibly throat depths. A variance was likely granted during the original development of the site though LEE is unaware of the official record at this time. • The City of Southlake Driveway Ordinance states that "existing driveways that are not in conformance with this ordinance shall be brought into compliance" if the existing driveway volume is projected to increase by 20% or more during the design hour or if substantial changes to the uses are likely to create traffic concerns. • The proposed changes to the overall site, namely the proposed connection between the central aisle of the grocery site and the existing driveway that will now have direct access from FM 1709, may also result in trips increasing 20% or more during the peak hour on this driveway. i. We disagree with the comment response that the driveway to the west that aligns with the face of the retail buildings on the overall site will remain the primary entry from FM 1709. Grocery traffic entering from FM 1709 will likely shift east to the more direct access point. LEE rine ra:nne Page 2 of 3 • Overall, for the entire development shown in the trip generation calculations, LEE estimates that entering volumes increases by approximately 18 percent during the AM peak hour and decrease by approximately 3 percent during the PM peak hour with the redevelopment. This overall increase will be concentrated at the two site drives nearest the proposed use. If the two driveways adjacent to the new coffee shop are considered to primarily serve just that portion of the overall site, then the volume for each driveway is predicted to increase by approximately 52 percent during the AM peak hour and decrease by approximately 28 percent during the PM peak hour. i. No existing counts were provided, and no site traffic figure showing the reassignment of traffic from the existing counts and the proposed development to the various site driveway was provided to allow a determination of whether the proposed traffic changes on this driveway exceed the 20% threshold. • If the ordinance provision to bring the driveways into compliance is applicable, a variance could continue to be granted regarding spacing and auxiliary lane requirements if the southeastern driveway to FM 1709 remains in place. Attempts to meet the spacing requirements would require closure of the driveway entirely. An auxiliary lane, while possibly warranted based on the City ordinance volume threshold cannot be reasonably constructed due to the topography of the site. iii. If the site plan connection between the coffee shop site and the main grocery aisle is eliminated, then the volume increase on the driveway would be limited to site traffic from the proposed coffee/retail development only versus site traffic plus additional traffic accessing the grocery store. Please contact Kristen Novak or me with further questions. Sincerely, RELEASED ELECTRONICALLY FOR REVIEW PURPOSES ONLY John Denholm III, PE, PTOE Lee Engineering TBPE Firm F-450 LEE rinenra:inc Page 3 of 3