Technical Memrandum T: Mr. Eduard Garcia, PSW Real Estate, LLC Frm: Christy Lambeth, P.E., PTOE Lambeth Engineering Assciates, PLLC, F-19508 Date: May 29, 2018 Re: Traffic Assessment fr Prpsed Single-Family Develpment n White Rck Trail in Dallas, Texas (Dallas Case #Z178-278/SM, LEAP #18105) Intrductin May 29, 2018 The services f Lambeth Engineering Assciates, PLLC (LEAP) have been retained t cnduct a traffic assessment fr the prpsed single-family residential develpment in the suthwest crner f the Walnut Hill Lane/White Rck Trail intersectin in Dallas, Texas. The currently vacant prperty frmerly had ffice buildings that were demlished. The prpsed develpment will have 38 single-family lts with vehicular access n White Rck Trail. The prperty is currently zned NO(A) Neighbrhd Office District with deed restrictins; a residential planned develpment is being prpsed. The purpse f this study is t prject the anticipated traffic that will be generated by the prpsed develpment and make bservatins f current traffic flw near the site. The develpment is nt expected t have significant impact t the radway netwrk (as will be shwn in this mem) and apprval is recmmended. Prjected Traffic Vlumes The Institute f Traffic Engineers (ITE) Trip Generatin Manual, 10 th Editin, is a cllectin f traffic data fr specified uses. The manual prvides data cllected ver several years fr a wide variety f uses fr the purpse f calculating prjected traffic vlumes that a prpsed develpment will generate. The traffic vlumes are summarized in terms f trips t and frm the develpment. Fr example, a vehicle leaving hme t g t wrk and then returning hme will generate tw trips ne utbund trip during the mrning and ne inbund trip during the afternn. The prjected traffic fr 38 single-family lts, including the highest peak hurs, is summarized in Table 1. There will be additinal vehicles leaving/entering the site during the mrning/afternn perids, hwever this activity is expected t ccur utside f the peak hurs. As shwn, the peak travel perids t/frm the develpment include 24 vehicles leaving the site during the AM peak hur and 25 vehicles arriving during the PM peak hur. Table 1. Prjected Traffic Vlume Summary fr 38 Single Family Lts Ttal Inbund Outbund AM Peak Hur 32 8 24 Schl Afternn Peak Hur 31 18 13 PM Peak Hur 40 25 15 Weekday Ttal 427 213 213 Nte: This study des nt cnsider the site s prximity t the Lake Highlands DART statin, which may decrease the prjected vehicular traffic t/frm the site. 8637 CR 148, Kaufman, TX 75142 972.989.3256 christy@lambethengineering.cm
Existing Queue n White Rck Trail In rder t assess the ability f vehicles t easily leave the site during peak hurs, the current queue was bserved with resepct t the prpsed access radway lcatin near the center f the prperty. This bservatin nted that apprximately 10-12 nrthbund vehicles can queue befre blcking the prpsed access rad. The nrthbund queue n White Rck Trail at Walnut Hill Lane was evaluated during the AM peak hur, schl afternn peak hur, and during the PM peak hur n Friday, May 25, 2018. Observatins are described belw and detailed ntes are attached. The White Rck Trail nrthbund/suthbund mvements perate during the same phase/at the same time and there are n prtected left-turn mvements (nly permitted). Therefre, nrthbund left-turning vehicles must yield t ppsing suthbund thrugh/right-turning vehicles. AM Peak Hur: White Rck Trail had apprximatley 44 secnds f green time and Walnut Hill Lane abut 115 secnds f green time. The queue cmpletely dispersed during each cycle at each apprach. The queue exceeded ten (10) vehicles during fur cycles. Hwever, the peak queue lasted nly abut 5-15 secnds per cycle and the queue cmpletely dispersed during each cycle. The suthbund traffic n White Rck Trail was minimal; therefre, nrthbund thrugh and left-turning vehicles were nearly free-flwing thrugh the intersectin. Traffic flwed smthly frm White Rck Trail during the AM peak hur. The majrity f the prpsed site traffic is expected t turn left tward Walnut Hill Lane rather than travel thrugh the neighbrhd. There were plenty f gaps in traffic fr left-turning vehciles t leave the prpsed access during the AM peak hur. Schl PM Peak Hur: White Rck Trail had apprximatley 33 secnds f green time and Walnut Hill Lane abut 125 secnds f green time. The suthbund traffic n White Rck Trail was light; therefre, nrthbund thrugh and left-turning vehicles did nt have difficulty prceeding thrugh the intersectin. The nrthbund queue did nt cmpletely disperse during each cycle, appearing t be attributed t the shrter green time fr White Rck Trail cmpared t the mrning. The queue exceeded ten (10) vehicles during fur cycles: lasting abut 5-35 secnds fr three f the cycles and abut a minute fr ne cycle. If the queue were t be able t cmpletely disperse during each cycle, the queue wuld be shrter and wuld lessen the times the queue exceeds ten (10) vehicles. The queues created n Walnut Hill Lane during its red time cleared during each cycle. Since the queue lessened between the few cycles when there were mre than ten (10) queued vehicles, this prvided plenty f gaps fr left-turning vehicles t leave the prpsed driveway during the schl afternn peak hur. Recmmendatin: Extend green time n White Rck Trail during schl PM perid t allw the nrthbund queue t fully disperse during each cycle. White Rck Trail Traffic Assessment fr Prpsed Single-Family Develpment Page 2
PM Peak Hur: Sight Distance White Rck Trail had apprximatley 33 secnds f green time and Walnut Hill Lane abut 125 secnds f green time. During the time bserved, the queue exceeded ten (10) vehciles during seven cycles. The nrthbund queue did nt cmpletely disperse during each cycle due t nrtbund vehicles yielding right-f-way t suthbund vehicles and shrter green time. The suthbund traffic n White Rck Trail was nt very heavy, but was enugh t cause delay fr nrthbund vehicles during several PM cycles with nrthbund/ suthbund vehicles yielding t each ther. Twice it was bserved that nly ne r tw f the nrthbund, left-turning vehicles were able t clear the intersectin during a cycle due t yielding t suthbund vehicles and sme nrthbund vehicles had t wait thrugh three cycles befre they culd prceed thrugh the intersectin. It is imprtant t nte that, while this did nt ccur ften, it did create a significant delay n White Rck Trail when it ccurred. As an alternative t waiting thrugh the cycles, vehicles leaving the prpsed site can turn right during the rare peak times when the queue is nt dispersing near the prpsed access radway. Recmmendatin: Extend green time n White Rck Trail during the PM peak perids t allw the nrthbund queue t fully disperse during each cycle. After green time is extended, reasses the nrthbund queue n White Rck Trail t determine if the queue is mre quickly being dipsersesed r if prtected left-turns n White Rck Trail shuld be evalauted t facilitate the nrthbund/suthbund traffic yielding t ne anther. Adequate sight distance must be prvided at intersectins fr mtrists t turn safely. The City f Dallas s Off-Street Parking and Driveways Handbk prvides required and desireable sight distances based upn speed. A cursry sight distance evaluatin was made during the field visit t ensure that the lcatin f the prpsed access satisfies the City s requirements. As shwn in Table 2, sight distance is satisfied. Pictures f the prpsed access lcatin are shwn in Figure 1 and Figure 2.. Table 2. Sight Distance fr Prpsed Access Rad n White Rck Trail Left Sight Distance Right Sight Distance Study Drieway Design Speed Min Req'd Desireable Prvided Min Req'd Desireable Prvided Prpsed Access Drive at White Rck Trail 30 MPH 145' 315' >~335' 200 315 >~560' White Rck Trail Traffic Assessment fr Prpsed Single-Family Develpment Page 3
Figure 1. Left Sight Distance Figure 2. Right Sight Distance Summary The prpsed 38-lt, single-family develpment will nt have a significant impact n the surrunding radway netwrk. LEAP understands that there are currently traffic delays at the White Rck Trail/ Walnut Hill Lane intersectin during certain afternn cycles and has prvided recmmendatins that may lessen these delays. Hwever, the prject will nt have a significant impact even withut the recmmended signal imprvements since it is prjected t generate nly 15 nrthbund vehicles leaving the site during the PM peak hur which equates t abut ne vehicle every fur minutes. It is imprtant t cnsider the fact that the majrity f the traffic fr a single-family develpment is entering the develpment during the PM peak hur, with a smaller percentage leaving during this perid. The site is currently zned fr ffice-uses. If an ffice were develped at this lcatin, the majrity f traffic wuld be leaving the site during the afternn. And, if an ffice f the same size as the ne that was demlished were built, the amunt f traffic leaving the site during the afternn heading tward Walnut Hill Lane is prjected t be three times that f the prpsed single-family develpment. A medical ffice use is als permitted n the site with the current zning and wuld have seven times the traffic leaving the site during the PM peak hur cmpared t the prpsed single-family develpment. The lcatin f the new access radway prvides adequate sight distance and there are sufficient gaps in the traffic fr mtrists t leave the site during the mrning and schl afternn peak perids. When suthbund White Rck Trail traffic is light, there are sufficient gaps during the PM peak hur as well. It is recmmended that the City reevaluate and extend the green time n White Rck Trail at the Walnut Hill Lane intersectin t help lessen the existing nrthbund queue n White Rck Trail during the PM peak perid. Lambeth Engineering Assciates, PLLC, recmmends apprval f the requested zning change t allw develpment f the 38 single-family residential lts. The prpsed residential develpment will have the least impact t the White Rck Trail/Walnut Hill Lane intersectin cmpared t ther uses (such as an ffice, medical ffice r financial institutin) fr which the prperty is currently zned. END White Rck Trail Traffic Assessment fr Prpsed Single-Family Develpment Page 4
Appendix White Rck Trail Traffic Assessment fr Prpsed Single-Family Develpment
Queue Observatins Date: Lcatin: Friday, May 25, 2018 White Rck Trail at Walnut Hill Lane, Dallas, TX Descriptin: Observed by: Prject: Nrthbund Queue n White Rck Trail at Walnut Hill Ln Sunny and clear, White Rck Elementary Schl in Sessin Christy Lambeth Traffic Assessment fr Prpsed Single Family Develpment n White Rck Trail in Dallas, TX LEAP# 18103 Friday, May 25, 2018 Time Nrthbund Queue AM: All queued vehicles cleared intersectin during each cycle during the AM bservatins. 7:41 AM 6 AM Peak: All 14 + 2 extra vehicles prceeded thrugh intersectin 16 ttal cleared 7:42 AM 9 7:45 AM 8 7:47 AM 11 7:49 AM 11 7:51 AM 14 7:53 AM 11 7:55 AM 3 7:57 AM 7 7:59 AM 2 8:01 AM 8 8:03 AM 2 8:21 AM 2 Schl Afternn: White Rck Trail green time abut 10 secnds less than AM 2:53 PM 6 Queue did nt cmpletley clear intersectin each cycle during schl PM, sme vehicles 3:00 PM 6 waited tw cycles t clear intersectin. Lnger green time wuld likely allw all t clear. 3:02 PM 9 3:05 PM 7 3:07 PM 15 3 vehciles did nt clear intersectin 3:10 PM 15 6 vehicles did nt clear intersectin 3:12 PM 12 3 vehciles did nt clear intersectin 3:15 PM 9 3:18 PM 16 4 vehciles did nt clear intersectin Schl PM Peak: 16 vehicles 3:20 PM 9 3:23 PM 8 3:26 PM 3 3:28 PM 6 3:30 PM 7 PM: White Rck Trail green time abut 10 secnds less than AM 4:30 PM 14 8 vehicles did nt clear intersectin 4:32 PM 11 4:36 PM 12 11 vehicles did nt clear intersectin 4:36 Vehcile 1 cleared (1 vehcile cleared) 4:39 PM 15 7 vehicles did nt clear intersectin 4:36 Vehicles 2 9 cleared (8 vehicles cleared) 4:41 PM 12 4 vehicles did nt clear intersectin 4:36 vehciles 10 12+ cleared (8 vehicles cleared) 4:43 PM 10 2 vehicles did nt clear intersectin (8 vehciles cleared) 4:47 PM 3 4:49 PM 0 light queue frm 4:50 t 5:00 5:01 PM 2 5:04 PM 10 5 vehicles did nt clear intersectin 5:04 vehicles 1 5 cleared (5 vehciles cleared) 5:06 PM 9 7 vehicles did nt clear intersectin 5:04 Vehicles 6 7 cleared (2 vehciles cleared) (Christy had t leave site) 5:04 Vehicles 8 10 +cleared Printed n 05/29/2018 White Rck Trail LEAP #18103
Trip Generatin Summary ITE Land Use Quantity AM In Out PM In Out Weekday 210 Single Family 38 Lts 32 8 24 40 25 15 427 710 General Office 46,415 SF 70 60 10 55 9 46 504 720 Medical Office 46,415 SF 113 88 25 159 45 114 1,696 Calculated using ITE Trip Generatin Manual, 10th Editin Printed n 05/29/2018 White Rck Trail LEAP #18103