MEMORANDUM: INTERIM CONCEPTS

Transcription

1 roject I 15/Tropicana Interchange Feaibility Study MEMORANDUM: INTERIM CONCETS INTRODUCTION During the initial project creening and throughout the development of project concept, alternative concept which could temporarily improve operation of I 15 and/or Tropicana interchange and the vicinity were creened from the potential ultimate alternative() election. Thi memo preent the interim concept to be conidered for immediate or near future implementation. The interim concept are proviional until ultimate improvement can be contructed. Until the I 15/Tropicana interchange i complete, implementation of interim concept could offer poitive benefit for the period between preent day and project completion. All interim concept conider that the roject NEON contruction will reconfigure I 15 Expre Lane and General urpoe (G) lane to conform to the Southern Nevada High Occupancy ehicle (HO) Study update configuration. ALTERNATIE CONCET IDENTIFICATION An initial concept memo wa provided to NDOT that decribed a number of improvement that could be conidered for implementation or further tudy. NDOT management requeted that the following concept be evaluated further for interim implementation. NB I 15 Lane Configuration: reented in the initial concept memo a Reconfigure I 15 Lane, two different interim NB lane configuration were identified for further evaluation. The two concept have been refined and are a follow. Interim Option 1 11 foot lane under Tropicana (4 G + 1 HO + 1 CD on ramp/auxiliary). A named, the configuration propoe to reduce the width of the lane on I 15 to 11 feet in order to not require immediate replacement of the Tropicana overpa tructure. Thi allow for the lane configuration propoed by roject NEON to fit under the bridge along with an auxiliary lane from the northbound CD entrance to Spring Mountain. The width of the lane could be widened back to 12 foot after paing under the Tropicana Bridge. Interim Option 2 12 foot lane under Tropicana (3 G + 1 HO + 1 CD on ramp/auxiliary). The configuration propoe to reduce the number of G lane on I 15 in advance of the northbound CD road entrance, uing 12 foot lane for all lane. The CD road entrance would be an auxiliary lane to Spring Mountain. SB CD Road Choice Lane Split at I 15/CC 215: Thi concept wa identified in the initial concept memo a the SB CD Choice Lane, and ha been further evaluated to determine the potential benefit of implementation. While thi option wa preented a a potential initial concept, the concept ha been further refined a an interim olution that will need to be expanded once Clark County improve CC 215 wetbound from the I 15 Interchange to Decatur. age 1 of 16

2 roject I 15/Tropicana Interchange Feaibility Study EALUATION/ANALYSIS METHODOLOGY The traffic operation analyi wa performed baed on the methodology decribed in Highway Capacity Manual (HCM 2010). HCS 2010 Facility module wa ued for the analyi of baic freeway, on and offramp (Merge/Diverge) and weaving egment. Microoft Excel preadheet/hand calculation were performed when HCS oftware did not provide adequate reult. The LOS wa ued a a performance meaure for evaluating the option. The following exhibit from HCM 2010 provide the criteria for determining the LOS. Analye are ued for comparative purpoe only and the LOS provided i not intended to reflect the actual LOS of I 15 or the CD road. Methodology pecific are noted further in the individual option dicuion. HCM 2010 EXHIBIT 11 6 HCM 2010 Exhibit LOS for Weaving Segment Denity (pc/mi/ln) LOS Weaving Segment on Freeway Weaving Segment Multilane Highway or C D Roadway A B >10 20 >12 24 C >20 28 >24 32 D >28 35 >32 36 E >35 >36 F Demand exceed capacity HCM 2010 Exhibit 13 2 LOS Criteria for Freeway Merge & Diverge Segment LOS Denity (pc/mi/ln) Comment A 10 Unretricted operation B >10 20 Merging and diverging maneuver noticeable to driver C >20 28 Influence area peed begin to decline D >28 35 Influence area turbulence become intruive E >35 Turbulence felt by virtually all driver F Demand exceed capacity Ramp and freeway queue form age 2 of 16

3 roject I 15/Tropicana Interchange Feaibility Study CONCET DISCUSSION NB I 15 Lane Configuration The roject NEON Deign Build roject will reconfigure the I 15 mainline lane, reulting in a lane configuration of 1 HO lane and 4 G lane from Silverado Ranch to the Spaghetti Bowl (US95/US93 and I 15 ytem to ytem interchange). Analyi ha hown that improvement to the I 15 operation in the vicinity of Tropicana i poible if the exiting northbound CD road entrance ramp i reconfigured. Currently, the exiting CD road entrance ramp to I 15 conit of a merge taper ramp entrance prior to the Tropicana bridge tructure. The intent of both NB I 15 lane configuration interim option i to provide an extenion of the northbound CD road a an auxiliary lane to Spring Mountain. Both option were evaluated uing HCS 2010 Facility Module which i baed on HCM methodology. The reult provide a comparative analyi of the roject NEON lane configuration with a merge taper entrance from the CD againt each of the propoed option. Traffic Analyi of the exiting condition (CD ramp entrance) wa evaluated with HCS for the interim configuration. The analyi conit of baic freeway, merge/diverge and weaving configuration. Figure 1 provide the NB I 15 traffic volume, lane and HCS reult that include peed, denity and LOS. FIGURE 1: NO BUILD ANALYSIS RESULTS 2020 olume AM (M) eak Aumption: 2020 No Build ha 1HO + 4 G lane Interim Option 1 11 foot lane NB under Tropicana Uing the pace offered by reducing I 15 lane width while alo reducing the exiting outide houlder and eliminating the 3 foot HO buffer, Interim Option 1 propoe ix 11 foot lane paing under the exiting bridge at Tropicana. The ditance between the median barrier and the eat bridge abutment i 73 feet. Thi pace allow the ix 11 foot lane, a 2 foot left houlder, and a 5 foot right houlder. The evaluation aumed that the HO lane would remain 12 foot wide, o elimination of the buffer i required to maintain more than a 2 foot outide houlder. Exhibit 1 i provided for reference and how a graphical depiction with all lane of 11 foot width and no HO buffer. age 3 of 16

4 roject I 15/Tropicana Interchange Feaibility Study The limit of the 11 foot lane would only need to extend to the taper ditance on either ide of the Tropicana Bridge. Exhibit 2 how the approximate limit of 11 foot lane width. Deign exception would be required for the reduced lane and houlder width. The CD Ramp entrance will extend a an auxiliary lane all the way to the point that the outide lane terminate into the Spring Mountain exit ramp. To alleviate a neceary 3 lane weave from the Tropicana entrance ramp to I 15, the exiting two lane entrance ramp i reduced to a ingle lane ramp that i an auxiliary lane to Flamingo. Tropicana to I 15 road uer will need to make a 1 lane ramp to freeway (RF) weave between Tropicana and Flamingo to avoid being trapped into exiting at Flamingo. The configuration wa teted with both a ingle lane and a two lane exit at Flamingo a illutrated in Figure 2 and 3. The ingle lane exit at Flamingo provided poor LOS in the weave area between the NB CD and the Tropicana entrance ramp compared to a two lane exit due to the road uer pre poitioning for the freeway to ramp (FR) weave. Traffic analyi for Interim Option 1 wa evaluated uing HCS. Figure 2 provide the NB I 15 traffic volume, lane and HCS reult that include peed, denity and LOS. Figure 3 provide the ame data, but with a ingle lane exit ramp to Flamingo. Schematic of 1 lane off ramp veru 2 lane off ramp at Flamingo 2 lane exit 1 lane exit age 4 of 16

5 roject I 15/Tropicana Interchange Feaibility Study EXHIBIT 1: ROOSED TROICANA CROSS SECTION age 5 of 16

6 ALIBABA LN. DEAN MARTIN DR. R/W TROICANA AE. EXIST. BRIDGE COLUMNS DEAN MARTIN DR. R/W 1- HO 5-11' S RENO AE. BUFFER OTIONAL R/W FRANK SINATRA DR. R/W EXIST. BRIDGE COLUMNS 2770' INTERSTATE 15 INTERIM OTION 1 - LEGEND - STATE OF NEADA DEARTMENT OF TRANSORTATION - CD - HO RELIMINARY SUBJECT TO REISION - ENTRANCE 5/30/2015 INTERSTATE 15 AND TROICANA AENUE INTERCHANGE FEASIBILITY STUDY EXHIBIT 2: 11-FOOT TAER LIMITS

7 roject I 15/Tropicana Interchange Feaibility Study FIGURE 2: INTERIM OTION 1 ANALYSIS RESULTS 2020 olume AM (M) eak (Dual exit to Flamingo) FIGURE 3: INTERIM OTION 1 ANALYSIS RESULTS 2020 olume AM (M) eak (Single Exit to Flamingo) age 7 of 16

8 roject I 15/Tropicana Interchange Feaibility Study Interim Option 2 12 foot lane under Tropicana Interim Option 2 propoe to reduce the number of G lane on I 15 to 3 prior to adding a lane for the NB CD road entrance ramp a an auxiliary lane to Spring Mountain. Under the Tropicana bridge, thi option would effectively not change the width of the propoed roject Neon layout and matche the exiting houlder and buffer. The outide G lane on I 15 would end approximately 1500 feet outh of the exiting CD road entrance ramp location. The CD ramp would enter the outide lane a it own lane and continue northbound a the 4 th G lane. Exhibit 3 depict the approximate limit of the lane drop and taper. Thi configuration wa alo teted with both a ingle lane and a two lane exit at Flamingo, with imilar reult. Traffic analyi for Interim Option 2 wa evaluated uing HCS. The network conit of 5 egment for analyi becaue of the lane reduction on the mainline before CD entrance. Figure 4 provide the NB I 15 traffic volume, lane and HCS reult that include peed, denity and LOS. Figure 5 provide the ame data, but with a ingle lane exit ramp to Flamingo. age 8 of 16

9 HACIENDA AE EXIST. BRIDGE COLUMNS ALIBABA LN. R/W DEAN MARTIN DR HO 5- S HO BUFFER OTIONAL FRANK SINATRA DR. DRO OUTSIDE G R/W EXIST. BRIDGE COLUMNS MANDALAY BAY RD. RENO AE. 2180' - LEGEND - STATE OF NEADA DEARTMENT OF TRANSORTATION - CD - HO RELIMINARY SUBJECT TO REISION - ENTRANCE 6/2/2015 INTERSTATE 15 AND TROICANA AENUE INTERCHANGE FEASIBILITY STUDY EXHIBIT 3: 12-FOOT TAER LIMITS

10 roject I 15/Tropicana Interchange Feaibility Study FIGURE 4: INTERIM OTION 2 ANALYSIS RESULTS 2020 olume AM (M) eak (Dual exit to Flamingo) FIGURE 5: INTERIM OTION 2 ANALYSIS RESULTS 2020 olume AM (M) eak (Single exit to Flamingo) age 10 of 16

11 roject I 15/Tropicana Interchange Feaibility Study NB I 15 Summary of Reult Table 3 give a egment by egment comparion of the four HCS analyi LOS reult. AM (M) TABLE 3: ANALYSIS RESULTS Analyi Segment Interim Option SEGMENT 1 SEGMENT 2 SEGMENT 3 SEGMENT 4 SEGMENT 5 No Build NA E(D) F(F) F(E) C(B) 1 (dual) NA C(C) C(C) E(D) D(C) 1 (ingle) NA D(C) F(F) F(F) C(B) 2 (dual) C(C) E(D) E(D) E(C) D(C) 2 (ingle) E(C) F(F) F(F) E(E) C(B) Both option will require retriping I 15 partially or fully, with option 2 having the leat impact. In order to preerve the number of lane on I 15, Option 1 with a dual exit to Flamingo i recommended. In order to retripe I 15 in the northbound direction, milling of the full width pavement i recommended o that ghot triping effect are eliminated. The area jut beyond the merging of freeway traffic and I 15 on ramp from Tropicana ha 3 G lane. Thi i le than the total of 5 lane minu 1 lane of the merging roadway, preenting lane balance violation. In addition, the number of approach lane i greater than the total number of lane pat the exit point at Spring Mountain and one le the number of off ramp lane at Spring Mountain. With the recommended option, exiting lane balance iue will till be preent between Tropicana entrance and Flamingo/Spring Mountain exit ramp. A noted in the Initial Concept Memo, anticipated cot are approximately $2 Million, if contructed a it own project. Combining the improvement with roject NEON may reult in a reduced overall cot for thi individual work. age 11 of 16

12 roject I 15/Tropicana Interchange Feaibility Study SB CD Choice Lane The initial concept memo identified the choice lane at the I 15/I 215 plit on the outhbound CD road a a potential enhancement to exiting condition. Thi concept added a third lane on the CD road jut outh of the exiting URR bridge tructure and include a ramp fork, ending two lane in both I 215 and I 15 direction. The intent i to improve the operation of thi ection of the CD road a it experience ubtantial congetion and delay. The concept wa preented a hown in Exhibit 4. EXHIBIT 4: SB CD CHOICE Since that time, NDOT ha requeted additional analyi of the SB CD choice lane configuration. The evaluation now include conideration of two diverging location, one at the I 15/I 215/CC 215 plit and another at the I 215/CC 215 plit. Two geometric configuration have been prepared for the analyi; one that carrie two lane toward wetbound CC 215 with an option ramp to I 215 (Exhibit 5). The other configuration plit the two lane ection into one lane ramp at the econd diverge point (Exhibit 6). Both configuration could alo extend north to Ruell Road entrance ramp, creating an auxiliary lane from Ruell to the I 15/I 215 interchange. Doing o would provide approximately 3000 feet of ditance for vehicle to weave and pre poition for their deired detination. For implicity ake, opening the third lane beyond the URR bridge wa developed for the exhibit and analyi. In order to provide traffic analyi that accurately imulate the operation of the exiting ramp and either of the propoed improvement, a micro imulation would be required. In lieu of that, the deign team approached the macro analyi uing HCS/HCM methodology in order to evaluate the exiting condition againt the propoed. Thi approach give an approximation of each, but analyi of finer detail wa not poible. Ultimately, both analye yield the ame reult due to limitation of the analyi method. age 12 of 16

13 antenna SUBJECT TO REISION TWO S WB AST EXHIBIT 5: RELIMINARY CBR TRAEL TRAEL SUNSE T RD CBR TRAEL TRAEL TRAEL ER I ER ARR I DB RR NTE BA XTE ED 0'E 126 NT TE EX 0' TRAEL CBR TRAEL TRAEL TRAEL CBR 24' 3' 24' TRAEL TRAEL 3' 5.5' I -1 5/ I ' TO GORE DEARTMENT OF TRANSORTATION STATE OF NEADA TROICANA AENUE INTERCHANGE INTERSTATE 15 AND FEASIBILITY STUDY 5/30/2015 DIERGE LOCATIONS

14 SLIT CC-215 and I-215 5/30/2015 SUBJECT TO REISION EXHIBIT 6: RELIMINARY ANNTENA SUNSE T RD I -15 / I 215 CBR TRAEL TRAEL TRAEL CBR TRAEL TRAEL DEARTMENT OF TRANSORTATION STATE OF NEADA TROICANA AENUE INTERCHANGE INTERSTATE 15 AND FEASIBILITY STUDY

15 roject I 15/Tropicana Interchange Feaibility Study NDOT provided updated traffic volume for the SB CD and Ruell Road ramp to perform the HCS analyi of the ramp configuration. Since the AM volume had ome error (due to malfunction of count tation), only the M volume were ued for analyi which wa the wort cae cenario a well. The volume for the CD road and Ramp are hown in Table 4. TABLE 4: CD AND RAM OLUMES Location 2014 M 2020 M SBCD (North of I 15 & I/CC 215 plit) SBCD to I/CC SBCD to I In order to determine the LOS for the exiting and propoed lane configuration, denitie were calculated uing Equation from HCM 2010 (page 13 27) for major diverge condition. The equation i hown below; D MD = (v F /N) D MD = Denity in the major diverge influence area v F = Demand flow rate uptream of major diverge influence area (pc/h) N = Number of lane approaching the major diverge Uing the two lane ramp, comparative LOS value increaed coniderably. The denitie for the wort cae (M peak hour) for 2014 and 2020 and are hown in Table 5 along with the LOS. Thee were compared with the no build condition for both year (2014 & 2020) and are hown in Table 6. TABLE 5: DENSITY CALCULATIONS FOR SB CHOICE SLIT Major Diverge Denity Calculation Year v F N D MD LOS 2014 M Build B 2020 M Build B TABLE 6: SB CD CHOICE SLIT LOS SB CD & I 15/215 Split LOS Location M M No Build F F Build B B No Build LOS wa determined uing HCS oftware The concept preent everal opportunitie with repect to oberved operational deficiencie and potential operational enhancement at the I 15/I 215 plit. However, a tated in the initial concept age 15 of 16

16 roject I 15/Tropicana Interchange Feaibility Study memo, even though the pecific improvement hown in the CD Choice Lane concept are meritoriou, the operational iue at the plit i compounded by further operational iue on wetbound CC 215. Traffic analyi performed during the I 15 South Deign Build project determined that without correction to CC 215 deficiencie, the ytem to ytem movement performance would be degraded. Once improvement to CC 215 are completed wet to Decatur (and beyond), it i expected that thi plit will caue delay to ytem to ytem uer. The backup congetion on the SB CD i not only due to the diverging off ramp. A majority of the congetion i due to bottle necking of the exiting 1 lane ramp to CC 215. The exiting CC 215 traffic from the SB CD i over 2000 vehicle per hour which exceed the capacity of a ingle lane exit and hence perform at LOS F. The propoed 3 lane SB CD with a 2 lane ramp to I/CC 215 will increae the capacity and improve the LOS. Alo, becaue the I 15 SB traffic from the SB CD i le than 1400 vph, the SB CD ha a higher likelihood of improved performance. In dicuion with NDOT Traffic Operation Diviion, extending the choice lane a a drop lane a hown in Exhibit 5 may not enhance operation of the ramp. NDOT ha experienced a imilar ituation on the I 80/US395 interchange where the additional lane length ha degraded ramp performance. Utilizing ingle lane ramp at the econd plit a hown in Exhibit 6 will require driver to pre poition for their deired detination, allowing traffic through the plit to move without having to merge/weave. Without a micro imulation and given NDOT experience on I 180/US395 where the propoed olution increaed delay a oppoed to reducing it the configuration hown in Exhibit 6 i recommended for conideration. When Clark County begin to deign improvement to CC 215 wetbound, NDOT hould conider coordinating with them to extend two lane further wet. CLOSING AND STUDY SUMMARY Thi memo addreed operational analyi of interim concept identified during the I 15 and Tropicana Interchange Study. The interim concept potentially provide operational enhancement of the exiting I 15 and Tropicana interchange and of I 15 in the vicinity of the interchange. CA Group ha performed a creening of thee concept and further evaluated the feaibility and compatibility of each with the current I 15 mainline configuration, planned improvement on Tropicana, exiting deficiencie in traffic operation and potential benefit of implementing thee concept. CA Group recommend implementation of Interim Option 1 11 foot lane under Tropicana (4 G + 1 HO + 1 CD on ramp/auxiliary) a an intermediate olution to I 15 congetion until the Tropicana bridge i lengthened. Initial project cot i etimated to be cloe to $2M. CA Group initial recommendation for additional tudy of the SB CD Choice Lane ha been reviewed further a part of thi interim concept memo. NDOT i encouraged to coordinate with Clark County plan to improve CC 215 wetbound to Decatur to determine whether improvement of the SB CD are feaible at thi time. It i etimated that the improvement to the fork area and ramp repreent an initial project cot of $2.8M to $3.4M. age 16 of 16