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CR 90-172 Engineer's Study - Frontage Road• 0 August 14, 1990 James Geasele Engineering Supervisor 1 Y 0 A K z1 ENGINEER'S STUDY T.E. 7 Frontage Road at 12th Avenue North to traialLeieiliginekagree o What are the findings? o What are some remedial alternatives? o What is staff's recommendation? Council Report: 90 -172 Prop sed Act oar. gtaff recommends the following: lic ve t at Council accept a Phase 1 t f .c stu of the T.H. 7 Fronta e d Roa connection at 12th Avenue No t ' t act s taf to lace an irp rc��re arcect fcsr this site on theis t i s 19 9 e e Ga ita i M intact oveaaents Pr c ram . ervit . A memorandum from Nancy Anderson on behalf of the Zoning and Planning Commission was directed to the engineering office. The Commission requested that a traffic study be undertaken concerning traffic flow patterns at the problem intersection. Council at its April 17 meeting authorized such a study and Benshoof and Associates, Inc. was retained to conduct a preliminary survey. That Phase T study is complete. o Phase i Traffic Analysis from Benshoof and Associates • s 7►aa►lya 1 e , ENGINEER'S STUDY CR: 90-172 Page 2 o What are the findings? The frontage road is owned and maintained by the intersection with T.H. 7 at 12th Avenue serves as a. usaj for traffic movements both east and west on T.H, 7. paint west of Oakridge Road is limited in function (no eastbound movements). A third access at 17th Avenue both east and westbound on the highway but principally western portion of the frontage road. The design of the intersection does not meet current standards. Some delay occurs at the signalized intersection but of greater significance are the safety and congestion problems. There is limited stacking distance for queued cars, westbound vehicles on T.H. 7 turning right to return east on the frontage road cannot properly execute a turn, and westbound vehicles on T.H. 7 turning to proceed westbound on the frontage road conflict with no::ma i westbound through vehicles on the frontage road. Vehicles queued on the frontage road at times will bypass other vehicles waiting to turn south to T.H. 7 by jumping the curb on the right. The school and community center nearby continue to Y grow and this only will compound the problems. Mn /DOT has no current plans to improve T.H. 7 in this area o What are some remedial alternatives? There are some alternatives that merit consideration: Eeyi.sie: Access City, and its or access point Another access connection for benefits users only along the 1. Close the intersection and eliminate frontage road access to the highway. This would have a negative impact on access for the � and 17th Avenue would be the only access point to the ease{. on T.H. 7 2. Create a right in /out intersection. This option also access difficulties and requires extending the T.H. 7 through intersection and has a negative impact on the approach of 12th Avenue. creates median south .r . _.Rr difi.catiElD2 The green time for southbound vehicles at the intersection could be increased but would not reduce queues to significantly improve traffic flow. This option also does not address the majority of traffic conflicts. lakateglintgliMellienntj • RKt;atsa the Intersection Improvements such as widening of the frontage road and greater separation of the road from T. H. 7 would provide sufficient stacking distance for vehicles in their quest for access to the highway. However, further detachment would require acquisition of school property and could have adverse impact on the school's preliminary plans for construction of a maintenance facility north of the frontage road intersection. o Staff Recommendation? ENGINEER'S STUDY CR: 90 -172 Page 3 Staff recommends making improvements to the intersection and that such a project should be placed on the City's 1991- °1995 CIP schedule. in the meantime staff can and will be in contact with school officials to discuss such improvements, • August 13, 1990 MEMORANDUM SUMMARY BACKGROUND BENSHOOF & ASSQC6ATES INC. TRANSPORTATION AND LAND USE CONSULTANTS 7901 FLYING CLOUD DRIVE, SUITE 1 19 / EDEN PRAIRIE, MINNESOTA 55344 / (612) 944 -7590 / FAX (612) 944 -9322 REFER TO FILE: TO: Jim Gessele, City of Hopkins FROM: Mitch Wonson 471 RE: Traffic Analysis of T.H. 7 North Frontage Road and 12th Avenue Intersection - Phase I The purpose of this memorandum is to summarize the findings and recomrnendations of our traffic analysis of the intersection of the T.H. 7 North Frontage Road and 12th Avenue North. There are currently safety and congestion problems as a result of the design and "oration extremely close to the T.T. 7 mainline. A moiety of alternatives were identified and preliminarily evaluated. The preferred alternative to resolve existing difficulties is, to detach (separate) the frontage road from T.U. 7 at this location. This alternative will require acquisition of school property. It is recommended that the City work with the school district to evaluate alternative design/locations for this frontage road detachment to resolve they problems while minimizing impacts on the school. The analysis was prepared in nse to City concerns regarding safety and traffic operations at the intersection. rincipal purposes of this phase of the study were to identify existing conditions and problems, identify broad based alternatives to resolve deficiencies, and evaluate which alternatives merit more detailed study. To assist its the analysis we have held discussions with City, school district, and Mn/DOT staff and performed P.M. peak period counts and observations of traffic operations at the frontage road intersection and adjacent signalized intersection or T.H. 7. EXISTING DITERSECTION AND TRAFFIC CHARACTERISTICS Key findings concerning the existing intersection are summarized below. • The frontage reed is both maintained and owned by the City, having been 'turned back' in 1986. While this allows the City flexibility concerning potential improvements, financial participation by Mn/DOT is unlikely. 90-28 • • Mr. Jim Cisscle _7_ August 13, 1990 • The 12th Ave. intersection with T.H. 7 performs a major access function for the area served by the frontage road. Figure 1 presents the access/circulation patterns associated with the frontage road. Given the fact that the frontage road does not provide a connection to 5th Ave. /Oakridl a Rd. for eastbound movements, the intersection at 12th Ave. provides the only viable opportunity for movements to the east on T.H. 7 and to /from the south for the majority of users along the frontage road. The 17th Ave.i }Jopkins Crossroads access at T,FH. 7 provides convenient access to the east and south only for users along the western portion of the frontage road. • • The design of the frontage road /12th Ave. intersection does not meet c- urrent standards as the separation between T.H. 7 is very limited (10-15 feet). Figure 2 presents the intersection layout. This design results in the principal difficulties associated with the intersection as discussed below. • In general limited delay occurs at the intersection, as the adjacent T.H. 7 signalized intersection operates at a level of service C and all cars queued clear the intersection in any given cycle. • Significant safety and congestion problems are apparent at the frontage road intersection principally due to the design. These include: limited stacking (one car) on the approach to T.H. 7 such that the frontage road intersection is easily blocked westbound T.H. 7 vehicles turning right to return east on the frontage road cannot complete the turn if vehicles are queued westbound on the frontage road. This results in the turning vehicle backing up into the intersection. westbound T.H. 7 vehicles turning to proceed westbound on the frontage road create serious conflicts with westbound through vehicles on the frontage road. westbound through vehicles queued on frontage road bypass vehicles waiting to turn south to T.H. 7 on both the right (over the curb) and the left (in the oncoming traffic lane). eastbound through vehicles on the frontage road perform a similar bypass movement in the oncoming traffic lane. as the school and community center continue to row, these difficulties will be exacerbated. Current school plans include increased elementary school enrollment and other activities, as well as possible construction of a maintenance facility north of the frontage road intersection. Mn/DOT has no current plans for improvements to T.1-1. 7 in this area. To summarize the existing conditions, the design of the i2th Ave. /frontage road intersection and its proximity to T.H. 7 result in numerous traffic conflicts and resultant safety problems. M zg a0 c0 m 0Z > = O rTi Z 0 ' 441 ® z 0 xv 0c G _ 0 Mt -n IP CA rn z (1) C) 0 0 z "T3 (i) > rn .71 frri c -i :DI • • • • • Mr. Jim Gissele IDENTIFICATION ION O ALTERNATIVES sews... gv'sionsa -3- August 13, 1990 Three broad alternatives have been identified which might assist in resolving the identified intersection problems. These would include either dosing the north leg of the intersection with T.H. 7 completely or converting it to a right in/out only, retaffieSostekteLMOsiifiegdiellS This principally involves modifications to the tinning of the T.H„ 7 traffic signal to clear traffic from the frontage road area more quickly, ImprovernenisetoelbeeEEDLI These would include both minor improvements such as widening or bypass lance construction to detachment of the frontage road (creation of a greater separation film T.H. f EVALUATION OF ALTE.ATIVF.S The evaluation process was oriented at determining which of the broad alternatives merit further consideration and subsequent analysis and design. The findings are summarized below. Arscrto evisi ®ras Closure of the north leg of the T.}L 7112th .Ave. intersection would eliminate cunt difficulties by removing all turning conflicts and effectively eliminating the frontage road intersection. 'This option, however, wouid likely result in significant negative impacts on access for the area, particularly the school and adjacent church. All trips to the east on T.H. 7 and to the south you'd be forced to utilize 17th Ave., given the lack of frontage road continuity to the east. The reconstruction of the T.H. 7 intersection to right in/out only would result in the same cibcuitious access difficulties. In addition, a safe and effective light iniout design would require extending the T.H, H.. 7 median through intersection, reducing access to/from T.H. 7 for the south approach of i2th Ave. Given the negative impacts ors access of these alternatives, they are not recommended at this time. It is important to note, however, that long range planning by the City should include extension of the frontage road for two way traffic flow to the east to Oakrid c Rd. in some fashion. In addition, consideration should be given to terminating the cresting frontage i°oa.d intersection with 17th Ave. and realigning the frontage road to the north, possibly via Robinwood Lane/5th St. North. 1 • • Mr. Jim Gni ssele Increasing the green time for southbound vehicles at the T.H. 7 /12th Ave. intersection is not expected to reduce queues sufficiently so as to significantly improve operations at the f.oa tge road intersection. In addition, this mixiification would not resolve the majority of existing traffic conflicts. As such, it is not recommended for further analyysis. One traffic control modification which would somewhat reduce conflicts would be to prohibit right turns on red for westbound T.H. 7 traffic. This modification would hells but not significantly resolve current problems. ID* • • :41 + : 1 Road IIIie SeC lan -4- August 13, 1990 As rioted these improvements could consist of minor widening/bypass lane construction to a full detachment (separation) of the frontage road. Widerzng the roadway could improve the ability for a westbound T.H. 7 vehicle to make the turn to the eastbound frontage road and provide a "bypass" lane for eastbound through traffic on the frontage read. Creating a bypass lane for westbound through frontage road traffic could eliminate the current inappropriate bypass maneuvers. It is expected that limited addition right of way from the school would be required dependent upon the exact location of the frontage road in the existing right of way. This limited construction would provide some improvement to intersection operations, but would not resolve all current difficulties and likely not provide significantly improved operations. Detachment of the frontage road is shown conceptually on Figure 3. This detachment separates the frontage road from T.H. 7 and provides a "throat" for southbound vehicles to queue. A detachment sez;t as th;s would be expected to resolve the current significant safety and congestiea problems at the frontage road intersection. The detachment will require uistion of school property with the exact layout req�.�iring further design. Typcial trfic standards indicate a 150 foot separation from T.H. 7 to the frontage is desirable. These standards could be modified dependent upon further analysis and opportunities for redesign of the school site and /or proposed maintenance facility. To summarize, based upon our preliminary evaluation the preferred solution is improvements to the frontage road intersection to increase separation from T.H. ". it is recommended that the City pursue design alternatives for this alternative whale working closely with the school district to address both traffic concerns and site needs/usage characteristics. • • Mr. Jirn Gissele _4_ August 13, 1990 Taf ' cuitscAllodifir ions Increasing the green time for southbound vehicles at the T.H. 7 /12th Ave, intersection is not expected to reduce queues sufficiently so as to significantly improve operations at the frontage road intersection. In addition, this modification would not resolve the majority of existing traffic conflicts. As such, it is not recommended for further analysis. One traffic control modification which would somewhat reduce conflicts would be to prohibit right turns on red for westbound T.H. 7 traffic. This modification would help but not significantly resolve current I Yoblems. rantaae Road Intersectipn As noted these improvements could consist of minor widening/bypass lane construction to a full detachment (separation) of the frontage road. Widening the roadway could improve the ability for a westbound T.H. 7 vehicle to make the turn to the eastbound frontage road and provide a "bypass" lane for eastbound through traffic on the frontage road. Creating a bypass lane for westbound through frontage road traffic could eliminate the current inappropriate bypass maneuvers. It is expected that limited additional right of way from the school would be required dependent upon the exact location of the frontage road in the existing right of way. This limited construction would provide some improvement to intersection operations, but would not resolve all current difficulties and likely not provide significantly improved operations. Detachment of the frontage road is shown conceptually on Figure 1. This detachment separates the frontage road from T.H. 7 and provides a 'throne for southbound vehicles to queue. A detachment such as this would be expected to resolve the current significant safety and congestion problems at. to frontage road intersection. The detachment will require acquisition of school property with the exact layout requiring n further design. Typcial traffic engineering standards indicate a 150 foot separation from T.H. 7 to the frontage is desirable. These standards could be modified dependent upon further analysis and opportunities for redesign of the school site and/or proposed maintenance facility. To summarize, based upon our preliminary evaluation the preferred solution is improvements to the frontage road intersection to increase separation from T.H. 7. It is recommended that the City pursue design alternatives for this alternative while working closely with the school district to address both traffic concerns and site needs/usage characteristics. 12TH AVE.