Agenda - Council - 04/11/1995 - Laserfiche WebLink

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'1 I I I I I I I I I I I I I I I I I I CASE # UPDATE ON 153/155 AVENUE N.W. By: Steve Jankowski, City Engineer Background: You will recall th~tt in June 1994, we received a preliminary engineering report on the alignment for 153/155 Avenue~etween Variolite and Armsu'ong Boulevard. The consultants, RLK Associates Ltd., indicated th~[t this alignment could be constructed with only the installation of a retaining wall to prevent encro{tehment of the roadway into the wetland. Subsequent to an actual wetland delineation, whicSresulted in the wetland being approximately 25 feet further inland than had been anticipated, I reported to the Road and Bridge Committee at the February 14 meeting, that the alignment described in the preliminary report could not be constructed without impacting the wetland. I indica/gA to the Road and Bridge Committee at that time that the consultants and myself would be discussijag alternatives with the County and State in an attempt to attain an alignment that would meet our transportation needs without impacting the wetland known as Jeglands Marsh. At this point, oui efforts have resulted in two basic alignments. The £u'st option most closely conforms to the o,{'iginal alignment described in the June 1994 preliminary engineering study. This alignment consists of the double S type curves that would convey the traffic from 155th and Variolite directly po a cross intersection at 153rd and Armstrong. In order to retain this alignment, without encroacl~ng on the wetland, a reduction was made in the design speed of the approach curve closest to/~rmstrong Boulevard from 35 miles per hour down to 30 miles per hour. in addition, the crosjs-section of this roadway was reduced from 40 feet, in the original design, to a range of between! 32 and 38 feet, with parking being restricted along the entire north side of the roadway and alo4g the curves on the south side of the roadway. This alignment also reduces the available properOb, remaining for development between 153/155 and Armstrong Boulevard to between 150 and ~200 feet. This represents a reduction of approximately 50 feet in depth from the original prelimin ..a~ engineering design. A second option ~r avoiding impact to the wetland consists of extending 155th due west along the section line until Intersecting with Armstrong Boulevard. This alignment would require the use of Armstrong Boule$,ard between Lane and 153rd Avenue to carry east/west traffic wishing to travel on 153/155. A ~ajor disadvantage of this option is that it creates conflicts with accelerating and decelerating 1531155 traffic, with faster moving traffic on Armstrong Boulevard. This speed differential can bi as high as 35 miles per hour when 153/155 traffic reaches its maximum speed on Armstrong. Tp mitigate this safety concern, this alternative would include the construction of two additional tr~ivel lanes on this segment of Armstrong Boulevard to facilitate the differential traffic speed. Th~s alternative would also require the closure of 154th Lane west of Armstrong to prevent through t~affic from moving from 155th down 154th Lane. A variation of this alternative would be the eon~;truction of extra lanes on Armstrong Boulevard with the addition of signalized intersections at l~5th and 153rd Avenues which would eliminate the safety concern associated with the disparate spe~s of 153/155 vehicles using Armstrong Boulevard, as they would be protected during their acceleration and deceleration by stopping traffic on Armstrong. The delay caused by the traffic on Arm3trong from this alternative would be a negative aspect of this option. Below is a summary of estimates of total project costs which include project overhead of 25 percent with the oyiginal alignment identified in the preliminary engineering report and each of the alternative options discussed above.