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2006 PMP . 11/9/2006 Page 2 DISCUSSION ~ierns COllD/Lake Johi:mu.a BoulevargJnl<;rs.~stion The t()lIowing describes the tactors considered during the design of the intersection at Siems Court and l.ake Johanna Boulevard. Prior to construction. the width of Siems Court tlared out from approximately 2S feet to approximately 70 feet at the inkrsection. Traveling northbound on Siems Cmlli, there was a very poor line of sight to the east because of the tree-lined embankment on the corner and also due to the curve and incline on Lake Johanna Boulevard. The existing angle ofthl: I:enterlines of Lake Johanna Boulevard and Siems Court intersection created a 40 degree angle rather than a 90 degree angle, which is the standard design for intersection alignml:nt. The existing design created a difficult angle for a vehicle maneuvering from Lake Johanna Boulevard cast onto Siems Court south. Also, the grade ti-om Lake Johanna Boulevard on to Siems COLlli varied from very steep on the west side of Siems Court to more gradual on the cast side. The drastic road grade was a result of the al:ute angle of this intersection. Through multiple neighborhood meetings and a review pfthe feasibility report, the City Council approved a 22 I(lot street width tor all roadways in this neighborhood. With the street width set . at 22 teet, URS and City staff set out to improve three aspects of the intersection: . to create longl:r site lines tt)r the right turn maneuver from Siems Court to Lake Johanna Boulevard; . to improve the angle ofthl' intersection; . to provide a better grade transition between Lake Johanna Boulevard and Siems Court. As a result of the 22 f()ot street width, the intersection is significantly narrower. This, along \vith some ditch tilling. helped to provide the room needed to shift the inkrscction west to square up the intersection. It also aIlO\ved tl.)r better sight lines to the east on Lake Johanna Boulevard by providing more room between the north bound lane and the tree-lined embankment. Providing an intersection that is closer to a 90 degrl:c angle allcl\vs t(lr a better range of hl:ad motion to the !en and to the right bet()re a driver makes a turning movernent from Siems Court 011 to Lake Johanna Boulevard. The last design improvement provides a smoother transition in grade on Siems Court. There \Vas an opportunity to create a longer. tlatter grade at the transition Irom Lakl: Johanna Boule\ard to Siems Court by cutting the proposed road elevation starting approximately SOO feet south on Siems Court, all the way north into Lake Johanna Boulevard. This slightly reduced a "hump" in the roadway coming into the intersection and also allO\ved Ii)r the construction of a landing by the stop sign. The lamling has a more consistent grade in all spots across the road and gradually transitions into thl: hill. A typical design fi.-n- inkrsection corners is either a 15 fout or a 20 ftlot radius. Siems Court is . dl:signed with a lO It)(lt radius 011 the east side and a 25 f<.lot radius on the west allll\ving It)}" more room It)r turning movements.