Agenda - Public Works Committee - 02/18/2003

Home

P.W. CASE # CONSIDER STREET WIDTHS IN NEW SUBDIVISIONS By: Steven J. Jankowski, City Engineer Background: The Village of Sunfish Lake Planned Unit Development (PUD) has proposed street widths which fall below the City's residential street standard. Discussion of this proposal should begin with a review of the rational behind the City's current width standards. Ideally, an urban residential street might provide space for parking on both sides and through traffic in both directions. A typical traffic through lane is generally designed to be 12 feet wide. On street parking lanes varies between 6 to 9 feet. Figure A represents an ideal cross-section for a residential City street and illustrates a requirement of 42 feet from back of curb to back of curb. Realizing that the ideal section illustrated in Figure A does have adverse environmental and social impacts, the current City standard has sealed back the width demands from this idealized section. Figure B represents the current City standards. Reducing three feet from the travel lanes and two feet from the parking lanes is a significant compression over that of the idealized street section. This standard functions satisfactorily because of the fact that parking on both sides of the street is a relatively infrequent event, and free parking lanes give flexibility to the street use. With the proposal by the developer to prohibit parking on one side of each residential street, Staff would be supportive of reducing the street section to 28 feet wide as illustrated in Figure C. The difference from current City sections is the elimination of a six-foot parking lane, and an increase in one foot in each traffic lane. The increase in travel lane width is deemed necessary to compensate for the loss of flexibility provided by the second parking lane. During winter months snow is plowed only to the gutter line. Furthermore during snowy periods, high snow banks result in the loss of up to several feet along the pavement edge and vehicles tend to park farther into the street to allow passengers to exit the vehicle. These conditions were observed to some degree during the recent bus trip to Liberty on the Lake in Stillwater. The developer is also proposing to have one way streets with parking restricted on both sides. This will occur in two locations, on the main entry street and on the eastern street with a large green space separating northbound and southbound traffic. Since all additional lanes have been eliminated, there is no flexibility left in the roadway section. Careful consideration must be given for emergency situations, including snow, disabled vehicles, road repairs, etc. Staff supports a road width of 20 feet, which provides a six- foot area for emergencies. It should be noted that all of the sections shown illustrates the use of surmountable curb which extends one foot beyond the flow line of the gutter. The recommended street section may be further reduced by using straight-back curb in place of surmountable. Since the width of the curb back is six inches for straight-back curb, a one-half foot reduction may take for each curbline replaced with straight-back curb.