04-22-1996 Council Packet - Laserfiche WebLink

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One commentary on cost/benefit analysis stated, ”Benefit/cost analyses of most public policy decisions have been both much needed and frequently wrong....There are huge, almost always insurmountable, problems in identifying and measuring the benefits and costs. Thus it is that the value is in the concept, rather than in using it as a rigid and narrow decision rule. It is most valuable as a way of thinking and most dangerous as a formula to replace judgment in decision making...(t)here remain enormous problems in identifying and then measuring benefits and costs. The best aids are careful thinking, experience with similar projects, and recognition that the benefits and costs can be only partly quantified and that tenefit/cost analysis thus provides background for judgment- not a replacement for judgment'' 2. Traffic Analysis Procedure Forecasted traffic data is an important factor in Mn/DOTs evaluation and design of the alternatives. However, there are significant unresolved issues pertaining to the underling principles used by Mn/DOT in their traffic analysis procedure. These issues relate to the assigned roadway links and their hourly design capacity. Primary issues relating to previous TH 12 traffic forecasting include; • The traffic forecast did not include the new (1993) County Road 6/I-494 interchange in Plymouth for either the existing (1994) or future (2015) analysis. • The existing and future traffic forecast did not include the 1.4 mile upgrade of County Road 6 between TH 101 and 1-494 CR 6 was expanded from a 2-lane to a 5 lane cross-section in this area • TH 101 is a four-lane roadway running north/south connecting TH 12 and CR6 in Wayzata and Plymouth. It has previously been modeled under two-lane capacities (850 vph) • Under the Mn/DOT TSM alternative, existing and relocated Watertown Road were assigned the same roadway capacity (650 vph). The new facility, with less driveway interference, shoulders, and better roadway geometries can be expected to have a greater volume capacity and attract a greater number of vehicles. • TH 55 in Plymouth is a four-lane divided highway located approximately 3 miles north of TH 12 TH 55 was modeled under existing 1994 conditions with an average, daily traffic volume of 11.120 vehicles. Year 1994 traffic counts on the facility near 1-494 show an ADT of 46,000 vehicles This severe discrepancy suggests the traffic forecasting results may require further refinement and validation Based on the factors outlined above, it appears that past traffic forecasting may not have permitted evaluating the effectiveness of all alternatives. Previous analyses may have underestimated the capacity of CR 6 and Watertown Road to provide local access relief, resulting in possible overestimation of projected traffic volumes on TH 12. The effects of combining these new model inputs with the TH 12 alternatives have yet to be studied. ' Huefner, Robert, “Introductory Notes on Quantitative Techniques for Program Planning and Management”. University of Utah. 1985 PARSONS BRINCKERHOFF 8 w Mongiake\report.doc