3C Public Hearing 2010 0503 - Laserfiche WebLink

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TJIQ~A Tran~por~tion Cansuldnts Analysis Approach The analysis is straightforward and logical. It supplements the current transportation financing program already in place in San Leandro. This report was prepared by completing the following steps. 1. Define Trips That Lead to the Need for Improvements The I-880 freeway was designed and constructed over 50 years ago, and the Marina/I-880 interchange is deficient in terms of clearance above the I-880 mainline as well as in the ability to accommodate ever-increasing traffic volumes on Marina Boulevard and the ramps to and from Marina Boulevard. Both the loop and diagonal off ramps merge with through traffic on Marina Boulevard, and they have reached capacity. In addition, the distance between the diagonal off ramps and the downstream signalized intersection is only a few hundred feet, so drivers exiting the freeway intending to turn left at these signals must weave through several lanes of traffic without adequate weaving distance, and this leads to congestion and accidents. Finally, the unsignalized left turns onto the on ramps are significantly congested during peak hours with traffic backing out of the left turn lanes into the left-most through traffic lanes. Therefore, all traffic on Marina Boulevard between Merced Street on the west to Wayne/Teagarden Street on the east plus all ramp traffic contributes to the need for interchange improvements. 2. Use the Countywide Model for Analyzing Trips Using the Interchange The most recent version of the Alameda County countywide model as adapted for use in the Draft Environmental Impact Report (DEIR) for the combined ICI and Kaiser Permanente projects was used for this study as the model was calibrated for use in the local area. The model has both 2005 (Existing) and 2030 (Future) scenarios. The model as adapted for the DEIR includes accurate land use tabulations for current conditions as well as forecasts for 2030 conditions for the immediate area near the interchange as well as for Alameda County and the entire Bay Area. 3. Division of Trips by Category As this study will be used as a basis for a benefit assessment area or supplemental traffic impact fee, it is necessary to define trips using the interchange due to local development plus existing trips and regional traffic. The model is quite useful in this regard. Trips from new development having an origin or destination within San Leandro are those for which fees can be assessed. Existing trips cannot be used for the imposition of fees, nor can through traffic (trips that both begin and end outside San Leandro). Each quadrant of the interchange was evaluated with respect to the level of traffic contributed. It was found that 80 percent of the growth in traffic at the interchange is expected to come from the quadrants. Locations in San Leandro that are relatively remote from the interchange contribute very few trips and are not proposed for inclusion in the impact fee area. Only those development projects within the four quadrants defined in Figure I are likely to contribute a significant proportion of new trips to the interchange, thus only this area is defined as the impact area and is the subject of supplemental traffic impact fees.. 4. Peak Hour Trips as Basis The peak hours are the times of the day where interchange capacity deficiencies become problems. Therefore, peak hour traffic is used as the basis for calculating trips using the interchange. There are deficiencies in both the a.m. and p.m. peak hours, so no differentiation is made between the two; rather, all trips in the a.m. and the p.m. peak hour are added together to define the total number of trips using the interchange. Page 4 Final Report - Tro~c Impact Fee Analysis for I-880lMarina Interchange Improvement November 12, 2009