AgdaPkt 2010-06-14 - Laserfiche WebLink

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7.A Page 10 Avenue) . Subsection SA (0.76 mile, between north of 5th Avenue and south ofStb Avenue) For the detailed evaluation of alternatives, HSR expanded the three basic vertical options - elevated, at-grade (existing Caltrain grade), and below grade - to six options to better differentiate their characteristics. An overview of the six vertical options is shown below. The construction cost estimates are found in Appendix L, and are described in the AA Report as "order-of-magnitude" cost comparisons of the different design options; they do not repre.sent total costs for the project. Cost estimates sumnlarized below primarily reference the 4-track scenario only; please refer to Appendix L for additional cost estimate information. 1. Aerial viaduct . Elevated structure on columns crossing ove.r existing streets to provide grade- separated access in the community (except in the transitional area of changing vertical alternatives, and at supporting structures). . Property hnpact: to accommodate four tracks, a width of 79 feet is required. The nominal width including the necessary Temporary Construction Easement (TeE) for this option is 103 feet in subsection 4C. . Capital cost estimate: $157 million for the four-track scenario in subsection 4C. 2. Berm or Mechanically Stabilized Earth (MSE) - this is essentially a large earthen wall on top of which would be the tracks (similar to the existing Caltrain tracks in parts of southern San Carlos). · The berm option does not enhance connectivity and mobility as well as an aerial viaduct option or trench or tunnel option. From the perspective of land use~ the berm is inconsistent with adopted plans and policies~ there is strong local opposition to this type of structure; and the berm struchU'e (wall) would create a perceived barrier through this area which is not consistent with the loc.al communities' character and land uses. · This option has not carried forward in Redwood City for any subsections. · Property impact: 85 feet; 109 feet with TeE. 3. At-grade (existing Caltrain grade) . Grade separations requiring surface streets to go either over or under the tracks that remain at existing Caltrain grade. Right-of-way impacts include parcels affected by changes to the roadway profile approaching the grade separation. This option doesn't provide community access except at the street crOSSIngs. · Property impact: 96 feet; TeE minimal (construction would occur primarily within ultimate ROW). 4. Open trench · This is a shallow "box" that is open at the top, and bridged at street crossings, drainage channels, or streams. Where they cross the trench, the structures of these bridged areas would be approximately 10 feet in depth in order to accommodate existing utilities. This option does not provide community access except at the street crossings. · Property impact: 96 feet; 120 feet with TeE.