Building & engineering news . GENERAL PLA/V and PROFILE ment district at the west end contains 4,000 acres, mostof which is in large holdings, now subdivided into re-stricted resident tracts. This district was assessed from1-Lc to 3 l-2c per square foot—depending on the estimatedbenefit to be derived from the tunnel—for 85 per cent ofthe total estimated cost of the work and necessary landsfor right-of-way. The section about the east portal iswell developed and the assessment district therein is rela-tively small, about 650 acres. In the event of the construction of a subway it will con-nect wi
Building & engineering news . GENERAL PLA/V and PROFILE ment district at the west end contains 4,000 acres, mostof which is in large holdings, now subdivided into re-stricted resident tracts. This district was assessed from1-Lc to 3 l-2c per square foot—depending on the estimatedbenefit to be derived from the tunnel—for 85 per cent ofthe total estimated cost of the work and necessary landsfor right-of-way. The section about the east portal iswell developed and the assessment district therein is rela-tively small, about 650 acres. In the event of the construction of a subway it will con-nect with the present construction at the Eureka ValleyStation, and the easterly portal of the tunnel and the ap-proach thereto will be used for surface connection. From the easterly portal the tunnel grade is fof adistance of 600 feet and for the succeeding 1,075 feet thegrade is and is then +. for 6,70rt feet, from whichsection to the west portal, a distance of 3,300 feet, thegrade is The east portal is located at the westerly end of Mar-ket street, the main business thoroughfare of the city jnirchased a 90-foot right-of-way. extending from the end of Market street, which, on the comple-tion of the tunnel will be paved as a portion of the Marketstreet extension, and will connect with a boulevard overthe Twin Peaks into the residential district at the westportal of the tunnel. This boulevard, now under con-struction under a separate contract, has a maximum Types of Tunnel Liniii!::. For the first 1,665 feet, with the exception of 300 feetof th? Eureka Valley Station, owing to the slight raisein the ground surface and the shallow cover obtainable,a double tube subway type of structure was adopted, con-sisting of a flat l)ottom 22 inches thick: side walls 21iuches thick: a 12-inch centi-al wall and a flat slab top 18inches in thickness. This is of reinforced concrete ANU ENGINHIEIUNO NEWS WVmIi coiiBti-uction. as are all s
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