Webster Street Tunnel
TOTAL IMMERSED LENGTH: 732 m
DEPTH AT BOTTOM OF STRUCTURE: 25 m
HEIGHT:11.27 m (O.D.)
WIDTH: (circular)
FABRICATION METHOD: Constructed in a graving dock excavated 2 miles from the project site. Two elements were constructed per cycle. A 70 ton stop-log gate, which could be removed by a floating crane, was used to permit the elements to exit the graving dock.
DEPTH AT BOTTOM OF STRUCTURE: 25 m
HEIGHT:11.27 m (O.D.)
WIDTH: (circular)
FABRICATION METHOD: Constructed in a graving dock excavated 2 miles from the project site. Two elements were constructed per cycle. A 70 ton stop-log gate, which could be removed by a floating crane, was used to permit the elements to exit the graving dock.
between Oakland and Alameda, California,
United States
California Division of Highways
Pomeroy-Bates and Rogers-Gerwick
61m
732m
25m
Project construction
1962-04-30
12
One tube, two lanes
11.27m (O.D)
circular
see below
Constructed in a graving dock excavated 2 miles from the
project site. Two elements were constructed per cycle. A
70 ton stop-log gate, which could be removed by a
floating crane, was used to permit the elements to exit the
graving dock.
project site. Two elements were constructed per cycle. A
70 ton stop-log gate, which could be removed by a
floating crane, was used to permit the elements to exit the
graving dock.
During fabrication in graving
dock
dock
Element first brought to 100 tons positive buoyancy with combination of dry ballast
spread on roadway and water ballast in tanks under roadway. The 100 tons were offset
and a 50 tons negative buoyancy was developed using water sprinkled on the dry
ballast. Derricks on each end supported this modest load and lowered the element in
place. Wood chips were used to extend the dry ballast volume.
spread on roadway and water ballast in tanks under roadway. The 100 tons were offset
and a 50 tons negative buoyancy was developed using water sprinkled on the dry
ballast. Derricks on each end supported this modest load and lowered the element in
place. Wood chips were used to extend the dry ballast volume.
Tremie concrete joints
Membrane with timber protection
Placed on temporary supports with capacity to take section ballasted to 300 tons. Sand
placed with tremie pipe bent to direct ballast under element. Additional turbulence at the
end of the pipe was produced using a water jet. Each element was bedded into the
original deposit of sand by ballasting to more than 600 tons. This weight was sufficient
to guarantee failure of the temporary support after a minimum settlement of 10 cm.
Actual settlements were only 2.5 cm, assuring that the load was picked up by the
bedding. In the channel 13,000 tons of iron ore were used to provide additional ballast
because sand ballast alone could not provide the required weight in the available
vertical distance.
placed with tremie pipe bent to direct ballast under element. Additional turbulence at the
end of the pipe was produced using a water jet. Each element was bedded into the
original deposit of sand by ballasting to more than 600 tons. This weight was sufficient
to guarantee failure of the temporary support after a minimum settlement of 10 cm.
Actual settlements were only 2.5 cm, assuring that the load was picked up by the
bedding. In the channel 13,000 tons of iron ore were used to provide additional ballast
because sand ballast alone could not provide the required weight in the available
vertical distance.
Reinforced