Technical Construction Information
Overview
The Caldecott Improvement Project involves constructing a two-lane fourth tunnel (or bore) north of the three existing tunnels. The new tunnel will be 12.58 meters (41.25 feet) wide, and 1,033 meters (3,389 feet) in length. Seven cross-passages will connect the third and fourth bores and serve as emergency exits. In addition, the project includes the following elements:
- Construction of retaining walls and temporary and permanent soundwalls
- Various roadway improvements
- Demolition of the existing maintenance building and construction of a new two-story operations and maintenance building
- Installation of operations, communications and emergency systems
The geologic conditions along the tunnel alignment consist of steeply dipping marine and non-marine sedimentary rocks of the Middle to Late Miocene Age, comprised of sandstone, shale, chert, mudstone, siltstone, and conglomerate. The structure of the rock mass varies from blocky to crushed, and the average unconfined compressive strength of the intact rock for various geologic units varies from 1,400 psi to 7,000 psi. The fracture spacing varies from very wide to crushed, but is typically close to crushed. The tunnel alignment crosses four inactive faults which occur at contacts between geologic units. These fault zones vary in width from 80 to 230 feet and the rock within the fault zones is typically moderately fractured to crushed.
Upcoming Meetings
None
Recent Meetings
- Contractor Outreach and Small Business Networking Event: May 19, 2008
Please click to view the meeting materials for this event. - Small Business Outreach Event: February 25, 2008
Please click to view the meeting materials for this event.
| Technical Documents |
| Biological Opinion |
| Construction Requirements |
| Geologic Data |
| Preliminary Drawings |
Bidding Process Schedule
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