The Altamont alignment begins in Redwood City, just south of the Redwood City Caltrain station.
The high speed line begins to descend to pass from the Caltrain right-of-way at Redwood Junction to follow the Caltrain JPB-owned Dumbarton Branch to Fremont.
The railway remains below grade, in an open cut, from
the Caltrain line to the existing US101 undercrossing. Local streets
pass over the line, and the right-of-way is well landscaped. If
desired, a pair of loop tracks can serve a new station for local trains
near Middlefield Road.
After passing over US 101, the railway remians at
grade, with landscaping and soundwalls protecting the residential
neighborhood to the south side of the tracks. Willow Road (SR 84) would
pass under the tracks, as would University Avenue.
To cross the bay, a new high-level bridge would
probably be required to replace the existing Dumbarton rail bridge.
There are currently plans to introduce a new transbay rail service to
the line, but frequent high speed services would need to be free from
the possibility of prolonged bridge openings.
What might a new bridge cost? The 6-lane Dumbarton
highway bridge was built in 1984 for $70 million. A rail bridge
would be roughly 1/3 the width of the highway bridge, but would be
about the same length and provide the same vertical and horizontal
clearance over the bay. Using Caltrans'
construction cost index, the highway bridge would cost about $140
million in today's dollars.
Building a new bridge for rail would allow the existing
rail bridge to be removed, improving navigation on the bay. Rebuilding
the approach embankments could include short trestles to help restore
some of the bay's natural tidal flow. It is assumed that construction
of a new bridge would provide funding for many environmental
mitigations and enhancements.
Once across the bay, the railway would run at grade
across the salt ponds in west Newark. The alignment does not pass
through any of the properties targeted for restoration.
In the image above, the line
would run parallel to the high tension powerlines, and platform loops
would be provided in this area for a Newark station for local trains.
The railway continues along the powrline corridor,
before ascending an aerial structure to pass over the Union Pacific
Mulford line and some industrial streets. Once across Cherry Street,
the railway follows along an industrial rail spur, parallel to Stewart
Street. Here, the line descends from aerial into a cut and cover tunnel
under Interstate 880 and across Fremont to join the line from San Jose.
The line across Fremont will take advantage of an
existing powerline corridor. The trains will run in a cut and cover
tunnel, completely out of sight. Additionally, the powerline that now
cross the city will be placed underground, and the corridor landscaped
as a linear park.
Peninsula line meets the San Jose line at the Fremont station. More
details soon, but let's continue on the journey by describing the San