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.

The 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 Jose line.