California High Speed Rail through the Pacheco Pass
For the past six months, I’ve been working with AutoCad, Google Earth, and the California High Speed Rail Authority’s website with the goal of creating an up-to-date .kml file of the current proposed route for the CHSR, with specific attention to the alternative analysis. Starting with today’s post, and continuing for the next couple months, I will be presenting the 2010 proposed alignments and analyzing the alternatives that the CHSRA will carry forward. The purpose of these kml files is not to show the exact route but rather to help gain a general overview of the alignment alternatives and the types of structures necessary for each alternative.
There are only three places on the San Jose-Merced section where the CHSR horizontal alignment has been finalized: first, between San Jose and Morgan Hill; second, the climb out of Gilroy up to San Luis Rey Reservoir; and third, the brief flat section in the San Joaquin Valley from the California Aqueduct to the a few miles east of I-5. Other than that, there are 32 possible horizontal alignments on the roughly 100-mile segment of the route between Diridon Station (situated above the current station) and a few miles west of Chowchilla.
The CHSRA settled on the SR-87/I-280 aerial approach to Diridon Station after eliminating seven alternatives. This segment is going to have significant constructability issues due to business displacement and a gigantic aerial structure over both freeways. The alignment avoids much of downtown San Jose at the expense of the Almaden neighborhood.
The alignment will then descend to run at-grade next to the Caltrain tracks. The Caltrain tracks, owned by the Peninsula Corridor Joint Powers Board, will need to be shifted east to accommodate the two CHSR tracks. After the PCJPB ownership ends near Pullman Way in San Jose, the tracks ascend to an aerial structure, staying outside the right of way of the Union Pacific Railroad (UPRR), a national freight railroad that has been understandably reluctant to share their right-of-way with the CHSRA. The alignment will continue adjacent to the UPRR tracks until Morgan Hill.
At this point, two horizontal alternatives diverge: one takes the tracks along US 101, the other along the east side of the UPRR right-of-way. These two sections will connect with one of two alternatives in Gilroy: an alternative that runs through and has a station in downtown Gilroy (with an option for a trench), and an alternative that runs east of Gilroy with a station east of the outlet stores on Leavesley Road. The East of UPRR alignment will require a relocation of the Monterey Highway. The CHSRA prefers the UPRR alternatives because they follow existing transportation corridors and provides the quickest time between Morgan Hill and Gilroy (8.75 minutes). The trench option, demanded by the City of Gilroy to reduce visual impacts of an aerial structure, would create a 5-mile, 185-foot wide trench, but would require use of the Union Pacific right-of-way.
The east of Gilroy alternatives are not preferred, but are carried forward because of reduced residential displacements and to placate the City of Gilroy. Unfortunately, the East Gilroy alternatives would place a station on Leavesley Road. A station here would not only create a visual impact in this now-agricultural area, but also reduce connectivity with Caltrain and a future commuter rail line to Monterey.
East of Gilroy, the construction team will face “steep terrain, narrow valleys, and engineering challenges.” In this Pacheco Pass section (chosen over Altamont for a more direct route to the Bay from Los Angeles), bridges in excess of 300’ in height as well as intrusion into the San Luis Reservoir, the San Joaquin National Cemetary, Pacheco State Park, or Mt. Hamilton Nature Conservancy were deemed unallowable. Using Quantm, a computer model to identify effective alignments, the Authority picked one alignment and a deviation near the San Luis Rey Reservoir (“Close to 152” Alternative). Both alignments include 8 tunnels, with the longest tunnel being 22,700 feet (4.3 miles) long.
The San Joaquin Valley subsection has been reduced to two alternatives along Avenue 21 and 24 and Henry Miller Avenue. Avenue 24 has more severe impacts in Chowchilla where the route calls for a wye connecting the Los Angeles and Sacramento branches, but has eight less grade separations and effects 81 less acres of farmland when compared with the Avenue 21 alignment.
The San Jose to Merced section will face significant challenges in working with the Union Pacific Railroad and the cities along the US-101 corridor between Gilroy and San Jose. The Pacheco Pass section will present some of the most difficult engineering challenges along the entire alignment.