Peter, a regular commenter here at the California High Speed Rail Blog, attended last night’s meeting in San José regarding the Diridon to Tamien segment, which runs through the Willow Glen neighborhood. There has been a lot of debate about how to construct this particular segment, including a desire for a tunnel, so this meeting is of particular interest. Below is Peter’s take on the meeting. You can find the meeting boards here and the presentation here.

Aerial Alignments

The current program alignment is to run an aerial (41 foot max to base of aerial) from Diridon Station literally above the current UP/Caltrain tracks. Once the aerial crosses over 280, the plan is to drop the aerial down until it is at grade with the current UP/Caltrain tracks on a berm with retained fill as it runs through the Gardner neighborhood along Fuller Ave. As the tracks approach 87, the plan is to raise them up on an aerial again, which will pass over 87 and again be routed above the current Caltrain tracks to Tamien and beyond. I spoke with an engineer who stated that the staff is currently leaning toward running the HSR tracks through Gardner south of the current Caltrain tracks (this is all on pages 8 and 9 of the exhibit boards). This same engineer (I believe) stated that there would likely be no entire houses taken, but at least one property would lose a few feet of its backyard. Also, the portion of Fuller Park that encroaches on the current Caltrain ROW would be taken back to make room for the 4-track alignment.

The 280/87 alignment is to fully run on an aerial from Diridon Station in a left-hand curve toward the 280/87 interchange. As the aerial crosses the 280 median it begins to curve to the right. It crosses 87 and the right-hand curve continues to basically follow the Guadalupe River, and then it again curves left to line up with Tamien Station and follows Caltrain above the same as the program alignment does (this is on pages 10 of the exhibit boards). In the presentation, they discussed the issues with building the 280/87 option. The primary issues are column placement and the need to maintain freeway operations during construction. The options discussed were a “simple” aerial with frequent column placement, what looked to me like a reinforced aerial enabling less frequent column placement, and a combination of reinforced aerial and a section of “signature spans” as the alignment crosses the freeways. The City of San Jose, having suggested the 280/87 alignment to begin with, if I recall correctly, is especially interested in the signature span option.

Along both alignments, you will notice that the aerials are quite high throughout. This is based on the request from the community to make the ROW more permeable and appear as less of a barrier.

Speed along both alignments would be severely restricted due to the curve radii. An engineer I spoke with (some one who told me they were leaning toward placing the HSR tracks south of the Caltrain/UP tracks through Gardner) stated that HSR would be going around 45 mph through Gardner. During the presentation one of the panelists said that the maximum speeds would be around 50-60 mph. I am guessing that the discrepancy between the numbers is due to the fact that it is better to promise a less desirable number and deliver something better than vice-versa. The 50-60 mph may also be the maximum speed along the 87/280 alignment.

The station for the aerial alignment is going to have 9 platform tracks (5 Caltrain and 4 HSR), and I assume there will be a separate platform track for Amtrak/UPRR. Add to that the VTA tracks and BART, and you have a 14-track total station.

They discussed two possible architectural designs for Diridon Station (which can be found on pages 8 and 12 of the meeting boards). One appears to have been copied from Oriente Station in Lisbon. This was meant to give the station a more permeable feel. The other design has a very different look to it.

Tunnel Alignments

The tunnel option is what most people were interested in, and about half of the meeting was devoted to discussing the tunnel and the issues regarding constructability and operations.

The tunnel being studied is essentially the Downtown Tunnel proposed by the City of San Jose. There were two other tunnel options put forth by community members, namely “Thread the Needle” and the “5100 Meter Tunnel”. These have been withdrawn, primarily due to constructability issues that would have placed the underground station directly underneath Diridon Station, negatively impacting its operations during construction. The Gardner community agreed with the Authority that the Downtown Tunnel would serve the same purposes as the other two tunnels and had no objections to withdrawing them.

The tunnel would begin right around Tamien and descend into two single-track 32′ diameter bores dug by TBMs. The single-track bores would be split into two tracks each, and the passing tracks would continue past the station on the outside. The station itself would be mined and excavated using Sequential Excavation Method/New Austrian Tunnel Method (SEM/NATM) (this is on page 20 of the presentation). The station would have to be 1380 feet long, 70 feet wide and 40 feet high. The primary issues this would cause are groundwater problems, requiring a very complex soil stabilization process, possibility of cave-ins, and construction time. The tunnel engineer stated that the excavation of the station alone would take over TEN, yes, that is ONE ZERO years (let’s say construction starts in 2013, that would place completion time sometime after 2023?????).

Other issues with the tunnel would be maintaining the stability of the support pilings for 280, poor (unstable) soil for tunneling, groundwater issues, tunneling under both Los Gatos Creek and the Guadalupe River, fire access, evacuation issues (deep station, no elevators or escalators in emergency, etc), extensive surface impacts at entry and exits points of the tunnel, etc.

The cost of the tunnel would be prohibitive, estimated to be $3 billion at this point. This is the same cost that BART is looking at for its tunnel beneath Santa Clara St.

All in all it was not a pretty picture for tunneling. Even the council-member from City of San Jose that I could see was nodding his head sagely when all the problems with tunneling were being listed. The only advantage for the tunnel option would be higher approach speeds and higher speeds for the through tracks.

The tunnel engineer that was present at the meeting was local, having grown up in San Jose. He seemed sufficiently knowledgeable to address this meeting, although he did not discuss any major tunneling projects he had engaged in. I didn’t hear him mentioning any bored tunnels, although he mentioned a local tunnel he had worked on (unsure of the tunnel construction method). Given that they won’t actually be building a tunnel (or so I hope; God help us if they do), I’m not too worried about his experience. They would probably hire some experienced tunnel engineers to actually build the thing.

Panel Discussion

People were wondering how loud the trains would be. The Regional Project Manager stated that they had sent teams to both Spain and Taiwan to get noise values for different types of trains. Spain made sense to me, as you can study the original TGV design, the Velaro, and the Talgo 350. Taiwan made sense as well, as you can study the 700T Shinkansen, while assumably getting the noise values minus the Japanese mitigation measures. My guess is that they wanted to compare one European modern EMU with a modern Japanese EMU. They are working with the FRA to update the FRA’s HSR noise evaluation handbook (if you will recall, the handbook only includes older, earlier generation HSR trains). The results of the noise study should be released in the next couple of months, so we have something else to look forward to. The community member on the panel expressed concern over the peak noise and frequency of trains. Obviously this will not be an issue in Gardner, especially not if the trains are limited to 45 mph.

Someone asked why HSR and BART could not simply swap tunnel depths. Apparently there are four major issues preventing this from happening. First, because BART would then have the same problems regarding access and safety that HSR would have. The bigger issue is that if HSR tunneled shallower than they are looking at, they would not be able to use TBMs and would have to use cut-and-cover, which would obviously be much more disruptive than boring. HSR would also be too shallow to go underneath the 280 freeway pilings, and BART would have difficulty realigning itself with the Caltrain ROW to get to Santa Clara.

The staff is researching other deep tunneled station and have not come up with an example of an HSR station that was dug that deep. They briefly discussed the psychological effects of such deep stations, and stated that no one had done any studies as to how having such a deep tunnel would affect ridership from a purely psychological basis. They also discussed that such a deep station would make transferring to other modes of transportation at Diridon more difficult and less desirable, with negative impact on ridership at the station overall.

There was a discussion of vibration caused by trains, which Bob Doty and some others discussed by explaining how the HSR trains would be lighter and cause less noise and vibration from wheel-track interaction.

The community was concerned with impacts on existing properties in terms of construction noise vibration. The panelists punted that issue down the line, stating that that would be studied in the EIR.

Bob Doty corrected a poorly worded reply by an Authority panelist to a question regarding horn noise. The Authority panelist had stated there would be no horns on HSR, and Bob Doty corrected him by saying that the HSR trains would have horns, but would not sound them at grade crossings, because there would be none.

The Draft Project EIR is due to be released in early 2011, if I understood them correctly. The Draft Program EIR is due to be released at tomorrow’s CHSRA board meeting. The 45 day comment period would begin on March 11.

There is a very odd proposal floated by the community for the so-called San Jose Split alignment. This would split off the station tracks around Tamien and have them follow the general tunnel alignment discussed above. The through tracks would follow 87 on an aerial (I assume, it was never fully explained) and join up with the station tracks further north. To me, this would seem to be a combination of the worst of both worlds. You would still have to tunnel and mine a station just as large as with the regular tunnel alignment. At the same time you would have to somehow construct an aerial following 87 and at some point link them up further north. Bob Doty nearly laughed when he heard this suggestion. His objection was that this would severely constrict the operator’s flexibility and would cause major problems if there was a track blockage. Some more knowledgeable railroad people can explain that to me.

Bob Doty stressed a number of times that the operator will want the most flexibility possible built into the system, hence the separate bores for the through-tracks around the tunneled station.

After the panel discussion, I tried to speak with Bob Doty about some of the issues raised on Clem’s blog regarding FFSS or SFFS and CBOSS/ERTMS and how those choices meshed with maximizing flexibility, but he was inundated by crazy people. I did overhear him stating that Caltrain is looking at equipment to run at up to 110 mph.

by Peter