31 May 2009

Caltrain Does the Right Thing: Nothing

For a few months after the passage of Proposition 1A in November 2008, it seemed as if Caltrain was conducting business as usual on its capital improvement program. They are finally showing signs of waking up to HSR and its implications for the numerous capital projects in their pipeline. (photo by PBO31)

In April, Caltrain placed the renovation of the South San Francisco station on hold. This $50 million project, fully funded and at the 90% design stage--the shovel doesn't get any readier--was shut down at the last minute over uncertainty in the plans for HSR and the future configuration of the Union Pacific freight yard located there. The project will resume when more is known about detailed HSR plans for the area, probably within the next two years.

Further south and for the better part of the decade, Caltrain had plans to replace century-old, seismically unsafe, low-clearance bridges just north of downtown San Mateo. These antiquated bridges, crossing over Poplar, Santa Inez, Monte Diablo and Tilton avenues, are so low that even the Google Street View camera car nearly crashed into one. The work on this $27 million project was to start this summer. Not only would these four bridges need to be rebuilt and expanded for HSR, but they are also located in an area where the future vertical alignment of the tracks is highly uncertain, depending on how the new tracks are routed through downtown San Mateo. A San Mateo resident rightly complained about the disconnect. Recently, Caltrain announced they were opting for a better approach, consisting of a basic seismic retrofit and continued maintenance to extend the lifetime of the bridges just long enough to find out what will happen with HSR.

As part of their announcement, they stated: Caltrain is assessing its extensive capital program to better coordinate with high-speed rail and to make certain that today’s investments are not deemed obsolete in the near future.

Better do it right than do it twice.

23 May 2009

The Shape of Palo Alto

Several years ago, the city of Palo Alto commissioned a public art work entitled The Color of Palo Alto. At considerable expense ($75,000), artist Samuel Yates set out on a techno-artistic quest to determine the exact shade of Palo Alto. In a similar vein, and bearing in mind that artistic form is more than just color, we set out to determine the shape of Palo Alto.

Why does the shape matter? While the area around the tracks in Palo Alto is pretty flat, small variations in the terrain do have an effect on how the high speed rail project will be configured as it crosses through town. The vertical alignment of the tracks must not only conform to the surrounding grade, but it must be routed over or under every creek, road, pedestrian or bike crossing while conforming to acceleration limits imposed by passenger comfort as well as train stability and performance.

There have already been strong hints as to what shape this vertical alignment might take, as previously discussed in Focus on Palo Alto. As part of its program-level EIR/EIS, the California High Speed Rail Authority produced a set of maps of the Caltrain corridor that fueled a firestorm of controversy in Palo Alto, with residents worried that raised tracks would form a Berlin Wall and divide the city. While the CHSRA now professes to consider all vertical alignment options for its project-level EIR/EIS, ranging from tunnels to elevated tracks, there aren't that many feasible and affordable ways to design the vertical alignment of HSR tracks through Palo Alto-- and it turns out that the shape of Palo Alto can tell us a lot about what those are.

Working from Caltrain track survey data, here is the shape of Palo Alto, with the vertical scale greatly exaggerated: (click to expand)

 Note a few salient features:
  • Palo Alto isn't as flat as you might think. Who knew that the University Ave station is nearly 40 feet higher than the California Ave station?
  • There are only four grade crossings in all of Palo Alto
  • Including overpasses, underpasses and grade crossings, there are only nine places where pedestrians and bikes may cross the tracks in all of Palo Alto, and only seven places where roads cross the tracks
  • The entire southern half of Palo Alto has only two places where pedestrians can cross the tracks, and both of them are very busy intersections.
  • Four creeks cross under the tracks
As we consider various grade separation options, keep this in mind: while grade separations are a sine qua non condition for high speed rail, they could also become necessary in other non-HSR scenarios for the peninsula. For example, if Caltrain traffic increased to the point that grade crossing gates blocked rush hour traffic for too long (such as if HSR were to terminate in San Jose), or if BART were to connect Millbrae to Santa Clara, as originally planned in the 1960s. Grade separated tracks are by no means a unique requirement of HSR; they are likely to be required in Palo Alto within the next few decades, HSR or not.

Constraints on Vertical Alignment

Before evaluating various vertical track profile options in Palo Alto--especially if you're going to have a charrette--it's important to lay out a few simple, fundamental design rules that govern what you can and can't make the tracks do.
  • The maximum grade (how steep the tracks can be) will be limited. High speed trains and electric commuter trains can easily climb 2% or 2.5% grades. Freight trains can't climb as steeply, and work best at 1% or maybe 1.5%.
  • The radius of vertical curves (humps and sags) is constrained by maximum train speed. The vertical curves have to be gentle, unlike a roller coaster, to keep passengers comfortable and keep the train stable on the tracks as it crests over a hill. For 125 mph (200 km/h) operation, here are some typical track design standards:

    Standard (at 125 mph)Typical RadiusMinimum Radius
    European Technical Standard of Interoperability14 km (9 mi)10 km (6 mi)
    Germany16 km (10 mi)10 km (6 mi)
    Sweden17 km (11 mi)10 km (6 mi)

    Some standards do allow vertical curves with a radius barely over 6 km (4 mi), but only in exceptional circumstances. For the peninsula, using the minimum value of 10 km is probably a good starting point. This radius results in a vertical acceleration of 0.3 m/s2, or about 1/3 to 1/4 of the acceleration you might feel in a typical elevator--infinitely smoother than a roller coaster!
  • To the extent possible, the vertical profile should avoid obstacles like creeks or existing overpasses and underpasses. While earthworks and concrete can be used to solve any such puzzle, the cost may be prohibitive.
  • Where roads cross under the tracks, the vertical distance between the road surface and the top of the rails must be 20 feet to clear trucks and buses.
  • Where tracks cross under roads, the vertical distance between the road surface and the top of the rails must be 30 feet to clear freight trains and overhead electrification.
The chart at right shows vertical track profiles for various combinations of these parameters. On the top half of the chart is a 20-foot elevated grade separation, with representative 1% or 2% grades and 10 km or 16 km vertical curve radius. On the bottom half is a 30-foot depressed grade separation (trench), with the same variations of grade and vertical curve radius. The chart gives you an idea of how long these structures need to be, based on how high (or deep) they are.

The Elevated Scenario

Elevating the tracks over Palo Alto's few remaining grade crossings is one scenario being proposed by the California High Speed Rail Authority, and is likely the cheapest.

Taking a step back: the only reason to elevate track that isn't already elevated is to lift the track over a road or pedestrian underpass, also known as a grade separation. The only place where that might happen is in the vicinity of grade crossings. Elevating the track anywhere else would serve no purpose and is not being contemplated.

Here's what the elevated scenario might look like:

  • All vertical curve radii are 10 km (6 miles)
  • At Charleston and Meadow, the tracks are raised by 7 feet and the road sunk by 13 feet. This embankment height was given in the CHSRA's program EIR/EIS maps.
  • At Churchill, the tracks are raised by 15 feet, with 1.5% ramps. The CHSRA's program EIR/EIS maps showed the embankment starting well north of Palo Alto high school, presumably to avoid dipping down and back up; however, there is absolutely no harm in the hilly profile shown here. The only people who might dislike it are freight train operators, not HSR, because of slack action. Speaking of freight trains, this embankment could be made even shorter and steeper if it didn't have to be designed with the gentle grades required for freight trains.
  • Alma (a.k.a. Palo Alto Ave) is lowered to cross under the existing track level.
  • As evident in the diagram, any claims of a continuous 20-foot wall bisecting Palo Alto from one end to the other are exaggerated.
The Depressed Scenario

With respect to the outcry over the community impact of raised embankments, it's worth looking at another scenario... and it doesn't involve tunnels! While tunnels are often contemplated as the only possible alternative to embankments, it is possible to grade separate the Palo Alto crossings by depressing the tracks into trenches. Trenches are preferable to tunnels because they can be narrower and involve far less earth moving and concrete works... although still far more work than embankments.

Here is what the depressed scenario might look like:

  • Note the length of the grade separations increases considerably, since they must dive a full 30 feet under street level and do so with gentle, train-friendly grades. The excavation itself would be even deeper, since the red curve is drawn at the top-of-rail level. Do note that accommodation of freight trains requires an extra 3 feet of vertical clearance.
  • The trenches are shown with 1.5% ramps. Shallower ramps are not possible, since the natural grade is already nearly 1% near the Churchill crossing. Steeper ramps (2% or 2.5%) would be possible if it weren't for those freight trains. (Do we see a pattern yet with those pesky freight trains?)
  • At Churchill, the northern ramp would not clear the existing Embarcadero grade separation. This complication might be solved by locally depressing Alma to match the track level, and rebuilding Embarcadero as a low overpass rather than an underpass--but as always, the devil is in the details.
  • At Charleston and Meadow, the trench would encompass the existing location of the Barron and Adobe creeks. Grade-separating the creeks is possible, but it involves lots of concrete, pumps, and ongoing maintenance expenses.
While the depressed trench scenario introduces several challenges, they pale in comparison (and cost) compared to building a full-fledged tunnel.

The Big Picture

Despite the recent controversy in Palo Alto, the city is not even close to being the most difficult to build high speed rail. There are far more challenging puzzles up and down the peninsula, for example downtown San Mateo. Many of the same design principles apply to any location on the peninsula, and as time allows we'll start discussing some more of these puzzles. As for Palo Alto, the squeaky wheel gets the blog grease!

07 May 2009

Lawsuit Preview

On August 8th, 2008, the cities of Atherton, Menlo Park, and a number of environmental and transit advocacy groups filed a lawsuit seeking to overturn the CHSRA's July 9th 2008 certification of their Bay Area to Central Valley program EIR/EIS, for failing to properly meet the requirements of CEQA environmental review regulations. This lawsuit, often characterized as an act of peninsula NIMBYism, will be heard later this month in Sacramento Superior Court.

10 interesting factoids about the lawsuit:
  1. You can read all the legal briefs on the Sacramento Superior Court's document server. Select 2008 (the year the lawsuit was filed), and enter the case number 80000022, then hit the search button. This will dredge up all the latest documents; the original complaint is at the bottom of the list and is a must-read. The complaint outlines the basic claims made against the CHSRA's environmental review process, and describes the organizations who filed the lawsuit.

  2. The lawsuit does not seek to stop the HSR project. It broadly challenges the thoroughness of the Environmental Impact Report, and specifically the selection of the Pacheco pass alignment over the Altamont Pass alignment, which was the subject of nearly a decade of contentious debate.

  3. If the plaintiffs win and the EIR certification is overturned, the CHSRA would be required to re-open and amend their program EIR to address the deficiencies, and make a new alignment decision on the basis of the amended EIR before proceeding further.

  4. A new EIR decision could very well re-affirm the Pacheco Pass alignment. It would not necessarily result in the selection of Altamont Pass.

  5. The plaintiffs include grassroots transportation and rail advocacy groups who are strongly in favor of HSR, including TRANSDEF, Bay Rail Alliance, and the California Rail Foundation. This fact alone should explode the NIMBY stereotype that is often associated with this lawsuit. They want HSR but they want it done right, and their strong and united stance is noteworthy.

  6. While the town of Atherton has a clear motive to keep HSR entirely outside its boundaries, it's not so cut and dried for co-plaintiff Menlo Park. Under an Altamont scenario, the HSR tracks would still traverse the city, but through some less affluent neighborhoods of east Menlo Park.

  7. The city of Menlo Park's standing as a plaintiff was gravely undermined when it was ruled last March 27th that they did not properly submit their comments on the EIR. In an embarrassing breakdown of basic process, no records were kept of the city's submission of comments to the CHSRA, whether by fax or U.S. mail, and the CHSRA claimed never to have received them.

  8. The Palo Alto city council emphatically and unanimously supported HSR until Proposition 1A passed in November. After severe backlash against the project in Palo Alto as details of the project became better known, the city council reversed itself and voted to join support the lawsuit. While it was too late to become a plaintiff, the city filed an amicus curiae brief on May 1st, which is now available on the court's document server (see item 1).

  9. Any response from the CHSRA to Palo Alto's brief is required to be made by May 15th. UPDATE 5/18: the CHSRA's response to Palo Alto's amicus curiae brief is now available on the court's document server (see item 1).

  10. The lawsuit is scheduled to be heard and likely decided by Sacramento Superior Court Judge Michael P. Kenny on May 29th.
Whatever the outcome, it should be interesting to watch. Make sure to have a plentiful stock of popcorn.