Focus on: SF Transbay Transit Center

San Francisco's Transbay Transit Center, planned to be built in the years 2012-2018, will replace the decrepit Transbay Terminal and become the new transit hub of downtown San Francisco. The TTC includes a new underground rail station, which Caltrain and HSR will use as their northern terminus. The station will be connected to the tracks that currently terminate at 4th & King by a new downtown tunnel extension, also known as the DTX.

The DTX and revamped Transbay Terminal were planned since long before the high speed rail project, to better connect Caltrain and the peninsula to San Francisco and the east bay. Long starved of funds, the project was finally approved by San Francisco voters in 1999, with the creation of a new Transbay Joint Powers Authority (TJPA) charged with designing, building, operating and maintaining the DTX and the new Transbay Transit Center.

Fast-forward a decade, and Caltrain is playing second fiddle to the California High Speed Rail Authority, which (despite some past theatrics) fancies the Transbay Transit Center and its all-important underground train box as a northern terminus and veritable Grand Central of the West. Officials from the respective agencies are now squabbling over the design of the rail station, with the CHSRA's chairman Quentin Kopp calling the TJPA's design inadequate. (As it turns out, he may be right!) The disarray threatens the project's prospects for receiving economic stimulus funds, which has California politicians in Washington increasingly concerned that the appearance of "shovel readiness" is eluding their grasp.

The TJPA and CHSRA have developed a memorandum of understanding to govern future collaboration on the design of the DTX and Transbay Transit Center--not a moment too soon, since the TJPA plans to award construction contracts for Phase 1 of the project (possibly including the $390 million train box) starting in October 2009.

In this post, we'll discuss the rail component of the Transbay Transit Center and the DTX tunnel. We'll begin with a summary of the current train station design, as presented at the TJPA's March 12th board meeting (the source of most of the illustrations in this post), followed by some thoughts on what makes a good train station, and conclude with a discussion of shortcomings in the current TJPA design.

2013 Update: since this post was written in early 2009, the design of the TTC has evolved in small ways.  These are discussed in a 2010 update and 2012 update.

Many thanks to Richard Mlynarik for his advice and enlightening discussion of these issues.

Current Train Station Design

A cross section of the TJPA's design for the Transbay Transit Center (as of late 2008) is shown at right. It is a long, narrow building that occupies approximately the same footprint as the Transbay Terminal and its ramps (see location map).

The underground train station is reached via a tunnel which starts a bit before the existing Caltrain terminal at 4th and King Streets. After a ramp down and a sharp right turn onto Townsend Street, the tunnel takes a sharp left onto 2nd Street, then a sharp right into the terminal building.

Station Layout. The Transbay rail station has two levels: a mezzanine level (immediately below grade) and a second basement level with platforms and tracks, as shown in the plan at right by TTC architects Pelli Clarke Pelli. The mezzanine level does not extend for the entire length of the station; the south end contains a Greyhound bus terminal, and a large portion is reserved for 'program space'. What remains of the mezzanine level is further subdivided: a central area concentrates passenger access and contains ticketing facilities and some retail shopping, and is flanked by a Caltrain waiting area on one side and a larger HSR waiting area on the other side, which will likely feature airline-like passenger security screening.

Track Configuration. The station has six tracks, tentatively numbered 21 through 26, from south to north. The two southernmost tracks (furthest from downtown) are dedicated to Caltrain. The remaining four tracks are dedicated to HSR. Due to differing platform height and passenger security requirements, the tracks are permanently assigned to Caltrain or HSR and cannot be switched. Adjacent tracks are placed on 16 ft 6 in (5 m) centers. Two tail tracks were originally planned to extend beyond the end of the terminal; their layout has changed several times, but they are now "deferred until operationally required." Of the many tail-track options evaluated (including a loop tunnel back to 4th & King), one configuration required the southern track to pinch inwards to avoid building foundations, cutting the Caltrain platform short. The only vestige of the tail tracks is a bulge in the end of the train box, with knock-down panels where a future tail track tunnel might be built, if they ever turn out to be "operationally required."

Platforms. The station is planned with three island platforms flanked by a track on each side, 1300 ft (400 m) long and 30 ft (10 m) wide, curving sharply at the entrance to the station. The curvature (500 ft or 150 m radius) opens gaps in excess of one foot (0.3 m) between the platform edge and train doors. The platform height is 3 ft 6 in (1067 mm) for the level-boarding HSR tracks, and 2 ft 1 in (639 mm) for Caltrain-- the latter value seemingly picked to match the floor height of a Bombardier car. A row of columns supporting the terminal building above runs along the length each platform, spaced on 42 ft 6 in (13 m) centers. The assumed HSR schedule turn-back time is 30 minutes, with a nominal platform dwell of 20 minutes, giving the four HSR tracks a total throughput of 6 high-speed trains per hour (after accounting for the delay required for another train to re-occupy the platform). The Caltrain schedule turn-back time is 20 minutes (nominal dwell of 18 minutes), giving the two Caltrain tracks a throughput of about 4 trains per hour (or 6 tph with tail tracks). The TJPA claims it can accommodate Caltrain's planned TTC ridership of 31,700 passengers per day (versus ~8000 per day at 4th & King today).

DTX Tunnel. The downtown extension tunnel is designed with three tracks. The portions of the tunnel close to grade level are built using cut-and-cover methods, with the middle portion mined under Rincon Hill, until Folsom St. (curved section shown in TJPA drawing at right). The tunnel includes a new underground Caltrain station along Townsend St. between 4th and 5th, adjacent to the existing 4th & King Caltrain terminal. This station has two short 800-ft (240 m) outside platforms, with the center track used for overtaking trains stopped at the station. Since rolling stock choices for Caltrain and HSR are yet to be determined, the engineering drawings show clearances sized for Bombardier cars. Like the TTC, the new 4th & Townsend station features a mezzanine level above the tracks, requiring the entire alignment to be built at sufficient depth to allow for the requisite clearances.

4th & King Station. The DTX project preserves the existing 4th & King station location as a Caltrain terminal and train storage yard, since the TTC's two platform tracks will not support Caltrain's anticipated service levels or allow diesel trains (diesels may be used for Dumbarton service). Caltrain is planning for eight platform tracks at 4th & King. Their Caltrain 2025 plan, Appendix D, issued before Caltrain was assigned just two platforms at the TTC, assumes that fully 60% of Caltrain services will terminate at 4th & King. None of the platforms at 4th & King will accommodate HSR, due to the difference in platform height.

Curve Radius. The 1.4-mile DTX features three extremely sharp curves that allow the tracks to conform as best they can to the San Francisco street grid. The minimum curve radius is just 500 feet (150 m), the sharpest allowable radius for European off-the-shelf trains, and too sharp for some Japanese high speed trains. In theory, such curves can be navigated at a maximum safe speed of 35 mph (55 km/h); in practice, slower speeds of 25 to 30 mph are likely. Regardless of the exact speed, such tight curves will elicit deafening screeches from the stiff, long-wheelbase bogies that are a technical necessity for high speed rail. The DTX is likely to set California-wide technical requirements for high speed trains.

Station Throat. The track schematic above shows the configuration of the tunnel and underground station tracks, with the new underground Mission Bay station (under Townsend St.) also featured. The throat of the station, where the three tracks of the DTX tunnel divide into the six platform tracks of the TTC, begins all the way back at Bryant St., about 3800 ft (1150 m) before the bumpers at the end of the station platforms. At 25 mph, a train takes nearly two minutes to snake its way through the throat of the station. Most of the track switches are according to US freight (i.e. Caltrain) standards, AREMA #14's.

Passenger Access. The TJPA is sizing the station for simultaneous peak passenger flows of 5000 pax/hour for Caltrain and 4000 pax/hr for HSR. All vertical access (escalators and stairs) is oriented lengthwise along the station axis. Rather than accessing platforms directly from the street, passengers are funneled through a grand entrance and waiting areas in the mezzanine level. After accessing the platforms, passengers must walk some distance along the quarter-mile platform to their correct boarding location.

Grade Separations. Between the existing Tunnel #1 and the entrance to the new DTX tunnel, the Caltrain tracks cross 16th St. and Common St at grade. After the latter grade crossing, the tracks descend underground via a 1960 ft (600 m) open cut. A later grade separation of these streets would require demolishing this U-shaped open cut ramp and extending the DTX tunnel.

So What Makes a Good Train Station, Anyway?

Designing a train station for efficient operations is not rocket science, although space constraints can considerably complicate the exercise. The extremely constrained location of the TTC, combined with the very high level of train traffic envisioned by 2030, demand an intelligent station design.

We can draw up a simple list of three key requirements for a good terminal station design:

1. High train throughput. By definition, all trains arriving at a terminus must reverse direction. The station must be able to turn back trains at the highest possible rate; otherwise, the station itself becomes a worse bottleneck than the tracks leading to it.
   
2. High passenger throughput. The flows of passengers into and out of trains must be made as simple and direct as possible. This involves an optimization of street access, ticketing facilities, and vertical access to station platforms. Limited and circuitous passenger throughput can become a bottleneck at peak hours.
   
3. Operational flexibility. The station must provide flexibility to adjust service patterns in response to real-time conditions. It must degrade gracefully in the event of a service disruption, minimizing the possibility of cascading delays.

As we re-examine the TTC design, keep these three requirements in mind.

Shortcomings of the TJPA Rail Design

Throat Cancer. The TJPA station throat design is a bottleneck that promises low speeds, long traversals and frequent conflicts (when a key piece of track is occupied by one train, preventing other trains from passing.) The train throughput of a station throat, which sets a limit on the throughput of the station itself, is related to its overall length (shorter is better), train speeds (higher is better) and most importantly, topology (track switches thoughtfully laid out to allow conflict-free parallel moves.) The station throat begins a full 3/4 mile (1150 m) from the end bumpers, causing trains to occupy the throat for far longer than necessary and increasing the delay required for a platform to be re-occupied by the next arriving train, thus limiting train throughput. The station throat does not allow simultaneous arrivals and departures from most platforms (such conflict-free parallel moves are the holy grail of throat design because they minimize the re-occupancy delay), severely limiting train throughput and operational flexibility.

Different Platform Heights. With Caltrain's fleet due for a complete replacement with the advent of electrification, and with Caltrain's platforms due for complete reconstruction with the track expansion for HSR, the opportunity exists to make HSR and Caltrain share the same standard platform height. (The shared use of the same platform by HSR and commuter trains is common practice in Europe.) Designing the two systems for different platform heights makes this already-constrained station design even less operationally flexible because platform tracks cannot be assigned as needed to (a) minimize conflicts in the station throat, (b) accommodate service peaks, and (c) recover from disruptions. While this isn't TJPA's decision to make, the TJPA, CHSRA and Caltrain should agree on a single existing standard that is based neither on California's outdated safety clearance regulations, which were written for freight trains in 1948, nor on the floor height of Bombardier cars. Inventing new platform standards will hinder the ability of both operators to procure trains off-the-shelf and will create an operational mess.

Mis-Oriented Passenger Flows. The dominant pedestrian flows, especially for Caltrain, come from the center of San Francisco, which lies along the flank of the station (unlike traditional European terminals, which are often oriented toward the city center). Vertical access to the station platforms should be oriented perpendicular to the station, towards Market Street, to make use of the inherent horizontal reach of stairs and escalators to bring passengers closer to their destinations. Funneling all passengers through a grand entrance, concourse, fare gate, etc., all along the skinny axis of the building, while perhaps architecturally spectacular, does nothing for passenger throughput. Caltrain monthly pass holders need to get from the street to the platform, pronto, without any scenic detours.
Homeland Security Theater. The total segregation of passenger flows for HSR and Caltrain, to accommodate airline-style HSR security screening, constricts passenger throughput and prevents the flexible re-allocation of tracks. As the Madrid train bombings of 2004 demonstrated, securing HSR facilities does nothing to prevent mass carnage on the rails. Securing HSR without securing Caltrain is no more effective than building a moat only halfway around a castle. If security theater cannot be avoided, then adopt a security plan that does not operate the TTC as two separate mini-stations. With only two available tracks, Caltrain would find itself just one minor breakdown away from a total disintegration of their rush hour schedule, a disaster for operational flexibility.

Extremely Tight Curves. While curve radii at the location of the TTC itself are dictated by the street grid and surrounding building foundations, the two curves in the DTX tunnel approach (to turn from 7th onto Townsend and from Townsend onto 2nd) are much sharper than they need to be, and beyond the capability of some off-the-shelf high speed trains. High speed trains aren't MUNI street cars and won't turn on a dime; they are longitudinally stiff to provide good stability at high speeds. At these two curves on the 1.5-mile approach to the station, the radius could be easily increased from 150 m to at least 200 m, saving 30 to 40 valuable seconds in the long, slow crawl into the TTC, and increasing the train throughput of the station throat. If the throat can be straightened as well, a 200 m minimum radius would allow off-the-shelf procurement of trains without the need for expensive modifications to fit the extreme curves of the DTX, which threaten to set a standard for the entire California high speed rail system.

Odd Tail Track Arrangement. Among the various design options considered before trail tracks were de-scoped, no clear function can be ascribed to the tail tracks under Main Street. They could theoretically have been used to increase HSR train throughput by (a) performing cleaning and resupply of trains without tying up a platform and (b) switching departing trains to the northern platform, to minimize conflicting moves in the station throat during departure. In practice, none of the TJPA's attempted tail track layouts exploited these possibilities; they amounted to very expensive train parking.
Inefficient 4th & Townsend Layout. The new underground station at 4th & Townsend should have four tracks to allow overtaking stopped trains in both directions (to improve train throughput) and its platforms should be lengthened to 400 m to allow HSR trains to use them in the event of a disruption at the TTC, thus improving operational flexibility to HSR and Caltrain's benefit.

Oversized DTX Tunnel. Despite the high level of train traffic, a simple two-track tunnel into the station would do just fine. Because trains are limited to the same homogeneous speed by the sharp curves, a two-track tunnel could easily support 15 to 20 trains per hour, each way, or far more than the terminal could feasibly handle. The third track makes the tunnel needlessly expensive, and requires fancy construction techniques like the New Austrian Tunneling Method (NATM).

Suggestions for Improvement

All of the design issues enumerated above have been analyzed by San Francisco rail advocates, who have suggested numerous possible improvements for the DTX and TTC rail station in order to exploit the constrained site as efficiently as possible for both Caltrain and HSR. These detailed suggestions will be the subject of an upcoming post.

The rail infrastructure of the Downtown Extension and Transbay Transit Center is not nearly as sexy as sweeping glass towers and roof gardens: it's invisible, and for now, it's just a box. We can only wish that the architects realize the extent to which that simple, invisible box will determine the operational efficiency of San Francisco's train station for decades to come.

Memorandum of Understanding

The California High Speed Rail Authority recently added to its website the text of a new Memorandum of Understanding (MOU) that will soon be signed with the Peninsula Corridor Joint Powers Board (PCJPB, a.k.a. Caltrain).

This document, hammered out by the two parties, establishes an "initial organizational framework" whereby the PCJPB and CHSRA become partners in the planning, design and construction of improvements to the Caltrain corridor. The CHSRA already approved it at their March 5th board meeting; approval by the Caltrain board of directors is expected at their next meeting on April 2nd.

The MOU lays out some key points of understanding:

• A new Program Director, reporting to both the Caltrain and HSR executive directors (Michael Scanlon and Carrie Pourvahidi, respectively) will coordinate and oversee the work of the staffs and engineering consultants of the two parties.
  
• Caltrain will continue to operate during HSR construction.
• The needs of Caltrain must be considered, including the ability to operate 8 trains per hour in each direction (as already set forth in the Caltrain 2025 plan).
  
• The peninsula corridor and all existing improvements belong solely to the PCJPB.
  

The MOU is also interesting for what it does not spell out:

• How and to what extent will the two organizations (governing boards & staff) be integrated?
• Who will pay for what?
• Who will be liable for what?
• Who will own what, after the project is completed?

The MOU states that all these things will be planned. As the saying goes, "the planning will continue until we find out why no decisions have been made."

Freight on the Peninsula

UPDATE (3/18) Thanks to Martha Martinez, PCJPB Secretary, for providing the full text of the 1991 trackage rights agreement that governs freight access on the peninsula.

Freight trains operate daily along nearly the entire length of the Caltrain corridor (San Jose photo at right by Michael Patrick), and make up less than 5% of train traffic on the peninsula. The freight trains move mostly at night, when Caltrain traffic is sparse.

Freight trains have always been part of the traffic mix on the peninsula. The corridor formerly belonged to freight operator Southern Pacific, which sold the 51.4-mile railroad right of way to the Peninsula Corridor Joint Powers Board (Caltrain) in 1991 for $219 million.

Existing Freight Traffic

Thanks to Kevin Hecteman for the following description of freight traffic patterns on the peninsula:

Union Pacific currently operates three freight trains per weekday, all based out of the yard next to the South San Francisco Caltrain station.

1. SOUTH CITY SWITCHER: Goes on duty early in the morning: switches industries between South City and Pier 96 in San Francisco. Shippers include Granite Rock, Central Concrete and Pacific AgriProducts in SSF; Sierra Point Lumber near the Bayshore station; Dean's Refrigerated Trucking off Carroll Avenue in SF; Darling International, a rendering plant near Pier 96; and the Waste Solutions Group dirty-dirt concession at Pier 96. Famous for being the last freight train serving San Francisco. A sizable photo archive detailing this operation can be found here.
   
   
2. BROADWAY LOCAL: Goes on duty at 5:30 p.m.; switches industries between SSF and San Jose, such as the Port of Redwood City, after the evening rush hour ends. (One such industry is the Unilever plant in Sunnyvale, as seen here.)
   
   
3. MISSION BAY HAULER: Goes on duty at 6:30 p.m.; gathers up all the outbound cars brought in by the other two locals and hauls them to the UP yard in Milpitas, then returns with the inbound cars for distribution by the locals. This train can easily see 60 to 90 cars.
   

Freight in the Peninsula's Future

All existing plans for improving the Caltrain corridor (namely, Caltrain's 2025 Plan, including electrification, as well as California high speed rail) explicitly preserve the capability to carry freight up the peninsula, and allow for a possible expansion of freight traffic.

Whether this is justified by existing traffic levels (less than 5% of train movements) is open to debate. If freight service on the peninsula were discontinued, some traffic would likely move by truck over Highway 101, and the rest of it, and associated jobs, might disappear altogether from San Francisco and the peninsula.

Regardless of actual demand, the peninsula freight operator, Southern Pacific (and its successor, Union Pacific) retained trackage rights from Caltrain when the latter acquired the tracks, giving UP the right to operate a certain quota of freight trains on the peninsula. Such agreements are administered by the Surface Transportation Board, and would likely be difficult to terminate not only because of the bureaucratic process, but because UP (no supporter of the HSR project) might attempt to use their rights as a bargaining chip against the high speed rail authority.

So, while freight accounts for only a tiny minority of train movements that is likely to become infinitesimal when Caltrain service is expanded and HSR service begins, all agencies involved are proceeding under the firm assumption that freight trains will be accommodated for all time--regardless of whether or not this makes sense from an economic or technical standpoint.

STRACNET: A Military Twist

The Department of Defense designates a nationwide network of rail links critical to national defense, known as the Strategic Railroad Corridor Network, or STRACNET.

This network provides the readiness to ship materiel from military depots to ports of embarkation in the event of a war emergency. STRACNET was established in the 1970s, when freight railroads were falling into disrepair, and sets rock-bottom minimum standards for:

• operating speed, with a minimum desired track speed of 40 mph
  
• clearance profile, to ensure that track side obstructions do not foul the DOD load clearance requirements defined in MIL-STD-1366
  
• weight capability, to allow M-1 tanks to be carried in pairs on 140-ton flat cars.
  

Why would we care about this Cold War relic? As it turns out, the peninsula corridor is part of STRACNET, or at least it was according to the 1998 update (see California map on page 30), presumably to access the mighty port of embarkation known as San Francisco--never to be outdone by its far bigger rival across the bay. The makeup of STRACNET is updated every few years by the DOD and FRA; there is no guarantee that the peninsula corridor will retain its military designation.

Because the Caltrain corridor already accommodates daily freight trains (see Caltrain's clearance standards, also drawn as a green outline in the figure at right), Caltrain more or less meets the STRACNET requirement (red outline). Its track maintenance standards exceed the operating speed and weight requirements. Beyond the loading clearances shown at right, available structural clearances are much wider than required by the DOD because Caltrain already complies with the draconian clearance requirements of the California Public Utilities Commission.

Bottom line: STRACNET is a yawner, although that is unlikely to stop HSR opponents from making an issue out of the grievous omission of STRACNET from CHSRA environmental impact documents.

Implications of Freight for Caltrain and HSR

Freight service (in addition to HSR) has a few important implications for the future of the peninsula corridor, none of which are likely to be welcomed by neighbors.

1. More Tracks. The 125 mph speed envisioned for HSR on the peninsula requires tracks to be banked in curves (see the Top 10 Worst Curves for more technical details), with the outside rail raised as much as 6 inches higher than the inside rail. This steep banking is incompatible with slow and top-heavy freight cars and can lead to derailments excessive rail wear. The CHSRA's plan for four tracks along the entire length of the peninsula is likely to be driven just as much by the perceived need to accommodate freight trains (by having one pair of tracks banked, and the other pair not) than any service pattern considerations to allow trains of differing speeds to overtake each other. The need for four tracks may be somewhat alleviated without freight trains.
   
   
2. Taller Electrical Poles. Track improvements are being designed to increase Caltrain's clearances from AAR Plate F to the much taller AAR Plate H. This would allow "excess height" freight cars such as autoracks and double stack container cars--never mind for which supposed customer on our dead-end peninsula! Expanding from the existing Plate F condition to Plate H requires another 3 feet of vertical clearance, which will force the overhead electrification of the tracks to be built at least 3 feet taller, thus increasing visual blight.
   
   
3. Higher Embankments. Freight trains are much heavier than high speed trains or the "non-compliant" EMU trains coveted by Caltrain. In fact, the very high speed trains of the type required to run at 220 mph in the Central Valley are some of the lightest trains anywhere. On the other hand, heavy weight requirements lead to beefy bridge decks, further inflated by seismic requirements. For grade separations where a road crosses under the track, every additional foot of bridge deck thickness adds an additional foot to the height of the rail embankment (or an additional foot to the depth of the underpass excavation, with attendant increase in the length of the approach ramps.)
   
   
4. More Noise. Freight trains are generally not maintained to the same high standards as high speed passenger equipment. Freight trains with diesel locomotives and wheel flat spots banging along the track will be much louder than electric trains, even after horn-blowing is obviated by grade separations. Accommodations that are now being made for freight operations may lead to an increase in noisy freight traffic.
   

From the point of view of civil engineering companies who will design and build HSR infrastructure on the peninsula, every additional cubic yard of concrete and every design complication is a potential path to extra profit. To this end, the requirements arising from Union Pacific freight service and STRACNET may indeed be quite welcome. After all, if it's profitable, why not let the tail wag the dog?

Why They Chose the Caltrain Corridor

A lot of peninsula residents now becoming aware of the California High Speed Rail Authority's plans are concerned that HSR will require extensive eminent domain takings along the Caltrain corridor, and suggest that HSR be routed instead via the existing (pre-blighted) corridors of highways 101 or 280. Those options were studied and formally eliminated in the CHSRA's Bay Area to Central Valley Final Program EIR/EIS, certified in July 2008. It's worthwhile to examine why the CHSRA chose the Caltrain corridor.

The simple answer: there's a lot more room in the Caltrain corridor than most people realize.

Right of Way Statistics

Average width: 112 ft (34 m)
Percentage 75 ft or wider: 94%
Percentage 80 ft or wider: 88%
Percentage 85 ft or wider: 80%
Percentage 90 ft or wider: 77%
Percentage 95 ft or wider: 70%
Percentage 100 ft or wider: 68%

The chart at right shows a graph of the width of the railroad right of way (in feet) versus milepost, constructed from official Caltrain right of way maps.

CHSRA documents indicate that the minimum width required for four tracks is about 75 feet; this is shown by a dotted red line in the chart. A comfortable width (allowing access roads and landscaping) is about 100 feet. The results:

• Along the two thirds (68%) of the peninsula rail corridor that are wider than 100 feet, HSR is an easy fit within the existing right of way.
• For another quarter (27%) of the corridor that is between 75 feet and 100 feet wide, HSR is a tighter fit, but possible without eminent domain
• For the remaining 5% of the corridor that is narrower than 75 feet, some eminent domain is necessary to achieve a minimum width of 75 feet.

How Much Eminent Domain?

One can calculate the area of land required to bring the entire corridor to 75 ft minimum width. Again some corridor length statistics, straight from the chart above:

50 (minimum) to 55 feet wide: 0.38 miles (needs 25 feet extra)
55 to 60 feet wide: 0.09 miles (needs 20 feet)
60 to 65 feet wide: 0.59 miles (needs 15 feet)
65 to 70 feet wide: 0.06 miles (needs 10 feet)
70 to 75 feet wide: 1.75 miles (needs 5 feet)

Adding up the series of strips with the dimensions above, the grand total amount of land required to widen the entire peninsula corridor to a minimum of 75 feet is less than four acres.

To put that figure into proper perspective:

• the entire corridor is about 700 acres, so the required land is about half a percent more.
• the CHSRA has a budget of $4.2 billion for the San Francisco to San Jose segment. At Atherton prices ($4 million per acre), the required land is worth about a third of a percent of that budget.

(Disclaimer: this analysis is based on Caltrain corridor maps, which are not official survey documents. Your mileage may vary; discrepancies of several feet have already been noted in some 100+ year old property lines. Also, temporary construction easements are not included.)

At the turn of the 20th century, the Southern Pacific secured enough land to expand the railroad to four tracks, precisely what is now envisioned for high speed rail. Is it any wonder that the California High Speed Rail Authority considers the Caltrain corridor a slam-dunk?