Urban development and CA High Speed Rail -> further cuts to I-280 San Francisco?

[sparker]

And it looks like 280 will stay in place for the long-term, as a completely different plan for rerouting CalTrain in the area was approved in April:

https://www.sfchronicle.com/news/article/New-simpler-plan-for-SF-s-downtown-rail-12855669.php

Very interesting phrasing here from the paper:

Retaining I-280 and its two ramps to Sixth Street and King Street should make it easier to sell the project to residents and commuters who feared that the plan to demolish the freeway and replace it with an Octavia Boulevard-like street would lead to gridlock.

...

"This is really about: "˜How do we get trains to the Transbay Transit Center?'"  he [Adam Van De Water of the Office of Economic and Workforce Development] said. "But we kept hearing from the neighborhood: "˜Are you going to take the freeway down?'"

And.............thousands of San Francisco Giants fans, who take 280 to the Pac Bell field, are thankful; much of the stadium's parking provisions are worked around the freeway's northeast terminus south of the Caltrain depot.  Also thankful:  folks who need to get to the Embarcadero for one reason or another (myself: Pier 23 jazz!). 

[Plutonic Panda]

Excellent! Now find a way to upgrade the 101 to a freeway through town whether that be demolishing buildings or building a tunnel. I know it isn't going to happen, but I have to say it.

[jakeroot]

Excellent! Now find a way to upgrade the 101 to a freeway through town whether that be demolishing buildings or building a tunnel. I know it isn't going to happen, but I have to say it.

Importantly, it won't happen because no one wants it.

[Plutonic Panda]

Excellent! Now find a way to upgrade the 101 to a freeway through town whether that be demolishing buildings or building a tunnel. I know it isn't going to happen, but I have to say it.

Importantly, it won't happen because no one wants it.

So the likely hundreds of thousands of people a day that would use it wouldn't want it? That's funny.

Anyways, I won't get into this topic any deeper. I meant that as more tongue in cheek. As much as I want it to happen, what's really important to understand and obvious is that it will be built when the purple line is extended to Catalina Island and the Beverly Hills Freeway is built and extended onto artificial islands alongside Malibu to connect with Oxnard. I'll stop now.

[Henry]

After what was done to the Central and Embarcadero Freeways, I am genuinely surprised that the stub end of I-280 will not suffer the same fate.

[sparker]

After what was done to the Central and Embarcadero Freeways, I am genuinely surprised that the stub end of I-280 will not suffer the same fate.

Certain S.F. political figures tried just that tactic -- but unlike the others, which were damaged beyond repair in 1989, there's enough utility for the 280 stub (the aforementioned stadium and access to the Embarcadero; the fact that the S.F. industrial district straddles 280) to continue to exist regardless of the fact that it doesn't connect directly to another freeway at its north end.  It's S.F. -- so no doubt sometime off in the future someone else will prattle on about tearing it down for "community cohesiveness" or some other rationale -- but it's been truncated briefly once -- and that's about all that will be done in that regard for the near term.

[Techknow]

Excellent! Now find a way to upgrade the 101 to a freeway through town whether that be demolishing buildings or building a tunnel. I know it isn't going to happen, but I have to say it.

Importantly, it won't happen because no one wants it.

So the likely hundreds of thousands of people a day that would use it wouldn't want it? That's funny.

What is happening with US 101 is the Van Ness BRT project, which is supposed to finish in a year or so, assuming NIMBY folks don't have their way too much.

The surface street will undergo changes, one of which I am happy about even though I don't drive there - left turns are being eliminated (except for Lombard and Broadway). It's about time - Sunset Blvd and 19th Avenue (CA-1) already don't allow left turns for the last few years. Also the traffic lights will be optimized. Just general quality of life changes but I'll take em!

[jakeroot]

So the likely hundreds of thousands of people a day that would use it wouldn't want it? That's funny.

There's no one using it right now, because it doesn't exist. San Francisco's policy, whether written or otherwise, is to stop more cars from joining the already-abysmal mess. A new freeway does not meet that goal. Consider how many of those thousands were former residents of the freeway's ROW.

I understand you may or may not have been speaking tongue in cheek, but many others have suggested this extension before, and I'm not sure why since it doesn't make any sense these days.

[TheStranger]

After what was done to the Central and Embarcadero Freeways, I am genuinely surprised that the stub end of I-280 will not suffer the same fate.

Certain S.F. political figures tried just that tactic -- but unlike the others, which were damaged beyond repair in 1989, there's enough utility for the 280 stub (the aforementioned stadium and access to the Embarcadero; the fact that the S.F. industrial district straddles 280) to continue to exist regardless of the fact that it doesn't connect directly to another freeway at its north end.  It's S.F. -- so no doubt sometime off in the future someone else will prattle on about tearing it down for "community cohesiveness" or some other rationale -- but it's been truncated briefly once -- and that's about all that will be done in that regard for the near term.

I think the article I posted showed that former mayor Art Agnos, whose legacy is primarily the removal of the Embarcadero Freeway's entire route, was against the 280 removal.   It's interesting that what he was against now (the late Mayor Lee suggesting clearing freeway ROW for future market-rate development) is exactly what he supported all the way when 480 was taken out ca. 1990-1991.  One could argue he simply favored whatever the locals in each time period were clamoring for - though as noted in previous threads, Chinatown opposition to the Embarcadero demolition was very real.

I understand you may or may not have been speaking tongue in cheek, but many others have suggested this extension before, and I'm not sure why since it doesn't make any sense these days.

Sense is a relative thing: SF's post-1950s policy has always been to encourage mass transit usage by making it difficult for car-friendly traffic improvements to occur at all, and I can acknowledge that, but decongesting city streets that are instead being used as highway corridors isn't an illogical position, just one that is not in step with much of San Francisco's philosophical leanings.  (Halfway across the world, the reverse happened in Metro Manila: light rail lines were built in the 1980s and 1990s first, before the region finally wholeheartedly accepted a through-town Metro Manila Skyway extension due to how untenable regular 2-hour traffic jams on a 9-mile boulevard have become).  And the level of mass transit needed to fully supplant car usage in SF IMO has never existed, partially because of the 1950s streetcar line removals - especially the B Geary MUNI route - and because of BART's 1960s ambitions never fully being reached once that project became more expensive a decade later.

The surface street will undergo changes, one of which I am happy about even though I don't drive there - left turns are being eliminated (except for Lombard and Broadway). It's about time - Sunset Blvd and 19th Avenue (CA-1) already don't allow left turns for the last few years. Also the traffic lights will be optimized. Just general quality of life changes but I'll take em!

IIRC I've read threads either on this forum or elsewhere about how Fell and Oak Streets used to be optimized years ago for 40 MPH traffic between Golden Gate Park and the Central Freeway (I've seen somewhere a post about the old Mabuhay Gardens nightclub/performance venue near Broadway being reachable from the Haight in 10 minutes using Oak Street, 101/Central Freeway, 80, and 480).  Will this be setup in such a way that one can run into only one or two red lights going north or south on Van Ness between Mission and Lombard?  Franklin nearby seems like it is already optimized for northbound traffic.

[sparker]

Back pre-'89 when the Central Freeway was still intact, most traffic coming off the freeway heading toward the Golden Gate Bridge simply segued north onto Franklin rather than taking Fell east to Van Ness (the route signed as US 101) all the way to Lombard; if you hit the signals right, you could almost do it in nonstop fashion (the light at Broadway would invariably get you!).  Inversely, Gough street, one-way southbound a block to the west, was used as a cutoff for the inverse traffic movement.  All that can still be done from Octavia, but with some convoluted movements that require some counterintuitive movements across traffic flow; most traffic heading north to Marin and beyond tends to simply follow the signed 101 onto Van Ness these days (it certainly seems more congested than in the '80's!).   

[Bobby5280]

San Francisco's policy, whether written or otherwise, is to stop more cars from joining the already-abysmal mess. A new freeway does not meet that goal. Consider how many of those thousands were former residents of the freeway's ROW.

At some point the Bay Area will achieve the unwritten goal of fewer cars on the streets and freeways if they just keep doing what they're doing by escalating the cost of living to ever new levels of excruciating absurdity. They have a bubble going on that's just primed to pop. I know they're not going to pay people working service industry jobs like flipping burgers within San Francisco city limits $50 per hour. But that's where they're headed. And that ridiculous, hypothetical $50 per hour rate is just for the workers to live within a reasonable commuting distance. There's news articles about software engineers for firms like Google having a hard time making ends meet on a $200,000 annual salary.

The Bay Area is getting well into an economically unsustainable situation. It's a nice fantasy to imagine a big city populated with only top one percent earners. Unfortunately that idea doesn't wash since cities can't function without their mid-level and grunt-level workers. The Bay Area isn't the only place getting ate up with development catering only to the top 10% or top 1% of income classes. At some point the people who can manage to move (or escape) to less costly locations will do so. The others who are stuck in the extreme cost zones will cut back on all sorts of buying choices, which includes having children. If these cost of living prices keep rising you'll see a lot fewer American born children in the local school systems within just a few years. Japan is already a case study on this kind of population decline.

[vdeane]

As long as the decision makers continue to believe that these things are caused by people desiring different lifestyles rather than realizing that it's all they can actually afford, nothing will change.

[jakeroot]

San Francisco's policy, whether written or otherwise, is to stop more cars from joining the already-abysmal mess. A new freeway does not meet that goal. Consider how many of those thousands were former residents of the freeway's ROW.

At some point the Bay Area will achieve the unwritten goal of fewer cars on the streets and freeways if they just keep doing what they're doing by escalating the cost of living to ever new levels of excruciating absurdity. They have a bubble going on that's just primed to pop. I know they're not going to pay people working service industry jobs like flipping burgers within San Francisco city limits $50 per hour. But that's where they're headed. And that ridiculous, hypothetical $50 per hour rate is just for the workers to live within a reasonable commuting distance. There's news articles about software engineers for firms like Google having a hard time making ends meet on a $200,000 annual salary.

The Bay Area is getting well into an economically unsustainable situation. It's a nice fantasy to imagine a big city populated with only top one percent earners. Unfortunately that idea doesn't wash since cities can't function without their mid-level and grunt-level workers. The Bay Area isn't the only place getting ate up with development catering only to the top 10% or top 1% of income classes. At some point the people who can manage to move (or escape) to less costly locations will do so. The others who are stuck in the extreme cost zones will cut back on all sorts of buying choices, which includes having children. If these cost of living prices keep rising you'll see a lot fewer American born children in the local school systems within just a few years. Japan is already a case study on this kind of population decline.

Ok.

I know the Bay Area is unaffordable to say the least, but would an extension to the 101 help that? All it would do is reduce the amount of housing in San Francisco proper. The key to reducing housing costs is building more residential units, which IMO the Bay area has not done enough of (building up at least). Sprawl and freeways don't work well in San Francisco due to geography, so the best option is a robust transit network and high density. They're working on both, but in the mean time, demand for housing has skyrocketed. Things will improve in time, but not because of new freeways.

[TheStranger]

The key to reducing housing costs is building more residential units, which IMO the Bay area has not done enough of (building up at least). Sprawl and freeways don't work well in San Francisco due to geography, so the best option is a robust transit network and high density. They're working on both, but in the mean time, demand for housing has skyrocketed. Things will improve in time, but not because of new freeways.

Mission Bay/South Beach, the Mission District, SOMA and...Hunter's Point!!!...are places I know that have had extensive new-housing construction in the last few years, mostly of the condo variety, and mostly market-rate.

Having said that...

- of the transit projects currently in play, the one that has the most potential impact for riders (BRT on Geary) is years away.  38 line has been the busiest in the wake of the 1950s removal of streetcars along the Geary corridor - a street that once had 4 streetcar lines running on it at once (A, B, C, and D).  I've read that the Central Subway project has been projected not to have as much of an impact on overall ridership patterns in comparison to anything done along Geary.

- West of the downtown core, densities remain low, particularly in the Outside Lands districts of the Sunset and Richmond, where few buildings above 2 stories even exist and very little infill is left.  There's plenty of land in those areas relative to the rest of the city, but most of the housing is still in the 1920s-1930s streetcar suburb style and the area is more prone to cooler weather than trendier districts like the Dogpatch and Mission.

- in the Dogpatch, it seems like non-residential development is booming much faster than any new housing in the 3rd Street corridor, in particular the Warriors' new arena and the UCSF hospital. 

From the 1970s to the creation of the Muni Metro T line, transit within SF seemed to be in complete stasis (the historic streetcars serve as a doubling up of existing Market Street and Financial District transit coverage, rather than reducing automobile usage).  Since the T line was created ca. 2003, the Transbay project has taken pretty long to materialize (CalTrain extension into Transbay - discussed and suggested for years - is only now finally occurring in concert with the discussions over 280), the Central Subway is a year away from completion, and the Van Ness BRT project in many ways seems to be the test of the concept for Muni buses overall.  Other than that...there's the talk about BART building a second tube to Oakland but that's not going to happen in the next 15-20 years at least, there's the E historic streetcar line which serves more to reduce the need of a transfer at the Ferry Building between the F and N than as consistent additional service, and that seems to be about it.

[Plutonic Panda]

Off topic, but what is the status of the BART and Muni rebuild? Were they not scheduled to rebuild the whole system?

[TheStranger]

Off topic, but what is the status of the BART and Muni rebuild? Were they not scheduled to rebuild the whole system?

BART has been getting new railcars but that is a gradual process.  I've actually seen the MUNI Metro new additions to their fleet several times already in SF, while I have yet to see new BART railcars on the SF/Peninsula side of the lines.  BART's current big ongoing projects: the expansion south to San Jose (of which Warm Springs is the newest station so far in that direction), and outer-suburb connector lines (of which the line to Antioch just recently opened).

MUNI is a multi-faceted agency though: MUNI Metro lightrail, the buses (both trolleybuses and regular ones), historic streetcars, and the cable cars which are pricier in fare and tourist-oriented.  IIRC the cable car system is due for another extensive rehab project like the 1982-1984 hiatus in service was.

MUNI's biggest current projects so far are the Central Subway (T line extension from Mission Bay through SOMA/Moscone Center area, Union Square, and finally Chinatown), the bus lanes on Van Ness which have been under ongoing construction for 2 years, the creation of the E historic streetcar line, and the aforementioned addition of new light rail rolling stock.

[Bobby5280]

I know the Bay Area is unaffordable to say the least, but would an extension to the 101 help that? All it would do is reduce the amount of housing in San Francisco proper. The key to reducing housing costs is building more residential units, which IMO the Bay area has not done enough of (building up at least). Sprawl and freeways don't work well in San Francisco due to geography, so the best option is a robust transit network and high density. They're working on both, but in the mean time, demand for housing has skyrocketed. Things will improve in time, but not because of new freeways.

I'm not suggesting the 101 freeway be extended. But I think the prime motivations behind removing parts or all of the Embarcadero Freeway is salivating real estate developers wanting to capitalize on the speculation activity taking place in cities like SF, NYC and some other bubble markets.

As for building more housing, it's going to take a wider variety of housing to bring the situation more into balance. Developers are gravitating to building anything new in the form of luxury apartments for the executive set. Then there's existing housing being snapped up by investors/speculators from all over the place (even foreign countries) to be renovated into units for high income people. That's the factor behind why mass-gentrification has taken place in New York City. Housing affordable to lower income workers (like kitchen help at restaurants, coffee shops, etc) isn't on the radar scopes at all.

I think if we want to just let the market do whatever it wants to do then by the same measure the developers should feel the consequences of the bust when it finally happens. They shouldn't be able to work the government and legal system to escape, fall back and re-group and then turn around to run the same scams all over again. These guys should have their nuts out there on the chopping block if they want to gamble like this. The whole thing smells like 2006 all over again.

Regarding mass transit, it's a nation-wide problem that the United States doesn't know how to build things like subway lines, light rail lines, etc without it costing an obscene fortune. And even if some new subway lines are built within San Francisco, who is going to be riding it? Typically the middle and lower income sets take mass transit. If a city is gearing its economy only for the upper class it's a waste of money building new subway lines in those zones.

[sparker]

Regarding mass transit, it's a nation-wide problem that the United States doesn't know how to build things like subway lines, light rail lines, etc without it costing an obscene fortune. And even it some new subway lines are built within San Francisco, who is going to be riding it? Typically the middle and lower income sets take mass transit. If a city is gearing its economy only for the upper class it's a waste of money building new subway lines in those zones.

The irony is that in SF, the definitively high-income areas (Pacific Heights, Nob Hill, the eastern slope of North Beach, among others) are all situated atop hills; attempting to build below-ground transit that follows the contours -- or alternately, use hundreds of feet of vertical elevators serving low-altitude stations -- would be one of the more expensive transit activities ever taken -- all in the hopes of "income-equalizing" transit ridership.  The lower income areas (those not yet gentrified) seem to be located in the flatlands in the southeast corner of the city (the high-income Marina/Cow Valley area is an outlier, of course -- an exception to the altitude/income formula), historically lower income and housing cost than the remainder of the city -- but shared with the city's industrial and warehouse base.  But that area is reasonably served by light rail (in S.F., the term well-served generally doesn't apply to bus service, electric or conventional -- too many traffic issues intervene).  Also, a lot of it is muddy "fill", not particularly conducive to underground construction (applies to much of the territory south of China Basin).  There's a reason why unconventional transit (cable car, electric buses) found their way early into S.F. usage; unfortunately, what's happening across the country is also taking place there vis-à-vis the class/income divisions -- but with limited space within the city limits, the low end simply gets squeezed out.  More transit will be built -- but likely on the surface, and in the areas most amenable to such things -- i.e., the lower end of the income spectrum -- which itself is inexorably edging upward.  But S.F., particularly its governing bodies, have their share of "social democrats"; there will likely be some space reserved for denser lower-income housing; most likely arrayed in and around the southeast industrial zones.  Some activists want that type of housing located in SOMA (south of Market) near the Caltrain station and the ballpark; but even an ostensibly egalitarian city like S.F. has its limits regarding its relationship with the financially capable, so to speak (as the knights of yore learned, sometimes the dragon wins!).  So the city ends up placing higher-density cost-contained housing in areas that aren't contested by market forces above and beyond what's S.O.P. today regarding official response.  With only 49 square miles to work with, S.F.'s going to be a conundrum for some time to come! 

[Bobby5280]

It almost goes without saying San Francisco is far from the only city in the Bay Area boasting ridiculous housing prices and overall living costs. Much, if not all, of the Bay Area is dealing with the same thing. San Jose as well as the cities and suburbs flanking it are doing as much price gouging as any community in that part of California.

I've been following news about this kind of topic more in the New York City area (in part because I lived there from '86-'91). I started taking notice of what was happening in NYC due to the amazing drop in the crime rate, particularly murder.

In 1990 the 5 boroughs of NYC had a record setting number of 2245 homicides. The crack cocaine epidemic and gang violence associated with it fueled many of those numbers. 87 victims were killed in the Happy Land Social Club arson fire. The numbers from 1991 were similar: 2154, just no mass murder via arson to give the figure an extra bump. In 1990 NYC had a population of 7,322,564. If I did my math correctly the NYC murders per 100,000 per capita rate for 1990 works out to 30.65. That's pretty terrible. But to put the ratio in perspective Flint, Michigan had a 61.98 per 100,000 per capita homicide rate in 2012. Fast forward to 2017. NYC finished 2017 with 290 homicides -the lowest total since 1951. What makes the number more amazing is the population of NYC in 2017 swelled to an estimated total of 8,622,698. The 2010 Census figure was 8.175 million. So 290 homicides for a city of 8.6 million people works out to 3.36 murders per 100,000. That's well under the US national average, 5.3 per 100,000 in 2016. FYI the US set a modern era low point of 4.4 per 100,000 in 2014, less than half the modern era record of 10.2 per 100,000 set in 1980.

Note: I delved into researching that grim material to refute some of the grossly exaggerated claims made about crime in my town, Lawton, which some people stupidly nickname "Little Chicago" and try to claim it as being the most dangerous small city in America (a stat that has never been true). Lawton is freaking Disneyland compared to Chicago (especially Chicago these days considering that city's current crime rates).

Anyway, the transformation of New York City into one of the world's safest major cities was credited to policing strategies like Broken Windows, Stop and Frisk, etc. Those policies had some effect, but crime was falling in other cities where aggressive police policies were not in place -even in places like Los Angeles, where the police department was embroiled in scandal at the time. Crime rates kept falling in NYC. But no one wanted to mention the 7 ton elephant in the room: soaring living costs and gentrification.

When I lived in NYC certain neighborhoods like Bedford-Stuyvesant and Brownsville in Brooklyn, The South Bronx or Spanish Harlem in Manhattan were places anyone regardless of color needed to avoid, especially after dark. Enter at your own risk. Nearly 30 years later all those neighborhoods have very different demographics. The transformation didn't all happen honestly either. A bunch of shady land lords, speculators, etc ran scams on many long time residents to force them out so a rent-controlled property could be renovated into luxury housing for upwardly mobile hipsters. One of the easiest scams was just not depositing rent checks. Many long term residents (quite a few elderly) were used to mailing in paper checks. Property owners simply didn't cash them. A couple or so months later: eviction proceedings. The people getting evicted usually had no money or other resources to fight the matter in court.

While New York City's crime rate has reached new lows, its homeless population has exploded in size. There's a bunch of homeless people in New York who actually work full time and then (try to) live in shelters. They're making enough to survive, but not enough to escape. There's even a good amount of political NIMBY controversy over the city trying to open new shelters for working homeless.

I don't know how San Francisco measures up with New York City with this kind of complicated situation. But it seems pretty obvious there is a trend of gentrification and overall class warfare present. Even if San Francisco has a good number of "Social Democrats" involved in the city government there's only so much those people can do. New York City has had lots of its own liberal, activist politicians over the past 30 years and they haven't prevented the more sinister things taking place there from happening.

[TheStranger]

The irony is that in SF, the definitively high-income areas (Pacific Heights, Nob Hill, the eastern slope of North Beach, among others) are all situated atop hills; attempting to build below-ground transit that follows the contours -- or alternately, use hundreds of feet of vertical elevators serving low-altitude stations -- would be one of the more expensive transit activities ever taken -- all in the hopes of "income-equalizing" transit ridership.

To some degree, isn't the Central Subway project an example of a modern subterranean attempt at providing transit to a geographic area (Chinatown) defined by uneven terrain and hills?  There's been some desire for that to extend to North Beach but no real momentum for that yet IIRC.

The BART line in SF that exists today roughly follows the Southern Freeway portion of 280 between Daly City and Glen Park, and then runs along flat portions of Mission and Market Streets.  Had the SF-Marin line not been nixed in the 1960s, Geary would have been the corridor (and it does have some hills here and there between the Tenderloin and Laurel Heights); I recall that BART being planned for Geary Boulevard was one factor in the ending of streetcar service along that key street - though today's mix of buses, historic streetcar, and BART/MUNI Metro along Market Street demonstrate how useful it is to have multiple modes in the same corridor!  (For that matter, the Muni Metro J line runs parallel to the SF BART corridor and shares the Glen Park stop with it)

[Plutonic Panda]

Off topic, but what is the status of the BART and Muni rebuild? Were they not scheduled to rebuild the whole system?

BART has been getting new railcars but that is a gradual process.  I've actually seen the MUNI Metro new additions to their fleet several times already in SF, while I have yet to see new BART railcars on the SF/Peninsula side of the lines.  BART's current big ongoing projects: the expansion south to San Jose (of which Warm Springs is the newest station so far in that direction), and outer-suburb connector lines (of which the line to Antioch just recently opened).

MUNI is a multi-faceted agency though: MUNI Metro lightrail, the buses (both trolleybuses and regular ones), historic streetcars, and the cable cars which are pricier in fare and tourist-oriented.  IIRC the cable car system is due for another extensive rehab project like the 1982-1984 hiatus in service was.

MUNI's biggest current projects so far are the Central Subway (T line extension from Mission Bay through SOMA/Moscone Center area, Union Square, and finally Chinatown), the bus lanes on Van Ness which have been under ongoing construction for 2 years, the creation of the E historic streetcar line, and the aforementioned addition of new light rail rolling stock.

Thank you for the update! I could have sworn that BART was going to rebuild their existing subways or parts of it as they were deteriorating.

[sparker]

Interestingly, the only connection between the new Central Subway line and the rest of the MUNI LR/trolley network is a surface interchange at its southern end with the E-line down King Street; it crosses the Market Street complex (stacked surface trolley/Muni "J" line, BART) below the present NE/SW tunnels; obviously some connection needed to be made in order to get the trains to the service facilities. 

BART is doing "spot" rebuilds as needed (new rails, ties, upgrading the 3rd rail power buss); the line that seems to be problematic is Walnut Creek/Pittsburg; more incidents and delays on that segment than on any other.  Otherwise, they're still working on the Warm Springs-Berryessa (San Jose) extension, which is a couple of years behind schedule -- and have the downtown San Jose-Santa Clara University extension in the wings (although those plans were truncated/downgraded to a single-track facility a couple of months ago).       

[TheStranger]

Interestingly, the only connection between the new Central Subway line and the rest of the MUNI LR/trolley network is a surface interchange at its southern end with the E-line down King Street; it crosses the Market Street complex (stacked surface trolley/Muni "J" line, BART) below the present NE/SW tunnels; obviously some connection needed to be made in order to get the trains to the service facilities. 

I do know there'll be a station-passageway connection between the BART/MUNI Metro Powell Street stop along Market, and the Union Square station proposed for the Central Subway.  I suspect it'll be one of those hallway setups not unlike the station-to-station passageways between lines on the Paris Metro.

As for the SJ BART extension, how far in the future is the Berryessa-Diridon segment?

[sparker]

Interestingly, the only connection between the new Central Subway line and the rest of the MUNI LR/trolley network is a surface interchange at its southern end with the E-line down King Street; it crosses the Market Street complex (stacked surface trolley/Muni "J" line, BART) below the present NE/SW tunnels; obviously some connection needed to be made in order to get the trains to the service facilities. 

I do know there'll be a station-passageway connection between the BART/MUNI Metro Powell Street stop along Market, and the Union Square station proposed for the Central Subway.  I suspect it'll be one of those hallway setups not unlike the station-to-station passageways between lines on the Paris Metro.

As for the SJ BART extension, how far in the future is the Berryessa-Diridon segment?

That segment actually passes the Diridon station -- it'll supposedly have a series of escalators from the tunnel to reach the station itself -- and then heads northwest under Stockton Ave. (to avoid the Caltrain service facility) and then next to the Caltrain tracks, with a terminus near the present Santa Clara depot (just east of Santa Clara University).  To contain cost and keep the cut/cover work along Santa Clara Street relatively narrow, the portion south of the Berryessa station was reduced to a single-track facility (with a passing track at Diridon).  Preliminary surveys are supposed to start next spring (2019) with construction either commencing in late 2020 or early 2021, according to the Murky News.  With the delays (and commensurate rationalizations) of the Warm Springs-Berryessa segment, BART is reluctant to project a completion date at this point (since they're engaging in inner-city construction with all the potential complications that entails, I can hardly fault them for that!).  It's been an ordeal just getting it down through Milpitas to anywhere in San Jose (even with it situated on a straight-shot former WP alignment); I for one hardly expect less problems with the downtown/Santa Clara section. 

[myosh_tino]

From what I have read, the underground portion of the BART line isn't a single track but rather a single tunnel with two levels, each containing a single track.  Downtown San Jose businesses favored this type of tunnel because it eliminates the need to use the cut-and-cover method of construction.  The tunnel would be bored with minimal disruption at the surface.