Why does the Bay Area have so many cloverleafs?

[SeriesE]

The parclos on I-880 in Fremont and Union City used to be full cloverleafs (obvious in satellite imagery) so it's not like nothing has been done to upgrade the interchanges.

[SectorZ]

Are you effing kidding me?  What is your malfunction with this obsession with trashing the San Francisco Bay Area?  Are things just that peachy and rosy in Massachusetts that you can't let some place your family has origins go?

This was hands down the most ridiculously defensive response I've seen on this forum. That's saying a lot.

At least our cloverleaves are poopless out in MA...

[Max Rockatansky]

Are you effing kidding me?  What is your malfunction with this obsession with trashing the San Francisco Bay Area?  Are things just that peachy and rosy in Massachusetts that you can't let some place your family has origins go?

This was hands down the most ridiculously defensive response I've seen on this forum. That's saying a lot.

At least our cloverleaves are poopless out in MA...

How is that being defensive?  Are you saying I'm defensive because I don't particularly care for some random new user from Massachusetts having a constant tone of negativity towards the a Bay Area because his Dad didn't like it?  What new ground are we exactly covering here that hasn't been discussed about a million times by now? 

And I'm I getting it right that you are implying that I'm somehow defending the current state of road based transportation in the Bay Area with the "poopless"  statement?  If that's the case of you clearly haven't read much on this board.  More so, is that a hot take on the homeless situation in the Bay Area? 

[roadfro]

Okay... Let's have more discussion about Bay Area cloverleaf interchanges and less commentary about the merits/motivations/whatever of individual users' replies... Thanks.

[michravera]

880 to 101 would be a freeway to freeway interchange.  It would also be somewhat limited in height due to the approach paths for San Jose Airport.

kkt is correct - the San Jose airport is the primary reason for the lack of an upgrade to this interchange.  You can't add ramps above the interchange due to the approach paths to the airport.  (This is also why there isn't an interchange between I-880 and CA 87.)  Also, you can't put ramps below the interchange due to the high water table in that area.  US 101 (the lower of the two freeways) has intermittent pavement flooding problems, despite Caltrans having multiple pumps to keep the roadway dry.  So, we're stuck with the cloverleaf configuration.   

It's manifestly untrue that a flyover from I-880 to US-101 wouldn't be allowed because of the approach path to SJC. In addition to do being able to do it in the existing headroom, the blast fence at the end of runways 30 is almost as high as the flyover would have to be. SJC may be a reason for not making a US-101/CASR-87 interchange, but it certainly isn't the reason that US-101/I-880 hasn't been done, attempted, started, or well studied. My guesses are any combination of the following:
1) Construction costs
2) Possible Land Acquisition cost
3) Construction impact upon existing traffic (irony of ironies)
4) Recent construction in the area
5) Urbanist opposition to helping roads in any way.

[kkt]

US 101 - CA 92 was one terrible cloverleaf that's been made much better.  Much of the work was done in the early 1980s, if I remember right.

[TheStranger]

More recently both San Jose (city) and Santa Clara (county) planners are firmly in the "urbanism" camp, and since projects within metro bounds are vetted by all agencies, not just Caltrans, priorities as well have changed -- and unless there's a specific safety issue, older interchange modifications generally are well down the "to do" list.  But this is not a specific Bay Area issue -- and while this area was among the first to manifest this sea change in priorities, it has certainly been matched elsewhere in the state, like L.A. and its virtual new-freeway ban in the L.A. basin; and definitely with Sacramento, which hasn't seen a completely new freeway facility (although CA 99 was upgraded to a full freeway north of I-5) since 1981, when I-5 was completed south of town. 

Would the Capital Southeast Corridor project count as new construction for the Sacramento region?  Though I don't think it is intended to be freeway (yet).

  But right now one long-pressing road/connectivity issue is being considered -- reconstructing the CA 262 Mission Blvd. connection between I-880 and I-680 into a full freeway to eliminate a peak-hour bottleneck in the Warm Springs area that affects local traffic as well -- a situation that has prompted renewed public interest in the concept.  We'll just have to see what transpires regarding both whether such a project gets out of the starting blocks and how timely the funding process plays out.  262 is one case where the concept of "induced demand" is a ship that sailed when the original CA 237 freeway connecting the two N-S Interstates was cancelled -- about 3 out of 4 drivers heading to I-680 and points beyond (Pleasanton, Livermore, Tracy, etc.) crowd onto 262 since it's the shortest connection between the freeways.  So far there's been no massive or even vocal pissing and moaning from the "woke" and/or urbanist sector regarding the preliminary planning/design for the freeway upgrade; we'll see what happens when a final design is completed and proffered.       

I'll actually start a separate thread for this as it is interesting in of itself for many historic and current reasons! 

[TheStranger]

US 101 - CA 92 was one terrible cloverleaf that's been made much better.  Much of the work was done in the early 1980s, if I remember right.

Looking at HistoricAerials, the work to upgrade that interchange to add the two flyovers (SB 101 to EB 92, NB 101 to WB 92) occurred sometime between 1984 and 1988.  There are stubs for flyovers that were never built (EB 92 to NB 101 and WB 92 to SB 101) during that project.

[ztonyg]

US 101 - CA 92 was one terrible cloverleaf that's been made much better.  Much of the work was done in the early 1980s, if I remember right.

A more recent elimination of a cloverleaf was CA 92 and CA 82. It's now a rather nice parclo.

[jdbx]

The cloverleaf at I-680 / CA-4 is another example of an awful interchange that has had few improvements.  Back in the early 2000's, around the same time as the HOV lanes were added to that stretch of I-680 they moved the I-680 merge lanes onto a set of parallel C/D lanes, but otherwise it's nearly the same as it was when built back in the 1960's.  Improvements have been planned for this interchange for a good 20 years now, but funding has not been made available yet.  The weaving situation on CA-4 is made even worse by the short spacing of the adjacent Pacheco Blvd exits.  CA-4 is currently undergoing widening between Morello and CA-242 which will add a third lane in each direction, but no other improvements to the interchange are funded at this time.

The cloverleaf at I-680 and I-580 benefitted significantly when they added a flyover ramp from I-680 South to I-580 East, but a huge bottleneck still exists because of backups on the loop movement from I-580 West to I-680 South.

[CtrlAltDel]

880 to 101 would be a freeway to freeway interchange.  It would also be somewhat limited in height due to the approach paths for San Jose Airport.

kkt is correct - the San Jose airport is the primary reason for the lack of an upgrade to this interchange.  You can't add ramps above the interchange due to the approach paths to the airport.  (This is also why there isn't an interchange between I-880 and CA 87.)  Also, you can't put ramps below the interchange due to the high water table in that area.  US 101 (the lower of the two freeways) has intermittent pavement flooding problems, despite Caltrans having multiple pumps to keep the roadway dry.  So, we're stuck with the cloverleaf configuration.   

It's manifestly untrue that a flyover from I-880 to US-101 wouldn't be allowed because of the approach path to SJC. In addition to do being able to do it in the existing headroom, the blast fence at the end of runways 30 is almost as high as the flyover would have to be. SJC may be a reason for not making a US-101/CASR-87 interchange, but it certainly isn't the reason that US-101/I-880 hasn't been done, attempted, started, or well studied. My guesses are any combination of the following:
1) Construction costs
2) Possible Land Acquisition cost
3) Construction impact upon existing traffic (irony of ironies)
4) Recent construction in the area
5) Urbanist opposition to helping roads in any way.

I admit I'm not an expert on this, but I don't see how the I-880/US-101 interchange could affect the operations of the airport in any way. Assuming that the interchange is the red circle and the runways are the green lines, and I just can't see how a plane could swoop around from that interchange to line up with either of those two runways.

[kkt]

I'm not an expert either, but I wonder what an aircraft's go-around flight would look like when they have to abort a landing?

[michravera]

I'm not an expert either, but I wonder what an aircraft's go-around flight would look like when they have to abort a landing?

As someone who has landed, gone around, aborted landings, and done a large number of touch-and-go and stop-and-go landings and missed approaches on both runway 30R/12L and a few on 30L/12R, I can tell you that I-880 and US-101 doesn't even enter into the calculation of anything that you do at SJC. When you abort a landing and either go around or go missed, the first thing that you do is to fly the runway heading for some distance (usually until you are basically over the Bay on the 30 runways and until you have passed Downtown on the 12 runways) before you start a turn. About the only thing that the I-880/US-101 interchange is any good for is a reference point to use for your (really) tight traffic pattern (which is 1000 ft MSL or about 950 ft AGL) and, even then, you usually are well outside of it. Most of the time, you are at about 400ft MSL (350 ft AGL) when you come over I-880. When they give you straight in, you usually keep it to over 2000 (sometimes cheat it to 1500) over Downtown. When I was flying a lot more, I often heard advisories of unlighted construction cranes as high as almost 400 ft within a mile of the airport. Basically, no one flies below 500 ft AGL unless they have just taken off or are landing in the next 10-20 seconds, or are having troubles. The parking garage and likely the blast fence are higher than a flyover ramp would have to be and they are on the airport property. An I-880/US-101 interchange improvement may not get built in time to matter, for a lot of reasons, but the airport isn't one of them.

[sparker]

880 to 101 would be a freeway to freeway interchange.  It would also be somewhat limited in height due to the approach paths for San Jose Airport.

kkt is correct - the San Jose airport is the primary reason for the lack of an upgrade to this interchange.  You can't add ramps above the interchange due to the approach paths to the airport.  (This is also why there isn't an interchange between I-880 and CA 87.)  Also, you can't put ramps below the interchange due to the high water table in that area.  US 101 (the lower of the two freeways) has intermittent pavement flooding problems, despite Caltrans having multiple pumps to keep the roadway dry.  So, we're stuck with the cloverleaf configuration.   

It's manifestly untrue that a flyover from I-880 to US-101 wouldn't be allowed because of the approach path to SJC. In addition to do being able to do it in the existing headroom, the blast fence at the end of runways 30 is almost as high as the flyover would have to be. SJC may be a reason for not making a US-101/CASR-87 interchange, but it certainly isn't the reason that US-101/I-880 hasn't been done, attempted, started, or well studied. My guesses are any combination of the following:
1) Construction costs
2) Possible Land Acquisition cost
3) Construction impact upon existing traffic (irony of ironies)
4) Recent construction in the area
5) Urbanist opposition to helping roads in any way.

My initial guess as a local would be the Koll "North 4th" industrial park immediately adjacent to the SB 101>SB 880 ramp; Koll owns a shitload of commercial property in Santa Clara County and seems to have a great deal of political pull.  That industrial park was built in the early '80's (my business almost relocated there in '86), displacing a trailer park and old steel wartime industrial structures, so it's likely that the company would rather not have to downsize their holdings.  Since 880 makes a 45-degree turn through the 101 interchange, it's probable that any revision would to some degree "straightline" that curve, which itself would require movement west -- right into the Koll park.  Also the UP Milpitas branch, which is an active rail line, crosses 101 immediately south of the interchange; it would likely pose as an obstacle to expansion in that direction.  There's just no solution to 101/880 that wouldn't require tweaking the nose of corporate interests that would undoubtedly push back with every tool in the bag!   

[kkt]

The 1 to 2 story light industrial park adjacent to the interchange doesn't seem like that much of a problem.  This is not homes or landmark structures that people have fallen in love with.  A good buyout offer, relocation expenses, and a generous timeline for relocation should be sufficient.  Same for the other three sides, really, the car- and truck-oriented businesses there should be possible to relocate.  The railroad would be a problem to move, but it's 1600 feet from the center of the interchange so it seems like it should be possible to rebuild the interchange while leaving it in place. 

The adjacent interchanges along both I-880 and US 101 are closer than would be ideal.

As someone who has landed, gone around, aborted landings, and done a large number of touch-and-go and stop-and-go landings and missed approaches on both runway 30R/12L and a few on 30L/12R, I can tell you that I-880 and US-101 doesn't even enter into the calculation of anything that you do at SJC. When you abort a landing and either go around or go missed, the first thing that you do is to fly the runway heading for some distance (usually until you are basically over the Bay on the 30 runways and until you have passed Downtown on the 12 runways) before you start a turn. About the only thing that the I-880/US-101 interchange is any good for is a reference point to use for your (really) tight traffic pattern (which is 1000 ft MSL or about 950 ft AGL) and, even then, you usually are well outside of it. Most of the time, you are at about 400ft MSL (350 ft AGL) when you come over I-880. When they give you straight in, you usually keep it to over 2000 (sometimes cheat it to 1500) over Downtown. When I was flying a lot more, I often heard advisories of unlighted construction cranes as high as almost 400 within a mile of the airport. Basically, no one flies below 500 ft AGL unless they have just taken off or are landing in the next 10-20 seconds, or are having troubles. The parking garage and likely the blast fence are higher than a flyover ramp would have to be and they are on the airport property. An I-880/US-101 interchange improvement may not get built in time to matter, for a lot of reasons, but the airport isn't one of them.

Thanks for the benefit of your experience!

[sparker]

The 1 to 2 story light industrial park adjacent to the interchange doesn't seem like that much of a problem.  This is not homes or landmark structures that people have fallen in love with.  A good buyout offer, relocation expenses, and a generous timeline for relocation should be sufficient.  Same for the other three sides, really, the car- and truck-oriented businesses there should be possible to relocate.  The railroad would be a problem to move, but it's 1600 feet from the center of the interchange so it seems like it should be possible to rebuild the interchange while leaving it in place. 

The adjacent interchanges along both I-880 and US 101 are closer than would be ideal.

As someone who has landed, gone around, aborted landings, and done a large number of touch-and-go and stop-and-go landings and missed approaches on both runway 30R/12L and a few on 30L/12R, I can tell you that I-880 and US-101 doesn't even enter into the calculation of anything that you do at SJC. When you abort a landing and either go around or go missed, the first thing that you do is to fly the runway heading for some distance (usually until you are basically over the Bay on the 30 runways and until you have passed Downtown on the 12 runways) before you start a turn. About the only thing that the I-880/US-101 interchange is any good for is a reference point to use for your (really) tight traffic pattern (which is 1000 ft MSL or about 950 ft AGL) and, even then, you usually are well outside of it. Most of the time, you are at about 400ft MSL (350 ft AGL) when you come over I-880. When they give you straight in, you usually keep it to over 2000 (sometimes cheat it to 1500) over Downtown. When I was flying a lot more, I often heard advisories of unlighted construction cranes as high as almost 400 within a mile of the airport. Basically, no one flies below 500 ft AGL unless they have just taken off or are landing in the next 10-20 seconds, or are having troubles. The parking garage and likely the blast fence are higher than a flyover ramp would have to be and they are on the airport property. An I-880/US-101 interchange improvement may not get built in time to matter, for a lot of reasons, but the airport isn't one of them.

Thanks for the benefit of your experience!

The Koll group might have something to say about their industrial park being encroached upon; as I stated earler, they own a lot of properties in Santa Clara County and are quite well-connected.  But be that as it may -- although Caltrans doesn't usually entertain such things, a turbine-type interchange (a la Oak Park/US 50/CA 99/Biz 80) might well fit reasonably well into the space provided; while the turbine ramps may not be truly high-speed (guessing 35mph as average), it certainly would be an improvement over what's on the ground now!

[SeriesE]

US-101 N to I-880 S should be closed to improve weaving. Mainline traffic could use I-280 N to get to the freeway.

That leaves US-101 S to I-880 N. Not sure what could be done. Maybe a loop ramp from CA-87 S to I-880 N? That might not be possible because of the river.

[kkt]

Ramp statistics from CalTrans.  The most recent are 2010.  They released the spreadsheet in 2018 but many many ramps were not measured including the US 101-I-880 ones.  These are AADTs (no peak hour statistics for ramps).

101 NB to 880 NB ... 23,900
101 NB on from 880 NB ... 9,000
101 NB to 880 SB ... 9,100

101 SB to 880 SB ... 7,900
101 SB on from 880 SB ... 23,300
101 SB to 880 NB ... 4,800
101 SB on from 880 NB ... 10,600

[kkt]

The 1 to 2 story light industrial park adjacent to the interchange doesn't seem like that much of a problem.  This is not homes or landmark structures that people have fallen in love with.  A good buyout offer, relocation expenses, and a generous timeline for relocation should be sufficient.  Same for the other three sides, really, the car- and truck-oriented businesses there should be possible to relocate.  The railroad would be a problem to move, but it's 1600 feet from the center of the interchange so it seems like it should be possible to rebuild the interchange while leaving it in place. 

The adjacent interchanges along both I-880 and US 101 are closer than would be ideal.

As someone who has landed, gone around, aborted landings, and done a large number of touch-and-go and stop-and-go landings and missed approaches on both runway 30R/12L and a few on 30L/12R, I can tell you that I-880 and US-101 doesn't even enter into the calculation of anything that you do at SJC. When you abort a landing and either go around or go missed, the first thing that you do is to fly the runway heading for some distance (usually until you are basically over the Bay on the 30 runways and until you have passed Downtown on the 12 runways) before you start a turn. About the only thing that the I-880/US-101 interchange is any good for is a reference point to use for your (really) tight traffic pattern (which is 1000 ft MSL or about 950 ft AGL) and, even then, you usually are well outside of it. Most of the time, you are at about 400ft MSL (350 ft AGL) when you come over I-880. When they give you straight in, you usually keep it to over 2000 (sometimes cheat it to 1500) over Downtown. When I was flying a lot more, I often heard advisories of unlighted construction cranes as high as almost 400 within a mile of the airport. Basically, no one flies below 500 ft AGL unless they have just taken off or are landing in the next 10-20 seconds, or are having troubles. The parking garage and likely the blast fence are higher than a flyover ramp would have to be and they are on the airport property. An I-880/US-101 interchange improvement may not get built in time to matter, for a lot of reasons, but the airport isn't one of them.

Thanks for the benefit of your experience!

The Koll group might have something to say about their industrial park being encroached upon; as I stated earler, they own a lot of properties in Santa Clara County and are quite well-connected.  But be that as it may -- although Caltrans doesn't usually entertain such things, a turbine-type interchange (a la Oak Park/US 50/CA 99/Biz 80) might well fit reasonably well into the space provided; while the turbine ramps may not be truly high-speed (guessing 35mph as average), it certainly would be an improvement over what's on the ground now!

Maybe Koll would be unhappy with it, but I would think to a large property owner it's just another investment, and they don't feel any more personal about it than a bunch of stocks or bonds.  If they want that invested in an industrial park, they could buy or start another one.

[sparker]

^^^^^^^^^^^
The Koll park is actually a very nice, park-like complex (as I stated previously, I almost moved my business there in 1986, a few years after it opened); it would not only be the Koll company that would likely object to any significant encroachment but the tenants of the offices and warehouses in the park.  Approaching the issue as if it, or any particular property, is no more than a fungible entity doesn't take into consideration the commercial rental pricing in the South Bay; suggesting that an eminent domain settlement for taking a sizeable portion of the property would be considered appropriate compensation for both the relocation costs of the tenants plus the diminished recurring rental/lease revenue accruing to the property owners would likely be a non-starter in this case.  If any plans for revamping of the 101/880 interchange involve substantial encroachment on that office park, expect to see litigation in short order (unless Caltrans is prepared to "back up the Brinks truck" to Koll and the affected lessees).  But all this is speculation -- there are no plans for any interchange revision in the works presently; the current situation, substandard as it is, will probably stick around for at least the next decade.

[jrouse]

And this is why I said flyovers would be prohibitively expensive.  It's not the cost of the structures themselves but the cost of the right of way necessary to accommodate them and construct everything to modern standards.

[mrsman]

A shame that so many freeway to freeway interchanges were designed as cloverleafs when stacks do a much better job.  Of course, there is no feasible way to upgrade this 880/101 now, but I do wonder why this was chosen in the first place.  The 101/110 stack interchange in L.A. (even with its own issues) is a far better design than a cloverleaf.  The 101/110 interchange is older than this interchange so Caltrans could have put in a similar stack into the 101/880 interchange when it was first created.

[SeriesE]

A shame that so many freeway to freeway interchanges were designed as cloverleafs when stacks do a much better job.  Of course, there is no feasible way to upgrade this 880/101 now, but I do wonder why this was chosen in the first place.  The 101/110 stack interchange in L.A. (even with its own issues) is a far better design than a cloverleaf.  The 101/110 interchange is older than this interchange so Caltrans could have put in a similar stack into the 101/880 interchange when it was first created.

Maybe it's because the area used to be rural so the planners put the cheapest freeway-to-freeway interchange there, and didn't expect the explosive traffic and population growth decades later that would overwhelm the design. See also: I-680 and I-580 interchange.

[kkt]

Yes, the 101-880 interchange was contracted in 1960 when San Jose was a modest farm town.
See the photo-essay by Max Rockatansky at https://www.gribblenation.org/2018/01/california-state-route-17.html
with the relevant scan from California Highways and Public Works.

[Max Rockatansky]

^^^

Man, I worked over that article twice and somehow I don't even remember a lot of what I wrote.  Thankfully those CHPW volumes were pretty exacting in terms of finding specific dates of freeway openings.