I-580/I-680 Interchange in Pleasanton, CA

[ZLoth]

On occassion, I had to travel from Sacramento to San Jose. Rather than fight the traffic, I end up taking I-5 south to the I-205 spur, which turns into I-580. It's a pleasant route....except for the I-580/I-680 Interchange.

Oh, good god, do I hate going from Westbouind I-580 to Southbound I-680 on this interchange. I cannot count how many times I was almost in a accident trying to dodge a semi transitioning from northbound I-680 to westbound I-580 in that cloverleaf. Even my GPS recommends going southbound on CA-84 to avoid this deathtrap. When was this interchange designed? 1962?

[TheStranger]

On occassion, I had to travel from Sacramento to San Jose. Rather than fight the traffic, I end up taking I-5 south to the I-205 spur, which turns into I-580. It's a pleasant route....except for the I-580/I-680 Interchange.

Oh, good god, do I hate going from Westbouind I-580 to Southbound I-680 on this interchange. I cannot count how many times I was almost in a accident trying to dodge a semi transitioning from northbound I-680 to westbound I-580 in that cloverleaf. Even my GPS recommends going southbound on CA-84 to avoid this deathtrap. When was this interchange designed? 1962?

CalTrans bridge log notes one of the structures at that junction does date back to 1965.  (That would make sense: not sure any part of today's 680 freeway except north of Benicia was ever signed as Route 21, which was originally on the parallel surface road).

In any case, when I used to have to travel from Sacramento to the South Bay (mostly for Sharks games) I always took the 84 cutoff to save a few miles and avoid 680/580.

[kurumi]

It used to be a regular cloverleaf with C/D roads until about c. 2002, when IMHO they upgraded the wrong turning motion to a flyover. But a manager in the area said that, at the time the project was conceived, 680 SB to 580 EB was the most congested movement in the interchange.

[myosh_tino]

But a manager in the area said that, at the time the project was conceived, 680 SB to 580 EB was the most congested movement in the interchange.

That manager must have been high when he made those comments.  If they had built a new WB 580 to SB 680 ramp, that would have alleviated TWO backups.  Instead, they built a ramp that alleviated ONE backup. 

[DTComposer]

But a manager in the area said that, at the time the project was conceived, 680 SB to 580 EB was the most congested movement in the interchange.

That manager must have been high when he made those comments.  If they had built a new WB 580 to SB 680 ramp, that would have alleviated TWO backups.  Instead, they built a ramp that alleviated ONE backup. 

I was thinking the same thing - that was right near the height of the dot-com boom, and with all those people commuting from San Joaquin County into Silicon Valley, I can't imagine why a W580 to S680 flyover wasn't the greatest need.

[mrsman]

But a manager in the area said that, at the time the project was conceived, 680 SB to 580 EB was the most congested movement in the interchange.

That manager must have been high when he made those comments.  If they had built a new WB 580 to SB 680 ramp, that would have alleviated TWO backups.  Instead, they built a ramp that alleviated ONE backup. 

I was thinking the same thing - that was right near the height of the dot-com boom, and with all those people commuting from San Joaquin County into Silicon Valley, I can't imagine why a W580 to S680 flyover wasn't the greatest need.

It is curious as to why SB to EB  would have been a big traffic movement.  Was the Walnut Creek / Concord area a major destination for Central Valley?  I can't imagine, even in the pre-Silicon Valley era, that this would have ever been a big movement.

[myosh_tino]

It is curious as to why SB to EB  would have been a big traffic movement.  Was the Walnut Creek / Concord area a major destination for Central Valley?  I can't imagine, even in the pre-Silicon Valley era, that this would have ever been a big movement.

It isn't.

However, SB 680 to EB 580 traffic had to interact with all of the traffic from WB 580 transitioning to SB 680.  The result was it caused major backups on SB 680.  The thought was if one of the two SB 680 loop ramps were replaced with a flyover, it would ease traffic on the remaining loop ramp.  Unfortunately, the wrong loop ramp was removed (SB 680 to EB 580). 

There are plans in the works to build a flyover ramp from WB 580 to SB 680 but there's no money to build it.  Alameda county had a 1/2 cent sales tax measure on the ballot in 2012 that would have funded such a ramp but it failed to get the 2/3rds super majority needed to pass.  It got 66.53% of the vote but needed 66.67% to pass (yes, that's a difference of 0.14% or about 750 votes  ).

[ARMOURERERIC]

It used to be a regular cloverleaf with C/D roads until about c. 2002, when IMHO they upgraded the wrong turning motion to a flyover. But a manager in the area said that, at the time the project was conceived, 680 SB to 580 EB was the most congested movement in the interchange.

When they say: "When the project was conceived" they may be talking a good 10 years prior when the EIS started

[mrsman]

I had an additional idea about this interchange:

I know there were plans for an I-5W in the old days.  Basically, a roadway that connects I-505 in Vacaville with I-580 near Tracy.  It would provide a bypass of Stockton and Sacramento for I-5 thru traffic.  Until such time as the roadway was to be built, perhaps the powers that be felt that the best route to make the missing connection would be I-580 to I-680 to I-80 to I-505.  And if that were the case, then the connection from I-680 south to I-580 east would be a heavy movement. 

Of course, now the drive through Walnut Creek and Fairfield is much busier than the drive through Sacramento, so nobody would ever utilize this routing as any sort of bypass.

[Concrete Bob]

Actually, Interstate 5W was to continue into Oakland along the current Interstate 580, and was briefly (about a year) signed as Interstate 5W (and US 50) in Oakland when it opened in 1962 or so.  My guess is that Interstate 5W would have continued co-signed with Interstate 80 and then broke off at the current Interstate 505. 

Still, I would agree that there should be a big soaring flyover from westbound Interstate 580 to southbound 680 to make that interchange completely functional for the region it serves.  The adjacent upgraded SR 84 is nice, but a new W-S flyover would help traffic flow immensely in the area. 

[TheStranger]

Still, I would agree that there should be a big soaring flyover from westbound Interstate 580 to southbound 680 to make that interchange completely functional for the region it serves.  The adjacent upgraded SR 84 is nice, but a new W-S flyover would help traffic flow immensely in the area. 

I do wonder if CalTrans felt that the current widening project on 84 between 580 and 680 would be a cheaper alternative to building that flyover...

[flowmotion]

It used to be a regular cloverleaf with C/D roads until about c. 2002, when IMHO they upgraded the wrong turning motion to a flyover. But a manager in the area said that, at the time the project was conceived, 680 SB to 580 EB was the most congested movement in the interchange.

When they say: "When the project was conceived" they may be talking a good 10 years prior when the EIS started

Right, there's a major employment center at Bishop Ranch in San Ramon, just to the north. It's not hard to believe that back when real estate was less expensive and people lived closer to work that SB to EB would have been the larger movement.