Pavement on I-5 under overpasses in the southern Central Valley

[MarkF]

I took a trip up to San Francisco a few weeks ago, taking I-5 to go up there from Orange County.  Hit a huge jam for miles near the top of the reverse-side grade north of Castiac due to a fire caused by an accident.  Anyway, once that got moving again, I noticed that on the southern part of the I-5 Westside Freeway, the pavement under many of the overpasses was like in this view, asphalt nearly up to the bridge, then a short concrete section under the bridge, then a short asphalt section in the right lane just past the overpass, again a short concrete section, then back to asphalt:
https://goo.gl/maps/xuMQVNECfEnteniR9

Any idea of the logic for this?  I can see keeping the concrete section under the bridge to maintain clearance.  Also, looking at many of the overpasses, it seems the short asphalt stretches were only done on the northbound side.

Also, I took a video of the trip up I-5, from the end of the jam to I-80 at US 101 in San Francisco:
https://youtu.be/Y0PQjDROQyc

[jeffe]

Yes, you are correct that the concrete sections are left under the overpasses to prevent any reduction in clearance.  This usually only has to be done with older bridges, such as the the one in the link you provided which has a construction date of 1967 on the center column.  Bridges built after the 1970s were designed with sufficient clearance to allow for several layers of pavement to be added.

A good example of this is I-80 in Berkeley.  The concrete was left under the overpass at University Avenue when the freeway was repaved with asphalt and then a few years later the concrete section was replaced with new concrete using preformed panels.

When repaving occurs on roadways that are entirely asphalt, the pavement under an overpass is usually ground down to provide space for the new layer of asphalt.

As you noted, the asphalt on I-5 was only done on the northbound side.  On the southbound side the concrete in the slow lane was completely removed and replaced.  The new concrete is one foot wider and extends into the shoulder.  This is to allow for more even weight distribution from semi-trucks.  The original concrete on the northbound side ends right at the shoulder line.

[AndyMax25]

Same thing here along the Ventura Freeway US 101 at Louise Ave OC in the San Fernando Valley

https://goo.gl/maps/cBDBZihRwFccZsPd6

[sparker]

I took a trip up to San Francisco a few weeks ago, taking I-5 to go up there from Orange County.  Hit a huge jam for miles near the top of the reverse-side grade north of Castiac due to a fire caused by an accident.  Anyway, once that got moving again, I noticed that on the southern part of the I-5 Westside Freeway, the pavement under many of the overpasses was like in this view, asphalt nearly up to the bridge, then a short concrete section under the bridge, then a short asphalt section in the right lane just past the overpass, again a short concrete section, then back to asphalt:
https://goo.gl/maps/xuMQVNECfEnteniR9

Any idea of the logic for this?  I can see keeping the concrete section under the bridge to maintain clearance.  Also, looking at many of the overpasses, it seems the short asphalt stretches were only done on the northbound side.

Also, I took a video of the trip up I-5, from the end of the jam to I-80 at US 101 in San Francisco:
https://youtu.be/Y0PQjDROQyc

The first reply is correct regarding the reason for the repaving discontinuity under the overpass structures; this is done statewide and not just along the pre-'67 sections of I-5.  Also -- nice video; seems like someone else is giving Interstate Kyle some competition (I'm one of his Patreon contributing sponsors) -- albeit sped up significantly faster than his efforts. 

[Max Rockatansky]

Looks like the OP headed up to the Bay Area the weekend I went down to Ventura.  I recognize the aftermath of that brush fire near Lake Castiac.

[MarkF]

I took a trip up to San Francisco a few weeks ago, taking I-5 to go up there from Orange County.  Hit a huge jam for miles near the top of the reverse-side grade north of Castiac due to a fire caused by an accident.  Anyway, once that got moving again, I noticed that on the southern part of the I-5 Westside Freeway, the pavement under many of the overpasses was like in this view, asphalt nearly up to the bridge, then a short concrete section under the bridge, then a short asphalt section in the right lane just past the overpass, again a short concrete section, then back to asphalt:
https://goo.gl/maps/xuMQVNECfEnteniR9

Any idea of the logic for this?  I can see keeping the concrete section under the bridge to maintain clearance.  Also, looking at many of the overpasses, it seems the short asphalt stretches were only done on the northbound side.

Also, I took a video of the trip up I-5, from the end of the jam to I-80 at US 101 in San Francisco:
https://youtu.be/Y0PQjDROQyc

The first reply is correct regarding the reason for the repaving discontinuity under the overpass structures; this is done statewide and not just along the pre-'67 sections of I-5.  Also -- nice video; seems like someone else is giving Interstate Kyle some competition (I'm one of his Patreon contributing sponsors) -- albeit sped up significantly faster than his efforts.

Thanks.  I've been enjoying Interstate Kyle's posts for a while.  I sped up the Westside Freeway portion 30x and it still took a long time to get through there!  I don't think there is much you can do to make that stretch interesting, and the light was getting more and more out of my favor.  That 90 minute delay due to the fire north of Castiac didn't help any.