I thought this was the case based on a quick glance at the bridge location last week, got confirmation yesterday looking out the window of NB 769 as it passed over the new SD River bridge: the old SD River bridge is gone and work is now in progress on the new bridge piers, it would appear.
First trip on a Surfliner in many years and was impressed by condition of track surface northbound to Van Nuys. Not so much so in spots coming back down last night. Nice close-up view of Hobart Yard, though, very interesting (at least to me).
47 years and 9 days ago, the hot topic prior to the start of our 7:15am class was "did you feel the earthquake" that happened a bit over an hour earlier (I slept through the shaking). We were bit over 100 miles away, so the shaking was very mild, one classmate first thought it was his cat jumping on the bed. Later that day, we saw pictures of what was left of highway bridges over I-5 near Sylmar as well the concern over the Van Norman reservoir.
One high priority item for CalTrans was to find out why the bridge columns failed, the upshot was that there wasn't enough circumferential reinforcement to keep the concrete together when the columns wre swaying about in response to the earth shaking motions. When the concrete shattered, the vertical rebar buckled and the columns collapsed. The fix for the problem was to put about as much circumferential rebar as vertical rebar in future construction.
Fast forward to 1989 and the Loma Prieta earthquake. Post-Sylmar construction held up just fine, but a lot of the pre-Sylmar bridge columns failed. The response from the state and CalTrans is to start a program to reinforce existing bridges.
Fast forward again to 1994 and the Northridge earthquake. Reinforced pre-Sylmar bridges held up, bridges that were scheduled for reinforcement sometime in the future collapsed. State and CalTrans thus speed up the reinforcement program. The most common method for reinforcing cylindrical columns was to weld a steel jacket around the column, which serves to keep the concrete in place if it fractures during an earthquake. Another technique was to wrap the column with carbon fiber pre-preg and then cure the epoxy by heating the pre-preg. I got peripherally involved with working on NDE for the pre-preg.
What amused me about the San Diego River bridge desgn was reusing the tube used to keep soil out of the hole being prepared for the bridge column as part of the seismic reinforcement. Note that the bridge is almost on top of the Rose Canyon - Newport - Inglewood fault (a very recent discovery was that the Rose Canyon fault was an extension of the Newport Inglewood fault famous for prompting the Field Act of 1933).
On a slightly different note, I hope the designers were taking the experience of 180 into account. A week and a half of rainstorms had led to flooding in Mission Valley (San Diego river channel), with one reservoir overflowing and another about to. There was a forecast for the worst storm of the lot to show hit, but fortunately did not show up. The fear was with the second reservoir no longer able to hold the runoff, the bridges across the river channel would likely have been washed out.
erikemWhat impressed me was the tidbit about the heavy rail bridge being ~4' from the light rail bridge and trying verify that the bridges will not make contact during an earthquake.
You would be amused at some of the code generated during design of the refit of the Hernando DeSoto bridge (I-40 in Memphis). If you look at the interesting substitute for hinges that has been installed you will get an idea of how far the structure was expected to deflect and inherently self-restore with the mix of p- and s-waves from a potential deep-fault event.
Barely related, I suppose, but many long years ago there was a scrap yard alongside the (then) ATSF and visible from what was US 101. Front and center was a San Diego PCC. Reading the thread and seeing the map called it to mind. Looking at Google maps, the scrap yard appears to be gone. I wonder if the PCC is one that ended up in El Paso, or simply was converted into razor blades or toasters.
John Timm
I'm also a "rude" engineer, but did have one project where the meetings included work done by UCSD on verifying computer code of concrete columns subject to seismic shaking. They claimed that the code was doing a good job of matching the results from testing full sized columns at UCSD's lab. This was going on during the time that the various highway bridge columns were being reinforced with jackets.
What impressed me was the tidbit about the heavy rail bridge being ~4' from the light rail bridge and trying verify that the bridges will not make contact during an earthquake.
Stumbled onto a conference paper about the new bridge, given in 2016 at the AREMA conference, including the Powerpoint slides for the presentation. Kind of thick stuff for rude (non-civil) engineers, but still interesting.
Somewhat like the Taylor Street grade crossing in Old Town, where one has to cross two trolley and two regular tracks. Always dicey crossing because it's sometimes hard to gauge if there's enough room on the far side of the tracks, the decision being complicated by (usually) tourists making a panic lane change into the lane one wants because there is no warning of a "right turn only" lane until you are on the tracks. That crossing should really become an adventure when the mid-coast trolley route opens up in a few years, coupled with adding Amtrak and Coaster trains. I'm not sure about the current coordination with the crossing signals and the two signaled intersections because it's been a while since I've been there with trolley or train coming through.
I believe there is coordination at the Washington Street crossing in Mid-City, at least.
The signals have coordination with the crossing gates, the signal on San Elijo and Chesterfield will show green for eastbound traffic (away from the grade crossing) and block westbound traffic on Chesterfield. Similarly, left turns from southbound 101 are blocked when the gates are down. For those unfamiliar with the area highway 101, the tracks and San Elijo are parallel and run roughly north/south, with 101 on the west side of the tracks and San Elijo on the east side of the tracks. Chesterfield runs east/west, crosses San Elijo and the tracks and terminates in a Tee with 101.
The problem is not so much coordination of the traffic lights with the crossing signals as with coordiantion between the lights themselves. With the current single track at the crossing, there is room for maybe two cars on Chesterfield between the crossing and San Elijo. With two tracks, there might not be enough room for any cars, so the San Elijo signal would need to be set up to allow the crossing to clear - a worst case example is people waiting for the crosswalk to clear before completing the left turn onto San Elijo from Chesterfield.
erikemNCTD is making progress on the double track between Solana Beach and Cardiff, though the grade crossing at Chesterfield is gonna get interesting with the second track. That will probably require some coordination with the traffic lights on San Elijo and 101.
If the rubber wheel bubbas (MC's appropriate terminology) don't fully coordinate those signals, they are dumber than they look, and something bad will happen, perhaps more than once.
Precip probability is up to 60% for Monday night, but as you said will believe when I see it. Big question is whether to thank or blame MC's BossHen if the rains do show up.
NCTD is making progress on the double track between Solana Beach and Cardiff, though the grade crossing at Chesterfield is gonna get interesting with the second track. That will probably require some coordination with the traffic lights on San Elijo and 101.
erikem FWIW, no rain is forecast for the next week in the San Diego area. Temperatures will be 60's or 70's.
FWIW, no rain is forecast for the next week in the San Diego area. Temperatures will be 60's or 70's.
Now the weatherfeds are saying chance of showers starting on Monday at least out to Thursday. I'll believe it when I see it. Humidity was low enough that our plastic soda cups at lunch today had zip, zero, nada condensation on the outside down by the airport. And gosh, the highs will only be in the mid-sixties.
What would be cool is if a tunnel for the Surf Line (Coaster/Amtrak/BNSF) was placed between Sorrento Valley (about where the "e" is on "Voigt Drive") and Rose Canyon (just west of Genessee). The topper would be an underground Coaster station right under the Blue Line terminus at UTC, probably needing elevators...
RDG467 Trolley is going to UTC Mall in La Jolla, according to the San Diego Railfan group on the Facebook.
Trolley is going to UTC Mall in La Jolla, according to the San Diego Railfan group on the Facebook.
Drove over the area today and noticed that the dual tracking on the south has not yet been completed, as the two tracks from the south still merge to a single track south of the bridges. Work to be done, it would seem. But they got a good picture for the morning paper a couple of days ago.
Overmod Just a thought: It might be the angle or a camera artifact, but is there not substantial space between the bridge beams and the train, even for ballasted-deck? Could these two structures be repurposed to parallel double-track with one for the trolley when that time comes?
Just a thought:
It might be the angle or a camera artifact, but is there not substantial space between the bridge beams and the train, even for ballasted-deck? Could these two structures be repurposed to parallel double-track with one for the trolley when that time comes?
Doubtful. At present the bridge decks are about 16 feet or so in width. What is more interesting is how the trolley will be able to slip two additional tracks through a relatively narrow right-of-way just north of Friars Road.
Things have been getting pretty dry around here, would very much appreciate if BossHen can work her magic.
Sure about that? BossHen comes a-packin'
Thank you for the pre-trip safety briefing. Will leave the tin shoes in Iowa and lace-up the regular steel-toed tennies.
mudchickenfilled the moat and starved the alligators yet?
Not enough rain down here this year (2.03 inches water YTD) to fill the moat and the alligators have been filling up on winter tourists...so...no.
(Chuck: and we get to see and hear about the project on site Monday along with the mid-Coast LRT project - filled the moat and starved the alligators yet?)
Apparently the new bridge and track is now open:
http://www.sandiegouniontribune.com/news/sd-me-lossan-track-20180205-story.html
mudchicken (and our AREMA tribe has a field trip there 2/12)
(and our AREMA tribe has a field trip there 2/12)
Yeah, we get a lot of winter business traffic. When I was working, the customers in colder climes would schedule project reviews out here during the winter, for the most part. Seemed like our winter trips involved snow most of the time unless heading to Ft. Worth or EAFB; fortunately, those were few and far between.
Took a look at the progress on this project today and noticed that track is now in place on the new (western) bridge, though it is not connected yet on the south side of the river at least. I drove under the spans on Friars Road a few weeks ago and the new spans looked complete, including some fresh graffiti on the west side of the bridge.
As Paul noted above, the trolley extension to the north should be an interesting situation as there isn't a lot of remaining space to put the line through. I'm not sure what their plans are for that.
Chuck,
Thanks for the heads up. Looking forward to seeing more double track in North County, though not with the urgency when I was commuting to OC via Amtrak.
Trust the work wasn't adversely affected by the third highest crest of the San Diego River - remembering the fun from the second highest crest 37 years ago. The latter would have been a lot worse if the forecast storm had occurred with El Capitan on the verge of spilling.
- Erik
In perusing that SANDAG material, the bridging you mentioned is only half of the river crossing, used by Amtrak, BNSF, and Coaster. The other half is a future bridge (two-tracks) for the San Diego Trolley’s Blue Line extension northward. Four-tracks is going to make quite a river crossing!
----------------------------------------------------------------------------------------------------------------------------------- K.P.’s absolute “theorem” from early, early childhood that he has seen over and over and over again: Those that CAUSE a problem in the first place will act the most violently if questioned or exposed.
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