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Author Topic: California  (Read 430237 times)

sparker

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Re: California
« Reply #75 on: August 19, 2016, 02:58:39 PM »

Considering the topography, the transfer requirements of the freeways involved, and the land-use politics of East Los Angeles and environs, it's likely the East L.A. interchange (5/10/60/101) will remain largely as it is for the foreseeable future -- there's hardly enough room to expand the through-put lanes for I-5 much less a full revamping of the facility. 
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AsphaltPlanet

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Re: California
« Reply #76 on: August 19, 2016, 04:02:24 PM »

^ Yeah, I agree with that, but I am thinking that at some point in the future the structures that comprise the East LA Interchange complex will reach the end of their service life, and will need to be somehow replaced.  I live in a northern climate, so structural replacement is probably something that afflicts our infrastructure sooner than it would in California, but I have to think eventually the East LA interchange will need to be remade into something that is really cool.
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SeriesE

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Re: California
« Reply #77 on: August 19, 2016, 04:38:48 PM »

^ Yeah, I agree with that, but I am thinking that at some point in the future the structures that comprise the East LA Interchange complex will reach the end of their service life, and will need to be somehow replaced.  I live in a northern climate, so structural replacement is probably something that afflicts our infrastructure sooner than it would in California, but I have to think eventually the East LA interchange will need to be remade into something that is really cool.
Yeah. At this point it will probably take a discovery of some serious structural failure(s) before any plans to rebuild will even be considered.

Maybe someone will pull a fast one and declare the complex as historical, thus preventing any upgrades or rebuilds.  :-D
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sparker

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Re: California
« Reply #78 on: August 20, 2016, 01:16:25 PM »

Having used this interchange for most of its 55-year existence, I'm certain that most drivers would be glad to place it in a particular historical subsection -- the WTF Hall of Fame!  This particularly pertains to drivers wishing to stay on I-5 in either direction through the complex -- and encountering a small-radius curve en route, not to mention the merges from hell!  I'm guessing that the engineering effort contained numerous "plan-it-as-we-go" moments. 
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Exit58

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Re: California
« Reply #79 on: August 20, 2016, 06:23:07 PM »

Having used this interchange for most of its 55-year existence, I'm certain that most drivers would be glad to place it in a particular historical subsection -- the WTF Hall of Fame!  This particularly pertains to drivers wishing to stay on I-5 in either direction through the complex -- and encountering a small-radius curve en route, not to mention the merges from hell!  I'm guessing that the engineering effort contained numerous "plan-it-as-we-go" moments.

Technically what is now the 5 is running on two different freeway. The 101 was originally the through route, in this case the Hollywood and Santa Ana Freeways which are still a through route. The Golden State was US 99 which actually went east on the San Bernardino. The connection from the San Bernardino to the Santa Ana was probably treated like the western segment of the San Bernardino is today: a connector. My question is, when the interchange opened, did the Santa Monica even have a signed number? Or just temp I-10?

I think it was more poor future-planning on Caltrans part then anything else. They wanted the 101 to be the primary route through the interchange and didn't really care what the legislators were planning numbering wise.
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TheStranger

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Re: California
« Reply #80 on: August 20, 2016, 08:38:53 PM »

My question is, when the interchange opened, did the Santa Monica even have a signed number? Or just temp I-10?

IIRC, while the Olympic Parkway around that corridor had been planned as pre-1964 State Route 26, by the time the Santa Monica Freeway was built (including that part of the East Los Angeles Interchange), it was I-10 from the start.

I think it was more poor future-planning on Caltrans part then anything else. They wanted the 101 to be the primary route through the interchange and didn't really care what the legislators were planning numbering wise.

I don't know if it was "want" so much as, as the Santa Ana Freeway was the first through the area, they didn't want to disrupt the one through route that had already been established.  (If we were thinking simple lines-on-map layout, having 5 tie into the San Bernardino Split so that there was no need for that 2 miles of parallel north-south freeway routings would have been the most logical, but this could have been a matter of what right of way the state was able to acquire at the time)

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Chris Sampang

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Re: California
« Reply #81 on: August 21, 2016, 07:18:44 AM »

My question is, when the interchange opened, did the Santa Monica even have a signed number? Or just temp I-10?

IIRC, while the Olympic Parkway around that corridor had been planned as pre-1964 State Route 26, by the time the Santa Monica Freeway was built (including that part of the East Los Angeles Interchange), it was I-10 from the start.

I think it was more poor future-planning on Caltrans part then anything else. They wanted the 101 to be the primary route through the interchange and didn't really care what the legislators were planning numbering wise.

I don't know if it was "want" so much as, as the Santa Ana Freeway was the first through the area, they didn't want to disrupt the one through route that had already been established.  (If we were thinking simple lines-on-map layout, having 5 tie into the San Bernardino Split so that there was no need for that 2 miles of parallel north-south freeway routings would have been the most logical, but this could have been a matter of what right of way the state was able to acquire at the time)

Yes, the whole ELA interchange and SB Split interchange would make a lot more sense if it were designed in a way that provided for three main freeway routings with ramps connecting the three.  So for instance:

1) Hollywood <101> - San Bernardino <10>
2) Golden State <5> - Santa Ana <5>
3) Santa Monica <60> - Pomona <60>

To reinforce the point, the Santa Monica freeway would be 60 instead of 10.

(1) and (2) would interchange where the 5/10 interchange near County-USC Hospital.  It would be designed as a regular interchange with movements in all directions.  Since the interchange between (1) and (2) would provide the movement from Hollywood to Santa Ana, the 101 freeway between SB Split and the E LA interchange would be superflous and would be removed.

The interchange between (2) and (3) would now be much more simplified without the 101.  Essentially an east-west freeway interchanging with a north-south freeway that makes a sharp turn to the southeast just south of the interchange.  Again, movements in all directions would be provided.

There would be no direct interchange between (1) and (3).  For the most part (1) and (3) are parallel to each other and remain about 3-10 miles apart from the 110 all the way to where they meet in Beaumont.  Traffic between Hollywood and Pomona or between Santa Monica and San Bernardino could use any of the following freeways to connect between (1) and (3):  110, I-5, I-710, I-605, CA-57 or CA-71, I-15, or I-215. There is no good reason to funnel all of this traffic through I-5 as what is currently done by signing I-10 along the Golden State or on the 101 between SB Split and ELA interchange.

If this were done, there would be nothing special about the SB Split or ELA interchanges.  Instead they would be two regular freeway interchanges that happen to lie about 2-3 miles east of Downtown LA.

Of course, historically the 101 as a through route from Hollywood to Santa Ana predated all of the interchanges, and the powers that be probably thought that it would be wasteful to rip up the 101 routing between SB Split and ELA interchange so we are left with what we have.  There was no good way to connect I-5 Golden State Freeway to match up with this part of the 101  because the railroad yard was in the way.
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sparker

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Re: California
« Reply #82 on: August 21, 2016, 02:10:28 PM »

I was 11-12 years old at the time the interchange opened; it was completed in phases.  The first sections to be completed, in early 1961, were the ramps forming the direct I-5 connection, from the SE Santa Ana Freeway (at that time still signed as US 101) to the Golden State Freeway (I-5/10).  The San Bernardino Freeway interchange a couple of miles north on the Golden State had been completed and opened in early 1960 (and, for a while, there was a BGS on westbound I-10 just before that interchange showing the through lanes of the San Bernardino Freeway as I-110; it was gone by 1963).  Until the I-5 throughput ramps were opened, the freeway temporarily terminated at Boyle Ave. near Hollenbeck Lake.  The I-10 through ramps from the Golden State to the westerly Santa Monica freeway opened right around Christmas of 1961; it simply directed traffic to Santa Fe Avenue (and, IIRC, was temporarily signed as such, minus any I-10 reference).  The entire Santa Monica viaduct south of downtown LA was completed to the Harbor Freeway (then US 6/CA 11) in late 1962; the ramps from the SE Santa Ana Freeway to the Santa Monica were opened at that time as well; all signage clearly indicated I-10.  The multiplex of I-5 and I-10 was acknowledged by a roadside BGS northbound; the only freestanding signage featuring both I-5 and I-10 shields was southbound immediately after the WB I-10 merge from the San Bernardino Freeway; that signage lasted several years but was gone by the late '60's. 

California Highways & Public Works gave sparse coverage to the interchange itself, but the coverage of the I-10/Santa Monica Freeway viaduct (then the longest such structure on the state highway system) was the subject of articles as well as multiple photographs.  Worth checking out! 
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TheStranger

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Re: California
« Reply #83 on: August 22, 2016, 06:50:54 AM »

I was 11-12 years old at the time the interchange opened; it was completed in phases.  The first sections to be completed, in early 1961, were the ramps forming the direct I-5 connection, from the SE Santa Ana Freeway (at that time still signed as US 101) to the Golden State Freeway (I-5/10).

Given that 101 and 5 remained concurrent in Orange County as late as 1967, I've always felt that the southbound 5/101 signage on the northernmost part of the Santa Ana Freeway was a vestige of that history.  (Similarly, I've seen a 1984 video on Youtube of I-80 west in San Francisco where the mainline is signed as "I-80/US 101" - which doesn't make sense from a modern perspective at all, but which likely was one of the few remaining hints at the intended 80/101 concurrency along the existing Central Freeway segment to the never-constructed Western Freeway)

The San Bernardino Freeway interchange a couple of miles north on the Golden State had been completed and opened in early 1960 (and, for a while, there was a BGS on westbound I-10 just before that interchange showing the through lanes of the San Bernardino Freeway as I-110; it was gone by 1963).

Wow, I never knew that the 1960s I-110 was signed in any way!  (Legislatively, it lasted until 1968; IIRC when the Century Freeway was added to the Interstate system, the Interstate mileage from this and from I-480 in San Francisco was transferred to the new project)

Was 1960s I-105 (the portion of US 101/Santa Ana Freeway between the San Bernardino Split and East Los Angeles Interchange) ever signed too?

Of course, historically the 101 as a through route from Hollywood to Santa Ana predated all of the interchanges, and the powers that be probably thought that it would be wasteful to rip up the 101 routing between SB Split and ELA interchange so we are left with what we have.  There was no good way to connect I-5 Golden State Freeway to match up with this part of the 101  because the railroad yard was in the way.

Another thought that has come to mind in looking at the layouts:

The I-10 routing snaking through the Golden State Freeway to connect the San Bernardino Freeway and Santa Monica Freeway seems to be a product of two things, 1. that the San Bernardino Freeway is the oldest east-west controlled access route in the area (and thus could easily be given the I-10 signage right away) whereas the Pomona Freeway was mostly constructed decades after the San Bernardino had been completed, and 2. while the Santa Monica Freeway had been proposed as Route 26/Olympic Parkway beforehand, by the time it opened, it had become part of the extended I-10.

The other factor that came to mind: the limited capacity of the Four-Level Interchange, with its 35 MPH ramps, and of the downtown freeways in general.  In theory, one can connect from the Santa Monica to San Bernardino freeways by staying on the left through lanes that connect 10 east to Harbor Freeway north, then head east on the Santa Ana Freeway to the San Bernardino Split (and vice versa westbound), but the heavy traffic that has plagued downtown since the 1950s makes this even less viable than going through a cramped, but Interstate-standard connection in East Los Angeles.  Likewise, while the Hollywood Freeway extension north of Route 134 that had been proposed in the 1950s (as US 6) did create a through north-south route from the San Fernando Valley into downtown, the narrow right of way of the downtown slot segment of the Santa Ana Freeway limits any capacity expansion to this day.

(It's also important to remember that prior to the Golden State Freeway construction from Elysian Park to the San Bernardino Freeway, 99 and 6 had to continue southwest into downtown on the Arroyo Seco Parkway before reaching the San Bernardino Freeway rather indirectly via 101; the I-5/at-the-time US 99 routing between those two points saves about 4-5 miles of driving and bypasses the Four-Level entirely)

So much like the US 395/I-15 saga in the Inland Empire, or even the 1950s I-5/US 99 alignment planning in the San Joaquin Valley - where a bypass of an older through route was added to the Interstate system in order to fund new-build construction instead of in-place upgrades - it seems the Golden State Freeway south of today's Route 170 and the Santa Monica Freeway east of today's 110 both were intended as bypasses of already-existing through freeways that are even harder to widen/upgrade than the San Bernardino and Atwater/Merced examples I mentioned.  Even if that made the East Los Angeles Interchange itself rather complex, it provided for alternates to having to slog through the civic center and Hollywood areas.
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Chris Sampang

coatimundi

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Re: California
« Reply #84 on: August 23, 2016, 01:18:53 AM »

(It's also important to remember that prior to the Golden State Freeway construction from Elysian Park to the San Bernardino Freeway, 99 and 6 had to continue southwest into downtown on the Arroyo Seco Parkway before reaching the San Bernardino Freeway rather indirectly via 101; the I-5/at-the-time US 99 routing between those two points saves about 4-5 miles of driving and bypasses the Four-Level entirely)

Maybe a bit stupid or off-topic, but was the section of the Golden State Freeway north of Arroyo Seco, along the river, constructed before the section south of that? Because I've always thought it funny that the old Riverside Drive ramps from Arroyo Seco were (and still are) used for its I-5 connection.
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sparker

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Re: California
« Reply #85 on: August 23, 2016, 03:14:37 AM »

The first section of the Golden State Freeway (eventual I-5) to be constructed & opened was between Riverside Drive near the L.A. Zoo in Griffith Park and Alameda Ave. in Burbank; that was opened in early 1957.  By the end of that year it had been extended south to between Glendale Blvd. and Los Feliz Blvd, using temporary ramps to empty out onto Riverside Drive.  Included in that segment was the Colorado Blvd. extension (part of LRN 161/SSR 134).  By mid-1958 US 99/6 had been rerouted onto the freeway using the Colorado extension (an arrangement that lasted for about 3 years).  Northbound, US 99/6 remained on San Fernando Road (the original alignment) to the Colorado extension, then used that extension to the freeway mainline.  It went north on the freeway to Alameda, where it turned west with SSR 134 to Victory Blvd.  At Victory Blvd. the temporary routing turned north, using that street to the "Five Point" intersection of Victory Blvd., Burbank Blvd., and Victory Place.  While Victory Blvd. turned due west at that intersection, the 99/6 temporary routing continued north on Victory Place, which merged with the original San Fernando Road alignment east of Lockheed (now Hollywood/Burbank) airport.  This rerouting was necessary because northward construction on the Golden State Freeway used the alignment of Front Street, the former route, in central Burbank; the street was demolished in late 1957 to make room for the freeway, which was opened to traffic as far north as Burbank Blvd. in the spring of 1959. 

The segment along Riverside Drive, which included the SSR 2/Glendale Freeway interchange, was opened to traffic in the spring of 1961; southbound, it emptied all US 99/6 traffic onto the southbound Pasadena Freeway over the present ramp system bordering Elysian Park.  The first Golden State Freeway section to actually receive I-5 signage, between Broadway on the north and Boyle St. on the south (near Hollenbeck Lake, just north of Wilshire Blvd., and including the San Bernardino Freeway interchange), had opened in early 1960, with the I-5 ramps to the southbound Santa Ana Freeway (US 101) opening a year later.  The final section, between Broadway and just north of the Pasadena Freeway (including the interchange with that freeway, then US 66, and the L.A. river bridge) opened in late 1962. 

North of Burbank, the segment between Burbank Blvd. and Lankershim Blvd. in Sun Valley opened in the spring of 1961, extending north to Van Nuys Blvd. in early 1963 (this section included the inital ramps to the planned Hollywood Freeway -- originally intended to be part of US 6, but, after the '64 renumbering, becoming CA 170).  The final I-5 segment between Van Nuys Blvd. and the existing Golden State Freeway alignment north of Sylmar was opened to traffic in the fall of 1963, essentially finishing the freeway from its inception at the E.L.A. interchange to the point where it departed the San Fernando Valley. 

As a born & raised Glendale kid, I had front-row seating for the unfolding of this freeway -- I remember badgering my dad to drive me over the temporary Victory Blvd. alignment so I could see how it was signed (and as long as we were out that far in Burbank, to take me to Albin's Hobbies so I could see the new Lionel locomotives for '58 Xmas!).  If it was anything that rolled along the ground, it interested me as a youngster (some things never change!).
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djsekani

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Re: California
« Reply #86 on: August 23, 2016, 10:33:07 PM »

Found an article that some of you have probably seen before talking about why Southern Californians add a "the" when talking about their freeways. Some cool old-school scans and photos in here too.

https://www.kcet.org/shows/lost-la/the-5-the-101-the-405-why-southern-californians-love-saying-the-before-freeway-numbers
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sparker

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Re: California
« Reply #87 on: August 24, 2016, 01:57:35 AM »



Maybe a bit stupid or off-topic, but was the section of the Golden State Freeway north of Arroyo Seco, along the river, constructed before the section south of that? Because I've always thought it funny that the old Riverside Drive ramps from Arroyo Seco were (and still are) used for its I-5 connection.
  When I, as an 11-year-old kid, first saw that they were using the original Riverside Drive ramps as a connection to and from I-5 to the southward (then) Pasadena Freeway, my reaction was the kid's version of WTF?  I always thought those ramps were substandard even as a street connector much less carrying the brunt of southbound I-5 traffic toward downtown L.A.!  But 55 years later, it's still there (although having been repaved and restriped countless times).  I'm guessing that tearing out the cliff to cobble together a set of high-speed ramps was a non-starter, considering the land was a city park (the 2nd largest in L.A. after Griffith, slightly to the north).  Adding flyovers to the Pasadena Freeway twin bridges over the L.A. river was probably dismissed as well due to the configuration of those bridges.  Likely the Division of Highways did what it could with the cards it was dealt -- although in reality the hand was dealt by the Division itself 20-25 years previously when the Arroyo Seco Parkway was in the planning stages.  At that time the proposed L.A. freeway system was largely radial in nature, centering on downtown; the Interstate loops weren't even a pipedream in the mid-30's. 
« Last Edit: August 24, 2016, 02:00:13 AM by sparker »
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sdmichael

Re: California
« Reply #88 on: August 24, 2016, 02:53:54 PM »



Maybe a bit stupid or off-topic, but was the section of the Golden State Freeway north of Arroyo Seco, along the river, constructed before the section south of that? Because I've always thought it funny that the old Riverside Drive ramps from Arroyo Seco were (and still are) used for its I-5 connection.
  When I, as an 11-year-old kid, first saw that they were using the original Riverside Drive ramps as a connection to and from I-5 to the southward (then) Pasadena Freeway, my reaction was the kid's version of WTF?  I always thought those ramps were substandard even as a street connector much less carrying the brunt of southbound I-5 traffic toward downtown L.A.!  But 55 years later, it's still there (although having been repaved and restriped countless times).  I'm guessing that tearing out the cliff to cobble together a set of high-speed ramps was a non-starter, considering the land was a city park (the 2nd largest in L.A. after Griffith, slightly to the north).  Adding flyovers to the Pasadena Freeway twin bridges over the L.A. river was probably dismissed as well due to the configuration of those bridges.  Likely the Division of Highways did what it could with the cards it was dealt -- although in reality the hand was dealt by the Division itself 20-25 years previously when the Arroyo Seco Parkway was in the planning stages.  At that time the proposed L.A. freeway system was largely radial in nature, centering on downtown; the Interstate loops weren't even a pipedream in the mid-30's.

Also consider that large cliff is unstable, having slid quite substantially in the 1937. Yeah, it is a bit harrowing at times, but then it still somehow manages to carry that traffic. Caltrans has done some reworking of that ramp, mostly at the merge with SB 110 by adding a lane and reducing the amount of merging required for SB 5 to SB 110 traffic.
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sparker

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Re: California
« Reply #89 on: August 24, 2016, 03:47:06 PM »

I'll have to admit that the (current) I-5 to SB CA 110 ramps have at least stood the test of time, despite the fact that the ramps contain two harrowing curves in each direction: the ones immediately prior to the 110 merge (SB) and the initial curve out of the tunnel (NB) -- and the parallel curves that snake along the hillside where the original ramps emptied out onto Riverside Drive, but were built in the present configuration to allow the relocated Riverside Drive to make an abrupt right-angle turn.  IMO, these are at least as bad as the curves right at 110.
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AndyMax25

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Re: California
« Reply #90 on: August 24, 2016, 08:42:40 PM »

Just saw this on a tweet from Caltrans D7. It's a non-standard US shield and missing Freeway Entrance sign. This is NB 101 on ramp from Universal Studios.  Never seen anything like this and strange that hey chose this anomaly for a public notice.

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jeffe

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Re: California
« Reply #91 on: August 24, 2016, 10:56:19 PM »

Just saw this on a tweet from Caltrans D7. It's a non-standard US shield and missing Freeway Entrance sign.

Stranger still, prior to November 2014 there were not any entrance assembly signs at this ramp at all, according to the pictures on Google Street View.  The only indications for this ramp was the sign directing traffic to North and South 101.

The side without the Freeway Entrance sign is on a square metal post, as opposed to a wood post for the complete assembly.  The City of Los Angeles uses square metal posts for all of their signs, so perhaps this is a City installation?

As for the missing Freeway Entrance sign, I've seen Caltrans do this on ramps leading to an expressway segment, because the ramp is technically not a freeway entrance.  Here's an example:

« Last Edit: August 26, 2016, 09:32:31 PM by jeffe »
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sparker

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Re: California
« Reply #92 on: August 25, 2016, 01:14:19 AM »

Maybe the sign's from the prop department at Universal!  :biggrin:
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Exit58

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Re: California
« Reply #93 on: August 25, 2016, 11:30:15 PM »

I used to frequent Universal and that interchange was always a mess. I didn't know that they (finally) added a direct connection from Universal Blvd to SB101. I remember always having to drive quite a way south on Cahuenga Blvd to get on.

Also, it looks like just north of the new SB101 onramp, there is a US 101 shield with green NORTH and directional arrow tabs. The northbound onramp from NB Universal is also using painted posts for it's entrance assembly.
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Occidental Tourist

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Re: California
« Reply #94 on: August 26, 2016, 06:52:34 PM »



Maybe a bit stupid or off-topic, but was the section of the Golden State Freeway north of Arroyo Seco, along the river, constructed before the section south of that? Because I've always thought it funny that the old Riverside Drive ramps from Arroyo Seco were (and still are) used for its I-5 connection.
  When I, as an 11-year-old kid, first saw that they were using the original Riverside Drive ramps as a connection to and from I-5 to the southward (then) Pasadena Freeway, my reaction was the kid's version of WTF?  I always thought those ramps were substandard even as a street connector much less carrying the brunt of southbound I-5 traffic toward downtown L.A.!  But 55 years later, it's still there (although having been repaved and restriped countless times).  I'm guessing that tearing out the cliff to cobble together a set of high-speed ramps was a non-starter, considering the land was a city park (the 2nd largest in L.A. after Griffith, slightly to the north).  Adding flyovers to the Pasadena Freeway twin bridges over the L.A. river was probably dismissed as well due to the configuration of those bridges.  Likely the Division of Highways did what it could with the cards it was dealt -- although in reality the hand was dealt by the Division itself 20-25 years previously when the Arroyo Seco Parkway was in the planning stages.  At that time the proposed L.A. freeway system was largely radial in nature, centering on downtown; the Interstate loops weren't even a pipedream in the mid-30's. 

You could totally fix that old Riverside Drive set of ramps if you built a flyover on the right-hand side (south) of the 110 north for the traffic going to the 5 north and removed that left-hand exit that uses the lower part of old Riverside.  Then the footprint from the old northbound-to-northbound lanes could be regraded to make the 5 south to 110 south ramp wider, include shoulders, and have better turning radii where it finally connects to the 110 south.
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sparker

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Re: California
« Reply #95 on: August 26, 2016, 09:41:29 PM »

You could totally fix that old Riverside Drive set of ramps if you built a flyover on the right-hand side (south) of the 110 north for the traffic going to the 5 north and removed that left-hand exit that uses the lower part of old Riverside.  Then the footprint from the old northbound-to-northbound lanes could be regraded to make the 5 south to 110 south ramp wider, include shoulders, and have better turning radii where it finally connects to the 110 south.
Not quite -- NB 110 is coming out of a 4-lane-wide tunnel at that point, with the left lane dedicated to the turn to NB 5, and the 2nd lane splitting between the NB 5 ramp and the NB 110 main line.  It segues directly onto the L.A. river bridge at that point; this is the original bridge constructed when the tunnels contained North Figueroa St., and were re-purposed for NB only when the SB lanes of the Arroyo Seco Parkway were constructed.  Underneath the bridges are not only the L.A. River but several sets of railroad tracks; the Metrolink main service facility is directly north of the I-5 bridge, less than a half-mile to the northeast.  There's just no room left for any sort of viable flyover, absent a complete reconstruction of the 1938 original bridge -- which is a concrete multiple arch with ornate railings and superstructure details -- and is below the grade of the adjacent southbound bridge, which would also have to be bridged by any flyover!  Any such "modern" ramp facility would have had to be implemented in the late '50's and early '60's when I-5 was originally constructed.   
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sdmichael

Re: California
« Reply #96 on: August 27, 2016, 12:35:13 AM »

Not quite -- NB 110 is coming out of a 4-lane-wide tunnel at that point, with the left lane dedicated to the turn to NB 5, and the 2nd lane splitting between the NB 5 ramp and the NB 110 main line.  It segues directly onto the L.A. river bridge at that point; this is the original bridge constructed when the tunnels contained North Figueroa St., and were re-purposed for NB only when the SB lanes of the Arroyo Seco Parkway were constructed.  Underneath the bridges are not only the L.A. River but several sets of railroad tracks; the Metrolink main service facility is directly north of the I-5 bridge, less than a half-mile to the northeast.  There's just no room left for any sort of viable flyover, absent a complete reconstruction of the 1938 original bridge -- which is a concrete multiple arch with ornate railings and superstructure details -- and is below the grade of the adjacent southbound bridge, which would also have to be bridged by any flyover!  Any such "modern" ramp facility would have had to be implemented in the late '50's and early '60's when I-5 was originally constructed.

Just to correct... the bridge in question - the NB State 110 bridge, is NOT a concrete multiple arch bridge. It is a steel girder bridge and from 1937 (minor correction there). You also have the SB bridge, also steel girder (Bethlehem Steel at that) which is higher than the NB bridge. To do anything more than what is there would require even the tunnel to have work done on it, hence why things remain as they are.
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sparker

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Re: California
« Reply #97 on: August 27, 2016, 03:20:59 AM »

Could have sworn the original NB bridge was an arch!  Do recall the SB bridge as conventional girder.  Guess the old memory isn't what it used to be  :pan: -- been a long time (probably 25+ years) since I've actually been at ground level in that area -- pretty much up on I-5 since then on the way to somewhere else.  My mention of the grade of NB 110 being lower than that of SB meant that the SB bridge was higher (it had to be to clear the NB 110>5 ramp!).  Not many options for upgrades there, considering the topology, the tunnel, and the RR tracks below. 

Come to think of it, I probably conflated the mistaken arches on the 110 crossing with the street bridges downstream.  Mea culpa!
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Occidental Tourist

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Re: California
« Reply #98 on: August 29, 2016, 06:36:59 PM »

Wouldn’t the riverbed be a perfect location for bridge bents?  There’s lots of places in the river and between roads, the Arroyo, and storm channels in the area for bridge bents.  Here’s just one roughed-out example of where you could place bridge bents that presumably conforms with Caltrans curve radii requirements for such a bridge.      



I would think your two biggest engineering issues would be 1) relocating the power lines and telephone lines, and 2) whether the downgrade on the new offramp from the bridge to Riverside Drive was too steep such that you had to lose the Riverside Drive offramp.

I’m not an engineer, but to my knowledge there’s nothing (other than historical preservation issues) that would stop being able to marry a seismically independent box girder bridge to the existing steel bridge.

The other thing to consider is that although the southbound lanes are higher than the northbound lanes coming out of the tunnel, by the time you get to the Avenue 19 overcrossing, both northbound and southbound lanes are dropping such that they are almost parallel in height.  Any new bridge structure coming off the northbound 110 would be rising at a slight grade from the tunnel eastward, and should be able to easily clear both sets of lanes of the 110 as it curves northward at that point.



      

It’s the drop down over the Golden State Freeway and into the current distributor road to the 5 North that concerns me.  You’d probably have to raise that road significantly in order to marry it to the new bridge connection with an acceptable enough downgrade coming off the bridge.  That in turn leaves you with a likely too steep of a drop in too short of a distance to Riverside Drive to keep that offramp.

   
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jeffe

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Re: California
« Reply #99 on: August 30, 2016, 09:18:43 PM »

That ramp alignment looks good!  It would also allow for the "kink" in the South I-5 to CA-110 connector ramp to be removed.  This ramp could also be widened to allow for a proper right shoulder and thus give better sight lines around the hill.

I would think your two biggest engineering issues would be 1) relocating the power lines and telephone lines, and 2) whether the downgrade on the new offramp from the bridge to Riverside Drive was too steep such that you had to lose the Riverside Drive offramp.

1) Many of the power lines in this area were placed underground as part of the new traffic circle being built at the Figueroa and San Fernando intersection.  There is that triple circuit transmission line, but the towers could be raised to provide enough clearance.

2) Yeah, the Riverside Drive ramp might be a bit steep, but the ramps could be pushed back to intersect Riverside at the Oros intersection if needed.

I’m not an engineer, but to my knowledge there’s nothing (other than historical preservation issues) that would stop being able to marry a seismically independent box girder bridge to the existing steel bridge.

Based on your diagram it looks like this ramp could actually split off at the earth embankment prior to the bridge.  Thus, the two bridges would be completely separate structures.

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There was a discussion about Freeway Entrance signs earlier in this thread.  Here's one in Oakland where it looks like there were issues with illegal U-turns.  The no U-turn sign should be an I-580 shield:
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