I'm not talking about lane changes where they restripe, or the rebuilding of the approach to a new geometry. But major substantial alterations.
Examples:
Murray Baker Bridge: a large section of the truss removed with a new section welded in to provide the new portal.
Bayonne Bridge: Entire new deck, Portal, and approach built at a higher elevation
Lions Gate Bridge: Entire new deck truss, went from a pony truss type layout to deck.
George Washington Bridge: Lower deck added years after construction finished.
The Ben Franklin Bridge had several changes. When first opened, there were 3 lanes in each direction with tracks for street cars in the *middle* of the bridge. A decade or so later, the tracks on the outside of the bridge were built and used for more typical train/subway service. Streetcar/subway platforms built within the piers have never been used. On the bridge deck itself, the former streetcar tracks were converted to travel lanes. Later on, the 8 travel lanes became 7 lanes, with a minor narrowing of the bridge, probably to create larger and stronger barriers along the outer lanes.
Of the 4 DRPA bridges, this is the only one with major functional changes. Minor *permanent* changes on the bridges themselves (thus, we're not talking toll plaza changes) includes a permanent barrier that was installed on the Betsy Ross Bridge. The Commodore Barry Bridge always had over-lane bridges used for signage and open/closed lane indicators that appeared to show the bridge was designed for 6 (narrow) lanes. However, since the day it opened it was always stripped for 5 lanes, with modifications made to the over-head structures to accommodate the indicators for 5 lanes. If any major alternations occurred, it would've been prior to the bridge being put into service.
The Auckland [N. Z.] Harbour Bridge, originally 4 lanes, was widened to 8 lanes by attaching box girder sections to the sides. These sections, made by a Japanese company, came to be nicknamed the Nippon Clip-ons (http://www.teara.govt.nz/en/photograph/23650/the-nippon-clip-ons).
one that is debatable, as it could be considered a brand new bridge on old piers. The Edison bridge on US9 in NJ. They removed the original girders, shortened the piers, and built a brand new span over the old piers.
Huey P. Long bridge in New Orleans was widened and expanded (with bigger piers) with larger tracks for cars. Here a photo showing the bridge before https://en.wikipedia.org/wiki/Huey_P._Long_Bridge_%28Jefferson_Parish%29#/media/File:USS_New_Orleans_under_Huey_P_Long_Bridge.jpg and after http://www.nola.com/business/index.ssf/2013/06/huey_p_long_bridge_expansion_o.html
Like this redneck special?
Quote from: SteveG1988 on February 22, 2015, 04:20:39 PM
To me this looks like one, an overpass that is also a cable stay bridge on the ends. It looks like they widened the road and just put the cable stay bits on to reuse the existing overpass.
http://bridgehunter.com/il/madison/fairmount-lane/
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fbridgehunter.com%2Fphotos%2F23%2F28%2F232889-L.jpg&hash=165375fec30a6fa436e0d0d1ee7cc09cd3d25f38)
Quote from: Brandon on February 23, 2015, 12:10:24 PM
That's on I-55/70 just west of I-255. Currently, it appears to be closed to traffic. I have no idea why IDOT District 8 decided to do the redneck thing instead of just replacing it outright when the I-255 ramps were added under it.
From I-55/70, looking west:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi837.photobucket.com%2Falbums%2Fzz298%2Fmidamcrossrds%2F100_4606_zps664fa69d.jpg&hash=2892946571b306c0b42f12fb4d149324baa8c689) (http://s837.photobucket.com/user/midamcrossrds/media/100_4606_zps664fa69d.jpg.html)
Quote from: Brandon on August 17, 2015, 01:29:16 PM
Like this redneck special?
Quote from: SteveG1988 on February 22, 2015, 04:20:39 PM
To me this looks like one, an overpass that is also a cable stay bridge on the ends. It looks like they widened the road and just put the cable stay bits on to reuse the existing overpass.
http://bridgehunter.com/il/madison/fairmount-lane/
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fbridgehunter.com%2Fphotos%2F23%2F28%2F232889-L.jpg&hash=165375fec30a6fa436e0d0d1ee7cc09cd3d25f38)
Quote from: Brandon on February 23, 2015, 12:10:24 PM
That's on I-55/70 just west of I-255. Currently, it appears to be closed to traffic. I have no idea why IDOT District 8 decided to do the redneck thing instead of just replacing it outright when the I-255 ramps were added under it.
From I-55/70, looking west:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi837.photobucket.com%2Falbums%2Fzz298%2Fmidamcrossrds%2F100_4606_zps664fa69d.jpg&hash=2892946571b306c0b42f12fb4d149324baa8c689) (http://s837.photobucket.com/user/midamcrossrds/media/100_4606_zps664fa69d.jpg.html)
Definitely counts.
A debatable one. US1 over the Delaware River, new lanes built on extended pier caps.
A Future one.... I70's new bridge at St Louis.
One that doesn't fully count, I70 over the Missouri River. The Blanchette bridge is a brand new bridge on the original piers.
Quote from: SteveG1988 on August 17, 2015, 01:55:07 PM
A debatable one. US1 over the Delaware River, new lanes built on extended pier caps.
I'd give it some points. They had to remove some of the existing bridge support on each of the dozen or so piers - most of which are in the Delaware River - and slide a new wing in there on each side. And, they made it look nearly seamless to the previous look.
Quote from: jeffandnicole on August 17, 2015, 11:11:16 AM
The Ben Franklin Bridge had several changes. When first opened, there were 3 lanes in each direction with tracks for street cars in the *middle* of the bridge. A decade or so later, the tracks on the outside of the bridge were built and used for more typical train/subway service. Streetcar/subway platforms built within the piers have never been used. On the bridge deck itself, the former streetcar tracks were converted to travel lanes. Later on, the 8 travel lanes became 7 lanes, with a minor narrowing of the bridge, probably to create larger and stronger barriers along the outer lanes.
....
Similarly, the Brooklyn Bridge carried elevated trains and streetcars until 1950, when they stopped running, at which time the bridge was modified to carry six lanes of vehicular traffic.
Picture from 1907:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Ffineprintnyc.com%2Fimages%2Fblog%2Fold-new-york%2Fpart-3%2F1907-Brooklyn-Bridge-Train.jpeg&hash=f7a5c1db5fd331c3928a640c7a0ccd2a472a9ad0)
The Buckman Bridge(i295) in Jacksonville was originally dual spans. 2 lanes in each direction with no shoulders. In the late 1990s it was widened to 4 lanes in each direction with 4 lanes in each direction and full shoulders on each side. A new span was built immediately adjacent to the old and the ~1969 bridges were rehabbed. The old bridges made the 3.1 mile crossing seem like forever.
Many of Seattle's bridges had their streetcar tracks removed by 1941, with the notable exception of the Aurora Bridge (which never had them).
The Homer M. Hadley Memorial Bridge (the westbound I-90 floating bridge between Seattle and Mercer Island) will have its express lanes replaced by light rail by 2023.
The San Francisco-Oakland Bay Bridge originally had six lanes for cars on the top deck (3 each way), and on the bottom were two interurban rail tracks and three lanes for trucks and buses (1 each way and 1 reversible). Tracks removed, converted into five lanes on each deck, trucks and buses mixed with cars.
Quote from: kkt on August 18, 2015, 12:15:18 AM
The San Francisco-Oakland Bay Bridge originally had six lanes for cars on the top deck (3 each way), and on the bottom were two interurban rail tracks and three lanes for trucks and buses (1 each way and 1 reversible). Tracks removed, converted into five lanes on each deck, trucks and buses mixed with cars.
and the roadway in the tunnel lowered to allow for upper deck clearance.
I have heard that the Whitestone Bridge had its stiffening trusses added in response to the Tacoma Narrows Bridge collapse. They were removed in the bridge's last major overhaul.
Quote from: Pete from Boston on August 18, 2015, 09:13:09 AM
I have heard that the Whitestone Bridge had its stiffening trusses added in response to the Tacoma Narrows Bridge collapse. They were removed in the bridge's last major overhaul.
The Golden Gate Bridge also had additional stiffening added after the Tacoma Narrows collapse. Later, the GGB's concrete original deck was replaced with steel with a layer of epoxy-asphalt over it.
Quote from: Pete from Boston on August 18, 2015, 09:13:09 AM
I have heard that the Whitestone Bridge had its stiffening trusses added in response to the Tacoma Narrows Bridge collapse. They were removed in the bridge's last major overhaul.
Its sidewalks were also removed. I don't remember if any pedestrian facility was added in the recent rehab.
Quote from: Pete from Boston on August 18, 2015, 10:08:03 AM
Quote from: Pete from Boston on August 18, 2015, 09:13:09 AM
I have heard that the Whitestone Bridge had its stiffening trusses added in response to the Tacoma Narrows Bridge collapse. They were removed in the bridge's last major overhaul.
Its sidewalks were also removed. I don't remember if any pedestrian facility was added in the recent rehab.
NYC Roads tells us there were originally four lanes of traffic with sidewalks. I've never seen any photos of this configuration so I don't know what exactly the deal was. But I do know that the current suspension span has six lanes of traffic with no shoulders. There is no room for a walkway on the existing structure without reducing the number of lanes.
As far as I'm aware there are no plans to add a walkway by any means - the recent reconstruction of the approach roadways features wider lanes and shoulders, but no space for a walkway.
I take it you're not talking about doubling the spans, like the Blue Water or Sunshine Skyway Bridges (that one of course, replaced after the accident).
One that does count is the Houghton Lift Bridge. It originally had railroad tracks on the lower level. That level was paved for vehicle traffic, so in the summer the bridge can be stopped somewhat lifted so the lower level of the bridge meets the road level on land. Then more boats can fit under it without lifting. In the winter, with no boat traffic, the bridge is lowered fully down, and the lower deck is used by snowmobiles.
What about High Bridge, the oldest standing bridge in NYC, which had a number of its stone arches removed and replaced by a single steel arch? (And which recently reopened to foot traffic after some 40 years of closure.)
iPhone
Quote from: empirestate on August 18, 2015, 09:46:58 PM
What about High Bridge, the oldest standing bridge in NYC, which had a number of its stone arches removed and replaced by a single steel arch? (And which recently reopened to foot traffic after some 40 years of closure.)
Good one! I had pondered the various Harlem River swing bridges that have had new swing spans floated in but decided they were replacements more than alterations, forgetting this obvious example upstream.
Quote from: 1995hoo on August 17, 2015, 02:12:03 PM
Quote from: jeffandnicole on August 17, 2015, 11:11:16 AM
The Ben Franklin Bridge had several changes. When first opened, there were 3 lanes in each direction with tracks for street cars in the *middle* of the bridge. A decade or so later, the tracks on the outside of the bridge were built and used for more typical train/subway service. Streetcar/subway platforms built within the piers have never been used. On the bridge deck itself, the former streetcar tracks were converted to travel lanes. Later on, the 8 travel lanes became 7 lanes, with a minor narrowing of the bridge, probably to create larger and stronger barriers along the outer lanes.
....
Similarly, the Brooklyn Bridge carried elevated trains and streetcars until 1950, when they stopped running, at which time the bridge was modified to carry six lanes of vehicular traffic.
Picture from 1907:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Ffineprintnyc.com%2Fimages%2Fblog%2Fold-new-york%2Fpart-3%2F1907-Brooklyn-Bridge-Train.jpeg&hash=f7a5c1db5fd331c3928a640c7a0ccd2a472a9ad0)
Moreover, the Brooklyn Bridge was extensively rehabbed in 1948 under the guidance of David Steinman, but at this point I no longer remember what changes were made, only that others have noted they were significant. Others can probably better elaborate.
Interesting thread idea, by the way.
The Brooklyn Bridge was actually modified twice. First to remove the streetcar tracks and make room for four lanes of traffic (1944), and then again to remove the el tracks and make room for six lanes (1950).
This pales next to the Queensboro Bridge, though, which has had its configuration modified way too many times to count. Let's see...
The upper level originally contained just a pair of walkways. It later contained a pair of subway tracks in addition to the pair of walkways. Then the walkways were replaced with lanes of traffic, requiring the construction of new approach roadways. Then the train tracks were also replaced with lanes of traffic, resulting in further additional approach roadways.
The inner part of the lower level originally had a pair of trolley tracks plus room for vehicles, the tracks were later removed to allow four lanes of traffic. The outer part of the lower level was originally a pair of trolley tracks, the southern one is now an extra separate lane of eastbound traffic, the northern one is mostly a ped/bike walkway although part of it is now a single lane offramp from the westbound lanes.
In addition to all this there was for a while an elevator in the middle of the bridge which carried both pedestrians and vehicles (!) from the bridge down to what was then known as Welfare Island. When the Roosevelt Island Bridge was completed this elevator was abandoned and later demolished.
In terms of one that has a major alteration currently in progress, the Bayonne Bridge (NY 440/NJ 440) is currently being raised so that taller ships can pass under it.
Quote from: Duke87 on August 18, 2015, 06:09:31 PM
Quote from: Pete from Boston on August 18, 2015, 10:08:03 AM
Quote from: Pete from Boston on August 18, 2015, 09:13:09 AM
I have heard that the Whitestone Bridge had its stiffening trusses added in response to the Tacoma Narrows Bridge collapse. They were removed in the bridge's last major overhaul.
Its sidewalks were also removed. I don't remember if any pedestrian facility was added in the recent rehab.
NYC Roads tells us there were originally four lanes of traffic with sidewalks. I've never seen any photos of this configuration so I don't know what exactly the deal was.
If I'm not mistaken, there is a photo of this in Nathan Silver's
Lost New York, but I don't own it and the relevant page is not included in the Google Books preview.
The Duluth Transporter bridge. converted from a transporter type to a traditional lift bridge.
For non road, The Delair bridge in NJ, converted (still in place just imobilized) from swing to a lift span in 1959.
Pre 1959
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.workshopoftheworld.com%2Frichmond_bridesburg%2Fdelair_files%2Fpage68_1.jpg&hash=e83ff4981c0ca55ea12eb572eb72c4790a526933)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.sjrail.com%2Fwiki%2Fimages%2Farchive%2F2%2F28%2F20090804230926%21Delair_Bridge_-_PC.JPG&hash=604c31859d0626271a44e2df5e3297bd03927881)
Mid conversion
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fsjrail.com%2Fwiki%2Fimages%2F3%2F39%2FDelair_Bridge_a60.JPG&hash=3606cbc1d7b2bb54fb9593d1b1b85f41274cedad)
Now
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fshaun.zenfolio.com%2Fimg%2Fs%2Fv-3%2Fp266225030-3.jpg&hash=b90316b81112be97e48fa54fb8de0a9fa8ec04c1)
Also the Interstate bridge in WA.
How much of the original truss bridge was kept when they added the hump?
The toll booths on the original Hiway 30 bridge over the Missouri River at Blair Nebraska were midspan and cantilevered out from the bridge structure. Weren't too many people that liked stopping in the middle of the bridge with the metal grate decking and were happy to see them removed.
The existing 2 way bridge over the Missouri connecting Florence/Omaha to Crescent, Iowa was incorporated into I-680 as the eastbound structure. It was redecked to make the lanes as wide as possible within the existing steel frame. I think the railings were redone in a thinner concrete design than the existing metal ones. The bridge is still narrow for an Interstate bridge.
I don't know if the south bound I-29 bridge over the Big Sioux River just north of Sioux City was modified or replaced after the northbound structure collapsed just a few months after opening. I guess if it was ripped out and totally rebuilt after just a few months service that would be an extreme case for the topic.
The Maurice J. Tobin Mystic River Bridge had its west end, a former "Y" setup merging its upper and lower decks with those of I-93, rebuilt as a descending viaduct into a tunnel and connecting up to surface streets and an enormous helix on the other side of 93.
It also has had the toll booths mounted up on the bridge removed.
Clay's Ferry bridge in KY, twin span converted into one massive connected span.
http://bridgehunter.com/ky/fayette/clays-ferry/
Edit:
Did some research, i am 95% in agreement that they are brand new spans on the original piers with a central pier added in the 90s. Looking at old photos, the trusses had oval holes in the beams, the bridge lacks any oval holes in 2015.
Quote from: SteveG1988 on September 01, 2015, 09:26:38 PM
Clay's Ferry bridge in KY, twin span converted into one massive connected span.
http://bridgehunter.com/ky/fayette/clays-ferry/
Edit:
Did some research, i am 95% in agreement that they are brand new spans on the original piers with a central pier added in the 90s. Looking at old photos, the trusses had oval holes in the beams, the bridge lacks any oval holes in 2015.
And reading the report, I don't like erroneous information put in it. I am looking at the deck width listed at 60'. With 6 full lanes and shoulders that look like standard width, the real width is a little over 100'. And the incorrect width imputed is giving it an artificially low sufficiency rating and moreso, gives it a bad label of "functionally obsolete".
Quote from: Big John on September 01, 2015, 09:40:07 PM
Quote from: SteveG1988 on September 01, 2015, 09:26:38 PM
Clay's Ferry bridge in KY, twin span converted into one massive connected span.
http://bridgehunter.com/ky/fayette/clays-ferry/
Edit:
Did some research, i am 95% in agreement that they are brand new spans on the original piers with a central pier added in the 90s. Looking at old photos, the trusses had oval holes in the beams, the bridge lacks any oval holes in 2015.
And reading the report, I don't like erroneous information put in it. I am looking at the deck width listed at 60'. With 6 full lanes and shoulders that look like standard width, the real width is a little over 100'. And the incorrect width imputed is giving it an artificially low sufficiency rating and moreso, gives it a bad label of "functionally obsolete".
It's like nobody is quite sure what the heck it is. But it is a neat conversion anyway, as the new spans are actually variants on what was there before, probably for weight purposes.
This was the "Father Baker Bridge" in Lackawanna, NY.
(https://c1.staticflickr.com/9/8489/8171135477_11a3d9400f.jpg)
It's a mythical bridge, and has since been replaced by this:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F2gCeWOO.jpg&hash=8f0f590ca9494e4315b6c36926f63ef4ca7323dd)
Quote from: Buffaboy on September 29, 2015, 11:12:04 AM
This was the "Father Baker Bridge" in Lackawanna, NY.
(https://c1.staticflickr.com/9/8489/8171135477_11a3d9400f.jpg)
It's a mythical bridge, and has since been replaced by this:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F2gCeWOO.jpg&hash=8f0f590ca9494e4315b6c36926f63ef4ca7323dd)
I'm pretty sure that's just a whole new bridge.
Check out this Frankenstein bridge over the Wailua River on the island of Kauai.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi113.photobucket.com%2Falbums%2Fn208%2Ftriplemultiplex%2FHawaii%2FIMG_0642_zpstu4hb8jk.jpg&hash=620eccfd13b68725f125a709c77e1837a504eac2)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi113.photobucket.com%2Falbums%2Fn208%2Ftriplemultiplex%2FHawaii%2FIMG_0637_zpsixxytab0.jpg&hash=71e3828be68f5e50a1706677ecf6a32446259c73)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi113.photobucket.com%2Falbums%2Fn208%2Ftriplemultiplex%2FHawaii%2FIMG_0638_zpsajxb9wt7.jpg&hash=225591fd7ea58de5f581c4a330a35b6793564f94)
It's an old narrow-gauge railroad bridge with a two lane road bridge piggy backed on top of it. It carries the NB lanes of SR 56.
You might also notice an old abutment for a narrow road bridge between the two existing bridges. Seems to be the bridge that the piggybacked one replaced.
The Silliman Evans Bridge in Nashville, TN. Originally built in the early 60's to carry I-65 over the Cumberland River (near the current Nissan Stadium), then later I-24 was added after its NW extension finally fully opened around 1980, now it carries only I-24, as I-65 was rerouted around the west side of the Nashville loop along I-40 and former I-265 in 2000.
I don't have a lot of concrete info to back this up, but I believe the original layout was (2) 3-lane spans with little to no shoulders. Sometime in the mid-late 70's (based on the bridge parapets before they were upgraded within the past 10 years), the spans were widened to four lanes each with full shoulders, which also coincided with adding additional lanes to the I-40 interchange immediately east (literally south) of the bridge. The spans were widened by welding/attaching wing spans to the outside girders. There are four continuous lanes on the eastbound span, but it's worth noting that the westbound span has the leftmost lane drop somewhere in the middle while simultaneously creating an exit-only lane on the right for the Shelby Ave/Gateway Blvd exit.
This GSV link takes you to Davidson St underneath the bridge:
https://www.google.com/maps/@36.1610329,-86.7603819,3a,37.5y,181.02h,90.11t/data=!3m6!1e1!3m4!1svfsM4Xmx4zo4U2ARQzxkFA!2e0!7i13312!8i6656!6m1!1e1
On the portions of the bridge that cross land, it simply has standard beams added to the sides with additions made to the piers. It's hard to see if you zoom in, but the piers over the river itself appear to be narrower, which should be their original width.
Looks like Google hit up this area after a recent rehab, as everything appears freshly painted/texture-coated.
Another one in Nashville is the I-440 EB flyover ramp to I-24 WB, also connecting to I-40 EB and WB:
https://www.google.com/maps/place/Nashville,+TN/@36.126724,-86.7277886,3a,75y,300.57h,90.57t/data=!3m7!1e1!3m5!1sTmSA9keUsQto7P3N11330A!2e0!6s%2F%2Fgeo2.ggpht.com%2Fcbk%3Fpanoid%3DTmSA9keUsQto7P3N11330A%26output%3Dthumbnail%26cb_client%3Dsearch.TACTILE.gps%26thumb%3D2%26w%3D96%26h%3D64%26yaw%3D176.88503%26pitch%3D0!7i13312!8i6656!4m2!3m1!1s0x8864ec3213eb903d:0x7d3fb9d0a1e9daa0!6m1!1e1
Originally opened in 1986 as a single lane flyover, this one quickly caused serious afternoon rush hour backups throughout the late 80's and most of the 90's. I believe by 1997 or 1998, it was finally widened to two lanes by adding a girder to the outside of each "tub" and widening the deck accordingly, which was not easy.
This "tub" bridge style (not sure what the correct term for this is) is in use at all (3) of I-440's interstate interchanges (the I-24 interchange is painted red, the I-65 symmetrical stack is yellow, and the I-40 interchange is brown), plus the flyover on-ramp at I-40 Exit 216A coming from the BNA terminal has one of these bridges painted brown, and the I-40 EB ramp to I-640 WB in East Knoxville has one of these bridges painted blue. Does anybody know the correct term for this style of bridge, and have examples from other states?
Quote from: triplemultiplex on September 29, 2015, 04:07:34 PM
Check out this Frankenstein bridge over the Wailua River on the island of Kauai.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi113.photobucket.com%2Falbums%2Fn208%2Ftriplemultiplex%2FHawaii%2FIMG_0642_zpstu4hb8jk.jpg&hash=620eccfd13b68725f125a709c77e1837a504eac2)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi113.photobucket.com%2Falbums%2Fn208%2Ftriplemultiplex%2FHawaii%2FIMG_0637_zpsixxytab0.jpg&hash=71e3828be68f5e50a1706677ecf6a32446259c73)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi113.photobucket.com%2Falbums%2Fn208%2Ftriplemultiplex%2FHawaii%2FIMG_0638_zpsajxb9wt7.jpg&hash=225591fd7ea58de5f581c4a330a35b6793564f94)
It's an old narrow-gauge railroad bridge with a two lane road bridge piggy backed on top of it. It carries the NB lanes of SR 56.
You might also notice an old abutment for a narrow road bridge between the two existing bridges. Seems to be the bridge that the piggybacked one replaced.
Sort of like the Bahia Honda bridge in the Florida keys.. The road was built on top of the trusses for the railroad bridge. I am having trouble attaching images in tapatalk app.. Look up images pretty cool
Lower deck was added to the George Washington suspension bridge.
Some/most/all the bridges over the Cape Cod canal were raised.
Meridian Bridge had lift span mechanism removed, and upper level 2 way was made one way when lower level train tracks were removed and made into one way the other way for vehicles
I believe the original Aksarben Bridge was 2 lanes and was doubled to 4
Similarly, I think the original Sioux City to South Sioux City Bridge had additional lanes cantilevered out from the existing 2 lane bridge. I went over it as a kid, it must have been a scary thing, a 4 lane bridge, but with the 2 lanes in each direction divided by the steel structure, and the 2 opposing inside lanes had no divider. Probably a very unusual arrangement.
Don't know if this counts per the topic but the Decatur Nebraska Missouri River Bridge was originally built in a corn field, and then several years later had the river rerouted beneath it. (bridge was useless before the river was moved, took an act of Congress which is the why of the delay)
Does Key Bridge between Georgetown and Rosslyn count? Built as 4 lanes with sidewalks on each side; converted to 6 lanes with both sidewalks cantilevered.
Quote from: davewiecking on October 01, 2015, 02:03:35 AM
Does Key Bridge between Georgetown and Rosslyn count? Built as 4 lanes with sidewalks on each side; converted to 6 lanes with both sidewalks cantilevered.
Debatable, was there a massive structural change, or just the sidewalk change?
https://en.wikipedia.org/wiki/Old_Trails_Bridge
Topock bridge, converted to a pipeline bridge once I40 was completed.
Quote from: SteveG1988 on October 01, 2015, 05:45:31 AM
Quote from: davewiecking on October 01, 2015, 02:03:35 AM
Does Key Bridge between Georgetown and Rosslyn count? Built as 4 lanes with sidewalks on each side; converted to 6 lanes with both sidewalks cantilevered.
Debatable, was there a massive structural change, or just the sidewalk change?
The iconic (to use an overused word) supporting arches were unchanged. I believe half the roadbed was torn up, and then replaced with a unitary reinforced (larger) slab. Then ditto on the other half. So I guess the answer is "no"...
Quote from: jwolfer on September 30, 2015, 11:41:38 PM
Sort of like the Bahia Honda bridge in the Florida keys.. The road was built on top of the trusses for the railroad bridge. I am having trouble attaching images in tapatalk app.. Look up images pretty cool
I thought of that too. This Hawaii one is an exaggerated version of that conversion since the existing bridge was so narrow. Two bicycles would have trouble passing each other on the old narrow gauge bridge.
Chicago skyway had all of the approach piers replaced. I think they were steel before, and are concrete now.
I'd say the Bay Bridge between San Francisco and Oakland.
And a major alteration to put it mildly: the infamous Embarcadero!
Quote from: cappicard on January 05, 2016, 03:23:06 PM
I'd say the Bay Bridge between San Francisco and Oakland.
Yes: https://www.aaroads.com/forum/index.php?topic=16239.msg2087141#msg2087141
Quote
And a major alteration to put it mildly: the infamous Embarcadero!
Alterations, not destruction. And that's a viaduct, not a bridge.