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[sprjus4]

The only relocation that would possibly make sense would be to make an I-55 bypass using the orphaned I-69 at Tunica, extended across the Mississippi to connect with I-40, and then connecting with I-55 again south of the I-555 terminus near Terrell. Problem with that is, what would you do with the current I-55 between I-269/relocated I-55 and downtown Memphis, or the current section of I-55? Unless you are willing to build out the I-69 extension from downtown Memphis to Dyersburg and the Union City bypass section, you have no real connection alternative to downtown Memphis other than I-40.

I’m confused… what exactly what would need to change with the existing I-55? It would remain in place… any new bypass would be a separate / alternate routing altogether.

[Rick Powell]

I don't think re-locating I-55 to another alignment is a realistic thing. Yes, it could be routed along an extension of the I-269 loop across the Mississippi River near Tunica. But the city of Memphis itself needs the two bridge crossings it has.

Agreed, and any "re-routing" of 55 will be a very minor shift, such as to accommodate a new bridge or twin span.

The current I-55 bridge sucks. It's just 4 lanes with zero shoulders at all. The bridge was completed in 1949; so it's getting up there in the years. I don't know if it's worth trying to rehabilitate the bridge versus starting over. The current trend with Interstate highway bridges over major rivers or navigation channels is building twin spans. The old Goethals Bridge (I-278) in Staten Island was a bit similar to the I-55 bridge, with just 4 lanes. Its replacement, two cable-stay bridges each have 3 lanes plus ample shoulders. And the North (Westbound) span has a barrier separated pedestrian/bike path. That's really the kind of thing needed at that I-55 bridge crossing.

The pedestrian path at I-55 is already there on the RR bridge, so no need to create an additional one. The current bridge is about 50 feet wide between the bridge rails including the concrete median. The existing framework could probably be salvaged and upgraded for another 50+ years of service, with a new deck in one direction with an additional span placed aside it similar to US 24 in Peoria IL. The existing bridge is just wide enough to fit 3 lanes, a full width right shoulder, and a teeny safety margin on the inside shoulder for one direction. But would still be an expensive proposition.

[bwana39]

I don't think re-locating I-55 to another alignment is a realistic thing. Yes, it could be routed along an extension of the I-269 loop across the Mississippi River near Tunica. But the city of Memphis itself needs the two bridge crossings it has.

Agreed, and any "re-routing" of 55 will be a very minor shift, such as to accommodate a new bridge or twin span.

The current I-55 bridge sucks. It's just 4 lanes with zero shoulders at all. The bridge was completed in 1949; so it's getting up there in the years. I don't know if it's worth trying to rehabilitate the bridge versus starting over. The current trend with Interstate highway bridges over major rivers or navigation channels is building twin spans. The old Goethals Bridge (I-278) in Staten Island was a bit similar to the I-55 bridge, with just 4 lanes. Its replacement, two cable-stay bridges each have 3 lanes plus ample shoulders. And the North (Westbound) span has a barrier separated pedestrian/bike path. That's really the kind of thing needed at that I-55 bridge crossing.

The pedestrian path at I-55 is already there on the RR bridge, so no need to create an additional one. The current bridge is about 50 feet wide between the bridge rails including the concrete median. The existing framework could probably be salvaged and upgraded for another 50+ years of service, with a new deck in one direction with an additional span placed aside it similar to US 24 in Peoria IL. The existing bridge is just wide enough to fit 3 lanes, a full width right shoulder, and a teeny safety margin on the inside shoulder for one direction. But would still be an expensive proposition.

There virtually assuredly will not be a "twin span" here... EVER. It is doubtful they would close it for 2-3 years to build a replacement span in the same place.   Nine months to redo the curve south was unacceptable.  The bottom line is what ever is to be done except for reconfiguring the southbound curve in I-55 will have to be done somewhere else.  The community is not going to tolerate giving up any more of the French Fort area. Just like I-40 through the park / zoo, it is not going to happen. Eventually I-55 will relocate and this bridge will be on a limited access link between I-55 and downtown Memphis.

It isn't like they are going to remove the Arkansas and Tennessee (Current I-55) bridge. The only issues with this bridge are capacity and earthquake resilience. Once (IF) I -55 moves, the capacity issue will be markedly lessened. The earthquake resilience issue is IF the big one hits, that it MIGHT partially or completely fail.  The simple fact is IF that happens, the damage to approaches and bridges across lesser bodies of water would be more likely to close the roads with no regard to the status of the A&T.

The primary reason the extended discussion of the earthquake damage to the existing bridge is more about the traffic that would be unable to transverse if it failed. This is an argument for a new bridge, but not necessarily removing this one when (if) it is bypassed.

I agree the northern Mississippi alternative SEEMS better to me, but there is a viable site extending from east of the BASF plant in West Memphis to around the Seacor site in Memphis tying in to the existing I-55 around South Parkway.  Expanding in place while feasible from a river and land perspective, from a cultural perspective, there is no willingness to allow any further expansion of the footprint here.  Expanding anything on the existing US-78 alignment (and to a lesser extent the southward I-55) is a no-go.

[abqtraveler]

I don't think re-locating I-55 to another alignment is a realistic thing. Yes, it could be routed along an extension of the I-269 loop across the Mississippi River near Tunica. But the city of Memphis itself needs the two bridge crossings it has.

Agreed, and any "re-routing" of 55 will be a very minor shift, such as to accommodate a new bridge or twin span.

The current I-55 bridge sucks. It's just 4 lanes with zero shoulders at all. The bridge was completed in 1949; so it's getting up there in the years. I don't know if it's worth trying to rehabilitate the bridge versus starting over. The current trend with Interstate highway bridges over major rivers or navigation channels is building twin spans. The old Goethals Bridge (I-278) in Staten Island was a bit similar to the I-55 bridge, with just 4 lanes. Its replacement, two cable-stay bridges each have 3 lanes plus ample shoulders. And the North (Westbound) span has a barrier separated pedestrian/bike path. That's really the kind of thing needed at that I-55 bridge crossing.

The pedestrian path at I-55 is already there on the RR bridge, so no need to create an additional one. The current bridge is about 50 feet wide between the bridge rails including the concrete median. The existing framework could probably be salvaged and upgraded for another 50+ years of service, with a new deck in one direction with an additional span placed aside it similar to US 24 in Peoria IL. The existing bridge is just wide enough to fit 3 lanes, a full width right shoulder, and a teeny safety margin on the inside shoulder for one direction. But would still be an expensive proposition.

There virtually assuredly will not be a "twin span" here... EVER. It is doubtful they would close it for 2-3 years to build a replacement span in the same place.   Nine months to redo the curve south was unacceptable.  The bottom line is what ever is to be done except for reconfiguring the southbound curve in I-55 will have to be done somewhere else.  The community is not going to tolerate giving up any more of the French Fort area. Just like I-40 through the park / zoo, it is not going to happen. Eventually I-55 will relocate and this bridge will be on a limited access link between I-55 and downtown Memphis.

Building a parallel span to the north of the existing I-55 bridge could theoretically be done, but doing so would require demolition of the Frisco Railroad Bridge and reconstructing it closer to the Harrihan Railroad Bridge (or demolishing both railroad bridges and building a wider 3-track railroad bridge in the footprint of the Harrihan Bridge). A parallel span for I-55 could then be built where the Frisco Bridge stands today.

While that would not disturb the historic parkland that sits immediately to the south of the current I-55 span, it would be a very costly solution, as TDOT and ArDOT would have to pay for the relocation/reconstruction of the railroad bridges in addition to building the new or parallel I-55 span. I would figure a project like that would end up costing over a billion dollars to complete.

[Rick Powell]

Building a parallel span to the north of the existing I-55 bridge could theoretically be done, but doing so would require demolition of the Frisco Railroad Bridge and reconstructing it closer to the Harrihan Railroad Bridge (or demolishing both railroad bridges and building a wider 3-track railroad bridge in the footprint of the Harrihan Bridge). A parallel span for I-55 could then be built where the Frisco Bridge stands today.

While that would not disturb the historic parkland that sits immediately to the south of the current I-55 span, it would be a very costly solution, as TDOT and ArDOT would have to pay for the relocation/reconstruction of the railroad bridges in addition to building the new or parallel I-55 span. I would figure a project like that would end up costing over a billion dollars to complete.

I dunno, I have been involved with several major river bridges that had about 10' clearance face to face with the existing bridge while under construction. I think a 60 foot deck could fit in the space that could carry temporary 2 way traffic while the old bridge was rehabbed. Would be interesting to see any of the conceptual preliminary engineering that has been done on this. Agree that the staging on this to get it back on alignment on the east end would be very tight and expensive.

[bwana39]

I don't think re-locating I-55 to another alignment is a realistic thing. Yes, it could be routed along an extension of the I-269 loop across the Mississippi River near Tunica. But the city of Memphis itself needs the two bridge crossings it has.

Agreed, and any "re-routing" of 55 will be a very minor shift, such as to accommodate a new bridge or twin span.

The current I-55 bridge sucks. It's just 4 lanes with zero shoulders at all. The bridge was completed in 1949; so it's getting up there in the years. I don't know if it's worth trying to rehabilitate the bridge versus starting over. The current trend with Interstate highway bridges over major rivers or navigation channels is building twin spans. The old Goethals Bridge (I-278) in Staten Island was a bit similar to the I-55 bridge, with just 4 lanes. Its replacement, two cable-stay bridges each have 3 lanes plus ample shoulders. And the North (Westbound) span has a barrier separated pedestrian/bike path. That's really the kind of thing needed at that I-55 bridge crossing.

The pedestrian path at I-55 is already there on the RR bridge, so no need to create an additional one. The current bridge is about 50 feet wide between the bridge rails including the concrete median. The existing framework could probably be salvaged and upgraded for another 50+ years of service, with a new deck in one direction with an additional span placed aside it similar to US 24 in Peoria IL. The existing bridge is just wide enough to fit 3 lanes, a full width right shoulder, and a teeny safety margin on the inside shoulder for one direction. But would still be an expensive proposition.

There virtually assuredly will not be a "twin span" here... EVER. It is doubtful they would close it for 2-3 years to build a replacement span in the same place.   Nine months to redo the curve south was unacceptable.  The bottom line is what ever is to be done except for reconfiguring the southbound curve in I-55 will have to be done somewhere else.  The community is not going to tolerate giving up any more of the French Fort area. Just like I-40 through the park / zoo, it is not going to happen. Eventually I-55 will relocate and this bridge will be on a limited access link between I-55 and downtown Memphis.

Building a parallel span to the north of the existing I-55 bridge could theoretically be done, but doing so would require demolition of the Frisco Railroad Bridge and reconstructing it closer to the Harrihan Railroad Bridge (or demolishing both railroad bridges and building a wider 3-track railroad bridge in the footprint of the Harrihan Bridge). A parallel span for I-55 could then be built where the Frisco Bridge stands today.

While that would not disturb the historic parkland that sits immediately to the south of the current I-55 span, it would be a very costly solution, as TDOT and ArDOT would have to pay for the relocation/reconstruction of the railroad bridges in addition to building the new or parallel I-55 span. I would figure a project like that would end up costing over a billion dollars to complete.

Who owns the railway bridges? If it is a railroad or a consortium of railroads, it becomes a huge competition over "what is in it for me?" It generally goes well beyond the bridge itself into closing grade crossings, allowing them to change, delete, or add routes.  Nobody has "it's mine" down like the rail lines.

Even beyond that, I think we are gravely underestimating the cost of both the highway bridge and the railroad bridges.  I figure at least $1.5B each.

[Plutonic Panda]

I’d say each bridge would at least be 1.5b each likely being closer to 2-3 billion each.

[vdeane]

Building a parallel span to the north of the existing I-55 bridge could theoretically be done, but doing so would require demolition of the Frisco Railroad Bridge and reconstructing it closer to the Harrihan Railroad Bridge (or demolishing both railroad bridges and building a wider 3-track railroad bridge in the footprint of the Harrihan Bridge). A parallel span for I-55 could then be built where the Frisco Bridge stands today.

While that would not disturb the historic parkland that sits immediately to the south of the current I-55 span, it would be a very costly solution, as TDOT and ArDOT would have to pay for the relocation/reconstruction of the railroad bridges in addition to building the new or parallel I-55 span. I would figure a project like that would end up costing over a billion dollars to complete.

I dunno, I have been involved with several major river bridges that had about 10' clearance face to face with the existing bridge while under construction. I think a 60 foot deck could fit in the space that could carry temporary 2 way traffic while the old bridge was rehabbed. Would be interesting to see any of the conceptual preliminary engineering that has been done on this. Agree that the staging on this to get it back on alignment on the east end would be very tight and expensive.

Yeah, there's definitely room for a 60' bridge with 40' on each side between the existing bridge and the rail bridge.  The only issue is that this path would need to be relocated and exit 12C would need to be closed.

[CtrlAltDel]

Another possibility might be to run the northbound lanes something like this:

[bwana39]

Another possibility might be to run the northbound lanes something like this:

Can you imagine what the Railroads would want for that? That is are least 6 tracks crossed.  It would probably cost 24 grade crossings (closed) and 10-15 million dollars.

[MikeTheActuary]

The "north of the railroad bridge" alignment would also face a LOT of opposition due to the impact on the Great River Crossing -- the ped/bikeway on the north side of the northernmost bridge.  Part of the attraction of that bridge is the views afforded from the crossing.

The fact that the TV station with the leading local newscast would have its broadcast studio taken for such an alignment probably also wouldn't help.

[bwana39]

The "north of the railroad bridge" alignment would also face a LOT of opposition due to the impact on the Great River Crossing -- the ped/bikeway on the north side of the northernmost bridge.  Part of the attraction of that bridge is the views afforded from the crossing.

The fact that the TV station with the leading local newscast would have its broadcast studio taken for such an alignment probably also wouldn't help.

I think expansion at this location while possible is neither a good choice or even politically viable.

I prefer a crossing in DeSoto County (MS), but there is a viable crossing point just a couple of miles to the south of the existing bridge that MOSTLY misses occupied properties and is south of the historic and tourist areas. It is on the radar of the states.

It has an advantage over the current bridge location as there will not be as severe a curve as will exist even after the new intersection / curve is built at I-55 /US-78.

[triplemultiplex]

A new bridge for 55 should go a little further south; kind of like this:

Note that I consider this draft outdated as I didn't think about the utility of retaining the existing span.  Been meaning to revisit, but the urge to play with fictional maps comes in waves.
In my head, the old span could be reconfigured into a 3 lane facility with a movable barrier that lets the bridge have two inbound lanes and one outbound lane in the morning and the reverse for the evening commute.

[CtrlAltDel]

The "north of the railroad bridge" alignment would also face a LOT of opposition due to the impact on the Great River Crossing -- the ped/bikeway on the north side of the northernmost bridge.  Part of the attraction of that bridge is the views afforded from the crossing.

The fact that the TV station with the leading local newscast would have its broadcast studio taken for such an alignment probably also wouldn't help.

Ah.

A new bridge for 55 should go a little further south; kind of like this:

This seems interesting, though. I can imagine that the cost would be pretty high since it's considerably longer, but still it's a good idea.

[bwana39]

The "north of the railroad bridge" alignment would also face a LOT of opposition due to the impact on the Great River Crossing -- the ped/bikeway on the north side of the northernmost bridge.  Part of the attraction of that bridge is the views afforded from the crossing.

The fact that the TV station with the leading local newscast would have its broadcast studio taken for such an alignment probably also wouldn't help.

Ah.

A new bridge for 55 should go a little further south; kind of like this:

This seems interesting, though. I can imagine that the cost would be pretty high since it's considerably longer, but still it's a good idea.

This is about what the Tennessee folks proposed . Between over-water and approaches, there won't be that much difference. While the approaches would be mostly slab bridges and main spans would probably be cable stayed, You are probably looking at 2 cable stayed spans even on the shorter distance where the existing bridge is.  So either place, probably two towers in the water.  The added over water distance will cost more, but the each tower is what really adds  expense.

[triplemultiplex]

In terms of span length, what matters is the width of the navigation channel. 
The total bridge length is going to be basically the same no matter where one places a new bridge around Memphis because while the channel width and the navigation channel width can vary, the floodplain width is functionally the same from Shelby Forest to the casinos.

[MikieTimT]

In terms of span length, what matters is the width of the navigation channel. 
The total bridge length is going to be basically the same no matter where one places a new bridge around Memphis because while the channel width and the navigation channel width can vary, the floodplain width is functionally the same from Shelby Forest to the casinos.

While that's true, the angle bridged between the levees on either side does have an impact on the length required to be bridged.  That's why DOTs try as hard as possible to cross perpendicular to the body of water.  The picture noted above would be certainly preferable to the status quo, but it would require more bridge length for sure.

[bwana39]

In terms of span length, what matters is the width of the navigation channel. 
The total bridge length is going to be basically the same no matter where one places a new bridge around Memphis because while the channel width and the navigation channel width can vary, the floodplain width is functionally the same from Shelby Forest to the casinos.

While that's true, the angle bridged between the levees on either side does have an impact on the length required to be bridged.  That's why DOTs try as hard as possible to cross perpendicular to the body of water.  The picture noted above would be certainly preferable to the status quo, but it would require more bridge length for sure.

I agree there is more span over the water. I still think it would be the same 2 pylons in the water that there would be at the existing site. I don't particularly see a significant additional distance in the complete bridge + approach bridges though.  My mind is boggled by the expense of any of it. When new construction of surface pavement is running in excess of $2M per lane mile, it is getting staggering.

[CtrlAltDel]

Work is ongoing, as seen in this pic from April 17.



Also, next weekend the bridge will be closed to set up a new traffic configuration.