Realignment vs Reconstruction.

[XamotCGC]

This might be a dumb question but I'm just wondering what kind of situations is  a realignment of a major highway considered over reconstruction?

[Scott5114]

Usually a realignment is done to eliminate unnecessary curves from a road. Older roadbuilding techniques tended to have more curves to follow the land as it was before the road went in, and it didn't matter so much because cars weren't as fast and there wasn't a general expectation that a driver would be able to maintain 65 mph between cities. As time went on, road building techniques and equipment improved, making it possible to build roads that were straighter and more level than before. Generally, when you had a realignment, the older road's geometry was bad enough that it was easier to abandon the old road and build a newer one with new technology.

After about the 1970s, roadbuilding knowledge reached more or less its modern form. Roads from that era and newer mostly have good bones, so when they need improvements, it is easier to upgrade them in place. Additionally, around that time environmental impact reviews started to be conducted on construction projects, so engineers needed a better justification for the greater environmental impact of tearing up new land for a new roadbed instead of just upgrading in place.

You now mostly see realignments happening when the old roadbed needs to be upgraded beyond what space and adjoining land use will allow. If you're upgrading a route to a freeway that runs through a town, upgrading in place is going to be complicated and expensive, since you have to demolish buildings, buy out access rights, etc. It's going to be much cheaper and less disruptive to realign the highway to a bypass around the outskirts of town. The old route then becomes a business route or turned over to the city as a local road.

[Bruce]

In situations where it's harder to reconstruct in place without massive disruption, a realignment (even to a less straight path) is usually the way to go.

An example: the SR 520 Floating Bridge's replacement in Seattle was constructed parallel to the old bridge, which luckily had a bend that made the new bridge a straighter shot.

[Crown Victoria]

Usually a realignment is done to eliminate unnecessary curves from a road. Older roadbuilding techniques tended to have more curves to follow the land as it was before the road went in, and it didn't matter so much because cars weren't as fast and there wasn't a general expectation that a driver would be able to maintain 65 mph between cities. As time went on, road building techniques and equipment improved, making it possible to build roads that were straighter and more level than before. Generally, when you had a realignment, the older road's geometry was bad enough that it was easier to abandon the old road and build a newer one with new technology.

After about the 1970s, roadbuilding knowledge reached more or less its modern form. Roads from that era and newer mostly have good bones, so when they need improvements, it is easier to upgrade them in place. Additionally, around that time environmental impact reviews started to be conducted on construction projects, so engineers needed a better justification for the greater environmental impact of tearing up new land for a new roadbed instead of just upgrading in place.

You now mostly see realignments happening when the old roadbed needs to be upgraded beyond what space and adjoining land use will allow. If you're upgrading a route to a freeway that runs through a town, upgrading in place is going to be complicated and expensive, since you have to demolish buildings, buy out access rights, etc. It's going to be much cheaper and less disruptive to realign the highway to a bypass around the outskirts of town. The old route then becomes a business route or turned over to the city as a local road.

Some good examples of realignments can be found on the Pennsylvania Turnpike.

Currently, reconstruction is in progress from approx. MP 102-109, west of Somerset. This particular stretch tends to have a lot of curves, so this particular project features two minor realignments to bring some of those curves up to modern standards.
https://www.google.com/maps/@40.0633899,-79.1161563,13z?hl=en  https://www.patpconstruction.com/mp102to109/default.aspx

The west end of the MP 102-109 project ties into the realignment done during the 1960s to bypass the Laurel Hill Tunnel. This was done in lieu of twinning that tunnel; it was considered more economical to bypass the tunnel in this case. Similarly, the Turnpike was realigned from the Breezewood interchange to approx. MP 174 around the same time to bypass the Rays Hill and Sideling Hill Tunnels, creating what we now know as the Abandoned Pennsylvania Turnpike. https://www.google.com/maps/@40.0169144,-78.1660496,13066m/data=!3m1!1e3?hl=en   https://www.google.com/maps/@40.0996973,-79.2120631,3880m/data=!3m1!1e3?hl=en



Besides the PA Turnpike, another good realignment example would be I-85 around Spartanburg, SC, done during the early to mid 1990s (the old alignment is now I-85 Business), as it was deemed easier to reroute I-85 (which needed major upgrades and widening) instead of reconstructing it.  https://www.google.com/maps/@34.987528,-81.9342144,13.21z?hl=en

[CtrlAltDel]

Another fun one is this short stretch of I-44 in Missouri, near exit 176, completed in around 2005:

[/ur]

[Revive 755]

^ The westbound lanes of I-44 were also realigned from that stretch to just west of the bridge over Little Piney Creek.  The 2002/2003 imagery in Google Earth shows the old alignment that was farther from the eastbound lanes with the current alignment under construction.

[CtrlAltDel]

^ The westbound lanes of I-44 were also realigned from that stretch to just west of the bridge over Little Piney Creek.  The 2002/2003 imagery in Google Earth shows the old alignment that was farther from the eastbound lanes with the current alignment under construction.

Weird. It explains, though, why the westbound direction has a full shoulder over the bridge, but the eastbound direction doesn't.

[Dirt Roads]

Besides the PA Turnpike, another good realignment example would be I-85 around Spartanburg, SC, done during the early to mid 1990s (the old alignment is now I-85 Business), as it was deemed easier to reroute I-85 (which needed major upgrades and widening) instead of reconstructing it.  https://www.google.com/maps/@34.987528,-81.9342144,13.21z?hl=en

You also have examples where the realignment was less expensive, but not implemented.  A recent example was the proposed realignment of I-81 around Abingdon, Virginia.  Instead, VDOT chose to upgrade all of the exits in the Abingdon area.

[Brian556]

Oklahoma has a ton of long stretches that were realigned, even when the old road was practically straight, and in some cases, had little to no development near it. Also, I've seen in some western states where they just built a new highway basically right next to the old one. Out there, nobody is really using the land for anything, and much of it could be federally-owned

[J N Winkler]

Oklahoma has a ton of long stretches that were realigned, even when the old road was practically straight, and in some cases, had little to no development near it. Also, I've seen in some western states where they just built a new highway basically right next to the old one. Out there, nobody is really using the land for anything, and much of it could be federally-owned

Especially in cases where it is desired to improve geometry, I suspect it often works out cheaper to build a closely parallel alignment rather than to attempt to reconstruct in place.

US 50 between Newton and Florence in Kansas is a case in point.  In the 1990's, it was essentially rebuilt in several sections, the cross-section was upgraded from asphalt without shoulders (ordinary two-lane) to concrete with full-width shoulders (Super Two), passing lanes were added, and Peabody was bypassed.  From memory, the sections were as follows:

*  Newton to Walton

*  Walton to Peabody

*  Peabody bypass

*  Peabody to Florence

Only the first section (Newton to Walton) was built on top of the existing roadbed, and in order to do that, KDOT had to institute a long-term detour via K-15 and an east-west paved Harvey County road, the latter being improved at KDOT's expense to accommodate the detour traffic.  For all of the other sections, workzone traffic was carried on the existing road.  The drainage upgrades were ambitious enough that in places a person driving past had to look up to see the top of the cribbing for the new concrete box culverts.

After the new road opened, the pavement on the old alignment was largely removed, with some sections being retained for aggregate storage.  However, it was largely not graded out of existence, nor were segments of unused right-of-way returned to the abutters.  I suspect KDOT prefers to retain the old right-of-way to maintain generous recovery area and avoid the expense of relocating pole-borne utilities, which were largely kept in place.

[tolbs17]

I think this part needs to be rebuilt and have a 65 or 70 mph design speed to reduce congestion due to the abnormal bridge replacement on Cold Springs Creek Road.

https://www.google.com/maps/dir/35.8785466,-83.1866727/35.6184476,-83.0096319/@35.6029105,-83.2437598,10.17z/data=!4m2!4m1!3e0

[wanderer2575]

Sometimes a realignment is done to save $$ even if it adds curves to a road.  For example, the recently completed LaPlaisance Road bridge over I-75 in Monroe County, MI.  The new bridge was built at less of an extreme angle to the freeway, so it is shorter and therefore was less expensive than a new bridge on the existing alignment would have been.

[fillup420]

I think this part needs to be rebuilt and have a 65 or 70 mph design speed to reduce congestion due to the abnormal bridge replacement on Cold Springs Creek Road.

https://www.google.com/maps/dir/35.8785466,-83.1866727/35.6184476,-83.0096319/@35.6029105,-83.2437598,10.17z/data=!4m2!4m1!3e0

Rebuilding that section of I-40 would be a massive undertaking. The original construction was challenging enough, as the area is prone to landslides.

[tolbs17]

I think this part needs to be rebuilt and have a 65 or 70 mph design speed to reduce congestion due to the abnormal bridge replacement on Cold Springs Creek Road.

https://www.google.com/maps/dir/35.8785466,-83.1866727/35.6184476,-83.0096319/@35.6029105,-83.2437598,10.17z/data=!4m2!4m1!3e0

Rebuilding that section of I-40 would be a massive undertaking. The original construction was challenging enough, as the area is prone to landslides.

Ah. Yeah. But if you compare it to I-26 in Mars Hill, that is not as curvy.

[wanderer2575]

Clearly what the world needs is FritzOwl laying out all the routes and then tolbs17 handling all the design and construction.

[TheHighwayMan3561]

When the final stretch of US 14 four-laning in southern Minnesota was completed recently, the last piece deviated from the existing alignment of US 14 by about a mile in some places. While I can't give any official explanation for this choice, it did eliminate one long curve near the MN 56 junctions. I think it also just allows a DOT to design something fresh that may be less constrained than a "Virginia twinning". Downside is having to acquire a lot more ROW.

[tolbs17]

This looks weird of how they left it instead of cleaning it up. The highway was reduced to 1 lane in each direction but the should clean this up.

I-85
https://maps.app.goo.gl/R4i4iRgQ9MWMrJES9

[US 89]

This looks weird of how they left it instead of cleaning it up. The highway was reduced to 1 lane in each direction but the should clean this up.

I-85
https://maps.app.goo.gl/R4i4iRgQ9MWMrJES9

Why? There could easily be more construction in the future that requires a traffic crossover there, so might as well leave the pavement.

Also, this 2.5-month bump has very little to do with the original topic of this thread.

[tolbs17]

This looks weird of how they left it instead of cleaning it up. The highway was reduced to 1 lane in each direction but the should clean this up.

I-85
https://maps.app.goo.gl/R4i4iRgQ9MWMrJES9

Why? There could easily be more construction in the future that requires a traffic crossover there, so might as well leave the pavement.

Also, this 2.5-month bump has very little to do with the original topic of this thread.

Because I feel like that would just be bad for the environment but I guess you're right for any future construction I guess it's the best to leave it there.

[Sapphuby]

Usually a realignment is done to eliminate unnecessary curves from a road. Older roadbuilding techniques tended to have more curves to follow the land as it was before the road went in, and it didn't matter so much because cars weren't as fast and there wasn't a general expectation that a driver would be able to maintain 65 mph between cities. As time went on, road building techniques and equipment improved, making it possible to build roads that were straighter and more level than before. Generally, when you had a realignment, the older road's geometry was bad enough that it was easier to abandon the old road and build a newer one with new technology.

After about the 1970s, roadbuilding knowledge reached more or less its modern form. Roads from that era and newer mostly have good bones, so when they need improvements, it is easier to upgrade them in place. Additionally, around that time environmental impact reviews started to be conducted on construction projects, so engineers needed a better justification for the greater environmental impact of tearing up new land for a new roadbed instead of just upgrading in place.

You now mostly see realignments happening when the old roadbed needs to be upgraded beyond what space and adjoining land use will allow. If you're upgrading a route to a freeway that runs through a town, upgrading in place is going to be complicated and expensive, since you have to demolish buildings, buy out access rights, etc. It's going to be much cheaper and less disruptive to realign the highway to a bypass around the outskirts of town. The old route then becomes a business route or turned over to the city as a local road.

You can find plenty of realignments all over U.S. 61 in northern Missouri. It's basically peppered with abandoned road realignments up there, with one section in particular having two realignments visible.

[Mapmikey]

This looks weird of how they left it instead of cleaning it up. The highway was reduced to 1 lane in each direction but the should clean this up.

I-85
https://maps.app.goo.gl/R4i4iRgQ9MWMrJES9

Why? There could easily be more construction in the future that requires a traffic crossover there, so might as well leave the pavement.

Also, this 2.5-month bump has very little to do with the original topic of this thread.

If you're going to complain about one...this one on I-95 near St Pauls NC has been left behind at least 25 years.  I want to say this was in use when I was going back and forth from Goose Creek SC to NOrfolk VA a bunch of times in 1994.

https://goo.gl/maps/Nz8ZvH1mhgjoZYG66

Presumably this will be taken care of by the I-95 widening in the near future but that was unlikely on anyone's mind in the mid 1990s.

[tolbs17]

This looks weird of how they left it instead of cleaning it up. The highway was reduced to 1 lane in each direction but the should clean this up.

I-85
https://maps.app.goo.gl/R4i4iRgQ9MWMrJES9

Why? There could easily be more construction in the future that requires a traffic crossover there, so might as well leave the pavement.

Also, this 2.5-month bump has very little to do with the original topic of this thread.

If you're going to complain about one...this one on I-95 near St Pauls NC has been left behind at least 25 years.  I want to say this was in use when I was going back and forth from Goose Creek SC to NOrfolk VA a bunch of times in 1994.

https://goo.gl/maps/Nz8ZvH1mhgjoZYG66

Presumably this will be taken care of by the I-95 widening in the near future but that was unlikely on anyone's mind in the mid 1990s.

Yes, I am aware of that being there, I just find it hilarious they don't clean stuff up.

[tolbs17]

When I-40 got a major face-lift in Southern Raleigh, I feel like they could have widened the part from. The Us-1/I-440 interchange  to lane wheeler road from 6 lanes to 8 lanes. There was certainly a lot of construction going on there and im not sure why they refused. Now its ultimately planned for 2025.