I-40 in North Carolina

[Strider]

I think rebuilding on majority viaducts, similar to I-70 through the Rockies or the H3, might be better for long term resilience.

The Rockies are different in compared to the Appalachians. Interstate H-3 was one of the most expensive builds. That rerouting discussions should be moved to fictional highways as there has been no actual discussions related to that.

Besides, viaducts and tunnels isn't always the solution. A few years ago, I-70 viaduct in Glenwood Canyon was flooded due to excessive rain. That area is also prone to rock slides and flooding. Last year, I-H3 also flooded. How many discussions were there about rerouting these roads? Nothing.

Wyoming wanted to reroute I-80 between Rawlins and Laramie due to excessive wrecks along the current I-80 routing during Winter/Blizzard season (if I am correct, they close that section of I-80 during excessive winter weather), but didn't proceed with it because of it costs between $6 billion and $12 billion... and there's no money.

So sometimes keeping current routes is the best bet even if that means fixing it all over again.

[ElishaGOtis]

Would CA-1 near Big Sur be a good comparison to the situation on I-40, or. Is it like comparing apples to oranges given the extreme logistical challenges of reconstruction on CA-1?

[Strider]

Yeah, CA-1's situation in the Big Sur region is similar (but they get hit by rockslides, waves from the ocean very often). They're doing an emergency repair on the exact location part of the road that was damaged. They don't plan on moving CA-1 to another location.

[bwana39]

Yeah, CA-1's situation in the Big Sur region is similar (but they get hit by rockslides, waves from the ocean very often). They're doing an emergency repair on the exact location part of the road that was damaged. They don't plan on moving CA-1 to another location.

Yeah, but... The PCH is a tourist destination. I-40 is a freight highway.

[bwana39]

I think rebuilding on majority viaducts, similar to I-70 through the Rockies or the H3, might be better for long term resilience.

So sometimes keeping current routes is the best bet even if that means fixing it all over again.

This is not going to be a fix. It is going to be a start from scratch re-engineer and start over. The right answer MIGHT be to rebuild it in place.

They got one lane each way open temporarily then a repeat came up.  They as I understand are probably 18 months from having a plan to "fix" I-40 much less actually do the EXPENSIVE work it will take regardless of the method (and location) chosen.  (And I concede, that they appear to be invested in the current track through these canyons.)

[thenetwork]

The Rockies are different in compared to the Appalachians. Besides, viaducts and tunnels isn't always the solution. A few years ago, I-70 viaduct in Glenwood Canyon was flooded due to excessive rain. That area is also prone to rock slides and flooding. Last year, I-H3 also flooded. How many discussions were there about rerouting these roads? Nothing.

Actually there is increased talk about providing at least an all-weather alternate route for passenger vehicles via Cottonwood Pass. 

Currently, Cottonwood can only be used by smaller vehicles in the summer months. Outside of that, a Glenwood Canyon closure  results in a guaranteed 3+ hour detour via Craig and Steamboat Springs (on a GOOD day). 

[Beltway]

I-40 needed to have a segment between Knoxville TN and Asheville NC. There was no easy way to build that. Now that the segment has been in service for over 50 years, we need to think about what is needed for the next 50 years.
The Pigeon River alignment is not a good place for a highway, as we have seen.
I would suggest a 10- to 20-mile relocation out of that valley and onto higher ground on a straighter alignment. Like this one, and it would likely require two or three tunnels about a mile long each.

That is not going to happen for many reasons. Let it go.

I am not suggesting that it will happen in the near future -- just that it needs to have a location/EIS study for determining what to do in 2030 or 2035 and beyond.

The existing highway has had a series of major problems including another a week ago.  It is not suitable for a modern high-volume rural Interstate highway corridor.

[ElishaGOtis]

I-40 needed to have a segment between Knoxville TN and Asheville NC. There was no easy way to build that. Now that the segment has been in service for over 50 years, we need to think about what is needed for the next 50 years.
The Pigeon River alignment is not a good place for a highway, as we have seen.
I would suggest a 10- to 20-mile relocation out of that valley and onto higher ground on a straighter alignment. Like this one, and it would likely require two or three tunnels about a mile long each.

That is not going to happen for many reasons. Let it go.

I am not suggesting that it will happen in the near future -- just that it needs to have a location/EIS study for determining what to do in 2030 or 2035 and beyond.

The existing highway has had a series of major problems including another a week ago.  It is not suitable for a modern high-volume rural Interstate highway corridor.

Completely agree, especially if it gets busy enough to warrant 6 lanes of capacity, which NO WAY can fit in the current ROW...

[Beltway]

I am not suggesting that it will happen in the near future -- just that it needs to have a location/EIS study for determining what to do in 2030 or 2035 and beyond.
The existing highway has had a series of major problems including another a week ago.  It is not suitable for a modern high-volume rural Interstate highway corridor.

Completely agree, especially if it gets busy enough to warrant 6 lanes of capacity, which NO WAY can fit in the current ROW...

The Average Daily Traffic (ADT) on I-40 at the North Carolina–Tennessee border, particularly through the Pigeon River Gorge, typically ranges between 25,000 and 30,000 vehicles per day, depending on the exact location and year. Of that total, large trucks make up approximately 20% to 30% of the traffic volume.

Approaching 6-lane warrants.

The potential there is to shave a lot of miles off the route. One I can see would be a 7 mile long relocation that would replace 11 miles of highway.

A longer one I can see would be a 12 mile long relocation that would replace 18 miles of highway.

[Strider]

I-40 needed to have a segment between Knoxville TN and Asheville NC. There was no easy way to build that. Now that the segment has been in service for over 50 years, we need to think about what is needed for the next 50 years.
The Pigeon River alignment is not a good place for a highway, as we have seen.
I would suggest a 10- to 20-mile relocation out of that valley and onto higher ground on a straighter alignment. Like this one, and it would likely require two or three tunnels about a mile long each.

That is not going to happen for many reasons. Let it go.

I am not suggesting that it will happen in the near future -- just that it needs to have a location/EIS study for determining what to do in 2030 or 2035 and beyond.

The existing highway has had a series of major problems including another a week ago.  It is not suitable for a modern high-volume rural Interstate highway corridor.

Near the future or not, it's not going to happen. You can keep this conversation going if you want to. Until I hear anything from NCDOT about that, I'm done with this conversation.

[NE2]

(a) fictional.
(b) with the construction of I-74, there's now an all-freeway alternate that's only 11 miles longer. 6-laning 150 miles of I-81 would be so much more feasible and, with a higher speed limit, would take a bunch of long distance traffic off I-40. Google Maps even estimates the longer route being 7 minutes faster.
(c) suck it.

[Beltway]

(a) fictional.
(b) with the construction of I-74, there's now an all-freeway alternate that's only 11 miles longer. 6-laning 150 miles of I-81 would be so much more feasible and, with a higher speed limit, would take a bunch of long distance traffic off I-40. Google Maps even estimates the longer route being 7 minutes faster.
(c) suck it.

a) The critical problems of the current route are a reality and not fiction -- including a year or more of 2-lane 2-way traffic -- something that can repeat at any time -- this is a historical problem.

b) For some routings. Connecting Knoxville, Asheville, Charlotte and Spartanburg, for example are going to use I-40.

I-81 is busy with its own traffic needs and needs 6 lanes today -- these routes form a network that support all the regional needs -- Google is your friend -- I-40 has been part of the national network from the very beginning -- this is not an either-or situation.

c) If you are a current user of I-40 between Knoxville and Asheville, you are experiencing a lot of difficulty. It is not the 1960s anymore.

[ElishaGOtis]

There seems to be some political support for not rebuilding the highway where it currently is... I wouldn't completely dismiss this prospect. Look at one of the mountain sections of the A1 in Italy.

To clarify what I meant... https://maps.app.goo.gl/umnhEDbAxfA47J2s7?g_st=ic is this a valid project comparison or am I comparing apples to oranges here? There are several multi-mile tunnels along this corridor dealing with similar geological conditions (I think...). The old A1 corridor vs the new A1-Var corridor can be seen somewhat easily side-by-side. Granted, these are all tolled being in Italy but still...

[cowboy_wilhelm]

There will undoubtedly be a feasibility study after Helene. After all of the incidents that have occurred over the years and more than a billion dollars in repairs, someone is asking if we can fix this.

The feasibility study will provide multiple possible improvements and pros and cons. The costs for said improvements will be billions of dollars. The recommended alternative will be to continue to rebuild I-40 every time there is a rockslide or embankment failure. An engineer will confidently state that Helene was a once-in-a-millennium event that won't be repeated in our lifetimes and the costs for the alternatives are not warranted.

[Beltway]

There will undoubtedly be a feasibility study after Helene. After all of the incidents that have occurred over the years and more than a billion dollars in repairs, someone is asking if we can fix this.
The feasibility study will provide multiple possible improvements and pros and cons. The costs for said improvements will be billions of dollars. The recommended alternative will be to continue to rebuild I-40 every time there is a rockslide or embankment failure. An engineer will confidently state that Helene was a once-in-a-millennium event that won't be repeated in our lifetimes and the costs for the alternatives are not warranted.

Hurricane Camille (1969) and Tropical Storm Agnes (1972) are often described as "100-year storms" due to their extreme rarity and devastating impact.

Camille struck the Mississippi Gulf Coast as a Category 5 hurricane with sustained winds over 190 mph and a storm surge of 24 feet. It caused catastrophic damage and remains one of the most intense hurricanes to ever hit the U.S.

Agnes, though only a Category 1 hurricane, became infamous for its record-breaking inland flooding, especially in Pennsylvania, where rivers like the Susquehanna overflowed disastrously. It caused over $3 billion in damage and led to the retirement of the name "Agnes".

The term "100-year storm" doesn't mean it happens once every century—it refers to a 1% chance of occurring in any given year. Both storms exceeded expectations for their time and reshaped how the U.S. approached disaster preparedness and floodplain management.

Hurricane Camille (1969), though it made landfall on the Gulf Coast, caused devastating flash floods when its remnants swept into Virginia. In Nelson County, over 27 inches of rain fell in just a few hours, triggering landslides and wiping out entire communities. More than 100 people died in Virginia alone, and 133 bridges were destroyed.

Tropical Storm Agnes (1972) was even more widespread. Though downgraded from hurricane status, it dumped over a foot of rain across Maryland, Virginia, and Pennsylvania, after an already wet spring. The result? Record-breaking floods that overwhelmed rivers like the Potomac, James, and Susquehanna. In Maryland, the Patuxent River rose to 22.5 feet, submerging towns like Laurel. Across the region, 122 people died, and the storm caused what was then the costliest natural disaster in U.S. history.

These storms didn't just leave physical scars—they reshaped floodplain policy, emergency response, and even how we forecast inland storm impacts.

They were catastrophic across the Mid-Atlantic.

These storms didn't just leave physical scars—they reshaped floodplain policy, emergency response, and even how we forecast inland storm impacts.

The James River had historic floods -- James River has a long and dramatic history of flooding, especially near Richmond, Virginia. Two of the most catastrophic events were

Hurricane Agnes (1972): This storm caused the highest recorded flood on the James River at Richmond, cresting at 28.62 feet. It overwhelmed the city's infrastructure and remains the flood of record.

Hurricane Camille (1969): Though Camille made landfall on the Gulf Coast, its remnants dumped torrential rain in Virginia, pushing the James River to a crest of 24.95 feet—the second-highest on record.

These events reshaped floodplain management and led to the construction of levees, floodwalls, and better forecasting systems. The river's flood stage at Richmond is 12 feet, so these historic crests were truly extraordinary.

Agnes brought prolonged, soaking rains to the western NC region after an already wet spring. Rivers like the French Broad, Catawba, and Watauga swelled beyond their banks, causing widespread flooding in towns such as Asheville, Boone, and Hendersonville. Roads and bridges were washed out, and landslides isolated mountain communities. The storm's inland flooding was among the worst in the 20th century for the Mid-Atlantic and southern Appalachians.

These storms helped underscore the vulnerability of western NC's mountainous terrain to inland tropical rainfall, not just coastal wind and surge.