Constructing Freeway Tunnels

[The Ghostbuster]

Does anyone think there will be many freeway tunnels constructed in the future? And as a follow-up question, where would you like a tunnel to be constructed?

[Bickendan]

I'd like to see the Eastbank Freeway (I-5) buried under the Willamette and up to the Fremont Stack, as well as the Mt Hood Freeway built out to I-205.

Realistically, given the issues of the Big Dig and the Alaskan have and are dealing with, I imagine the US is going to avoid urban or long rural freeway tunnels at any cost. Certainly, the Big Dig and the Alaskan could theoretically impact any chance of the 710 gap from being built.

[Bruce]

The Alaskan Way Viaduct replacement debacle has show that it's smarter to split up freeway tunnels into two smaller tunnels instead of going all-in. I would've preferred the temporary mess of a demolished viaduct and cut-and-cover construction instead of waiting on Bertha.

I'd love to see I-5 in Downtown Seattle get lowered a bit further (with tunneling some segments where necessary) where possible and fully covered with a terraced park lid.

[peterj920]

The tunnels aren't very long, but in Milwaukee, WI, the Mitchell Interchange was reconstructed from a Directional T ramps to ramps with 3 tunnels.  I have a satellite overview of the interchange, and you can streetview to look inside the tunnels.  The interchange was reconstructed to have right exits only,( the old configuration had left exits) and tunnels were most likely chosen because there wasn't much room to construct flyover ramps from the right.  I really like this configuration and it will be interesting to see if other DOTs will follow this design in the future.

https://www.google.com/maps/@42.9622844,-87.9332208,653m/data=!3m1!1e3?hl=en

[cpzilliacus]

New freeway [motorway] tunnels in Sweden have been blasted and drilled out of rock under urban and suburban areas of Stockholm.

Norra länken

Södra länken

[Duke87]

Realistically, given the issues of the Big Dig and the Alaskan have and are dealing with, I imagine the US is going to avoid urban or long rural freeway tunnels at any cost. Certainly, the Big Dig and the Alaskan could theoretically impact any chance of the 710 gap from being built.

Also, American cities are not typically as space-constrained as cities on other continents are. Tunneling is expensive no matter what runs through it and is usually only the method of choice if building at or above ground level is impractical.

From the perspective of aesthetics it's nicer to put an urban freeway underground, but that alone rarely justifies the cost.

What I DO think we will see more of in the future is urban freeways simply being removed rather than rebuilt when they reach the end of their design life, because it's the cheapest option and also because it better fits the philosophy of trying to place more emphasis on other modes of transportation.

[Bruce]

And speaking of I-5 lids...this got proposed today: http://www.capitolhillseattle.com/2015/09/a-freeway-lid-in-push-for-hill-friendly-convention-center-expansion-thinking-too-small-how-about-a-45-acre-park-along-i-5/

[peterj920]

Realistically, given the issues of the Big Dig and the Alaskan have and are dealing with, I imagine the US is going to avoid urban or long rural freeway tunnels at any cost. Certainly, the Big Dig and the Alaskan could theoretically impact any chance of the 710 gap from being built.

Also, American cities are not typically as space-constrained as cities on other continents are. Tunneling is expensive no matter what runs through it and is usually only the method of choice if building at or above ground level is impractical.

From the perspective of aesthetics it's nicer to put an urban freeway underground, but that alone rarely justifies the cost.

What I DO think we will see more of in the future is urban freeways simply being removed rather than rebuilt when they reach the end of their design life, because it's the cheapest option and also because it better fits the philosophy of trying to place more emphasis on other modes of transportation.

Other modes of transportation can't make up for a freeway.  Lightly traveled freeways in economically depressed areas may be removed (Inner Loop in Rochester, NY), but in the vast majority of bigger cities the freeways are going to be rebuilt.  If a freeway has between 80,000-120,00 VPD, no city street or mass transit can make up for that volume of traffic. 

[Bruce]

Realistically, given the issues of the Big Dig and the Alaskan have and are dealing with, I imagine the US is going to avoid urban or long rural freeway tunnels at any cost. Certainly, the Big Dig and the Alaskan could theoretically impact any chance of the 710 gap from being built.

Also, American cities are not typically as space-constrained as cities on other continents are. Tunneling is expensive no matter what runs through it and is usually only the method of choice if building at or above ground level is impractical.

From the perspective of aesthetics it's nicer to put an urban freeway underground, but that alone rarely justifies the cost.

What I DO think we will see more of in the future is urban freeways simply being removed rather than rebuilt when they reach the end of their design life, because it's the cheapest option and also because it better fits the philosophy of trying to place more emphasis on other modes of transportation.

Other modes of transportation can't make up for a freeway.  Lightly traveled freeways in economically depressed areas may be removed (Inner Loop in Rochester, NY), but in the vast majority of bigger cities the freeways are going to be rebuilt.  If a freeway has between 80,000-120,00 VPD, no city street or mass transit can make up for that volume of traffic. 

I'm pretty sure that putting as many buses on the same freeway would make up for that volume of traffic.

But seriously, for urban areas there needs to be a balanced approach to transportation planning (which will need to be leaning towards transit until it can catch up to the amount of highway construction we've had in the last 60+ years). It's a lot easier to build light rail tunnels than it is to build highway tunnels (see Seattle: University Link's light rail tunnels are finishing under budget and 6 months ahead of schedule next year while Bertha is still not drilling and won't finish for another 3 years).

[peterj920]

Realistically, given the issues of the Big Dig and the Alaskan have and are dealing with, I imagine the US is going to avoid urban or long rural freeway tunnels at any cost. Certainly, the Big Dig and the Alaskan could theoretically impact any chance of the 710 gap from being built.

Also, American cities are not typically as space-constrained as cities on other continents are. Tunneling is expensive no matter what runs through it and is usually only the method of choice if building at or above ground level is impractical.

From the perspective of aesthetics it's nicer to put an urban freeway underground, but that alone rarely justifies the cost.

What I DO think we will see more of in the future is urban freeways simply being removed rather than rebuilt when they reach the end of their design life, because it's the cheapest option and also because it better fits the philosophy of trying to place more emphasis on other modes of transportation.

Other modes of transportation can't make up for a freeway.  Lightly traveled freeways in economically depressed areas may be removed (Inner Loop in Rochester, NY), but in the vast majority of bigger cities the freeways are going to be rebuilt.  If a freeway has between 80,000-120,00 VPD, no city street or mass transit can make up for that volume of traffic. 

I'm pretty sure that putting as many buses on the same freeway would make up for that volume of traffic.

But seriously, for urban areas there needs to be a balanced approach to transportation planning (which will need to be leaning towards transit until it can catch up to the amount of highway construction we've had in the last 60+ years). It's a lot easier to build light rail tunnels than it is to build highway tunnels (see Seattle: University Link's light rail tunnels are finishing under budget and 6 months ahead of schedule next year while Bertha is still not drilling and won't finish for another 3 years).

Light rail has been nothing but a white elephant in most cities.  They are built way over budget, and ridership is never as high as projected.  In dense cities such as Chicago and New York, the train systems carry a high volume and there is a central city that people want to go to.  In most other cities, trains don't work and streetcars are an even bigger waste of money.  I do agree that bus systems are needed, but the majority of people continue to drive because it is way more convenient to go directly from point A to point B.  Despite that, some people still rely on buses and I support them because the only cost is the cost of the buses, there isn't any extra infrastructure other than roads that everyone else uses.  With mass transit, there has to be a walk to a stop, then there may be a transfer or two, then there will be a stop a few blocks away from where someone needs to be.  Fuel taxes pay for road work, so it's a user based system.  Mass transit has to be subsidized by additional taxes because in almost all cases, the fares don't cover operating expenses.  Sure, you can load freeways up with buses, but the reason why there aren't more is because there isn't enough demand.

[Duke87]

Other modes of transportation can't make up for a freeway.  Lightly traveled freeways in economically depressed areas may be removed (Inner Loop in Rochester, NY), but in the vast majority of bigger cities the freeways are going to be rebuilt.  If a freeway has between 80,000-120,00 VPD, no city street or mass transit can make up for that volume of traffic.

Oh I agree (in most cases). But the planning community at large seemingly does not. And given the increasingly broke nature of many states, don't be surprised if they at some point start downgrading freeways simply because it's all they can afford to do. Adding intersections to a freeway sucks but it's better than letting bridge structures fall apart and having nothing when they collapse.

[Rothman]

Other modes of transportation can't make up for a freeway.  Lightly traveled freeways in economically depressed areas may be removed (Inner Loop in Rochester, NY), but in the vast majority of bigger cities the freeways are going to be rebuilt.  If a freeway has between 80,000-120,00 VPD, no city street or mass transit can make up for that volume of traffic.

Oh I agree (in most cases). But the planning community at large seemingly does not. And given the increasingly broke nature of many states, don't be surprised if they at some point start downgrading freeways simply because it's all they can afford to do. Adding intersections to a freeway sucks but it's better than letting bridge structures fall apart and having nothing when they collapse.

I don't see downgrades happening on freeways with decent VPD due to maintenance costs.  The rationalizations are more about how elevated freeways are barriers in the communities they pass through and therefore must be lowered and made into a boulevard...which somehow is better.

Now, with freeways that are underutilized, I would not be surprised to see them get the Robert Moses Parkway treatment.

[peterj920]

Other modes of transportation can't make up for a freeway.  Lightly traveled freeways in economically depressed areas may be removed (Inner Loop in Rochester, NY), but in the vast majority of bigger cities the freeways are going to be rebuilt.  If a freeway has between 80,000-120,00 VPD, no city street or mass transit can make up for that volume of traffic.

Oh I agree (in most cases). But the planning community at large seemingly does not. And given the increasingly broke nature of many states, don't be surprised if they at some point start downgrading freeways simply because it's all they can afford to do. Adding intersections to a freeway sucks but it's better than letting bridge structures fall apart and having nothing when they collapse.

I don't see downgrades happening on freeways with decent VPD due to maintenance costs.  The rationalizations are more about how elevated freeways are barriers in the communities they pass through and therefore must be lowered and made into a boulevard...which somehow is better.

Now, with freeways that are underutilized, I would not be surprised to see them get the Robert Moses Parkway treatment.

I agree, but the downgrades would happen in economically depressed cities.  Rochester, NY and Buffalo, NY are only a fraction of what they once were years ago, which is why downgrades are happening there.  2 other cities where downgrades could happen are Dayton and Youngstown, OH that have really shrunk.  In Milwaukee, WI, Former Mayor Nordquist succeeded in tearing down a stub freeway that was supposed to be longer, promising economic development.  15 years later, most of the land remains vacant.  He had another proposal to tear down I-794, which is an elevated freeway downtown, but was shot down because it carries 105,000 VPD, and there would be nowhere to put that kind of traffic.   In the case of Rochester, NY where the inner loop is being torn down, I think it's an admission that Downtown Rochester is not as prosperous as it once was.  If there was enough traffic that went downtown, the city would be more vibrant and more people would want to go Downtown.  I don't buy the argument that urban freeways separate cities because they bring people into the city, and in a lot of cities people drive and they make it easier to access the inner city.  For example in Milwaukee, the north side has no freeway access and that part of the city is economically depressed.  There was a mall, Northridge, that closed down.  On the south side, I-894 runs across it, and there is a mall, Southridge that was developed by the same group that developed Northridge, and it continues to stay open and attract economic development in the area.  If freeways are so bad in urban areas, why is it that areas with freeway access attract development while areas without freeways attract less development or force businesses to relocate?  And, can someone explain to me why in Milwaukee, the area of the city that does not have freeways is in worse shape than the areas that have easier freeway access?

[Occidental Tourist]

The Alaskan Way Viaduct replacement debacle has show that it's smarter to split up freeway tunnels into two smaller tunnels instead of going all-in. I would've preferred the temporary mess of a demolished viaduct and cut-and-cover construction instead of waiting on Bertha.

I'd love to see I-5 in Downtown Seattle get lowered a bit further (with tunneling some segments where necessary) where possible and fully covered with a terraced park lid.

Any talk of them abandoning the n/b tunnel due to the budget issues and doing a surface routing?

[roadman65]

I would love to see NJ 21 buried under Downtown Newark, however NJ is broke as they are having trouble keeping up with the existing road network that is so under capacity. 

However, maybe using air rights like they did in Dallas, Texas and Phoenix creating parklands over the freeways.  Just built a deck above the freeway, and voila you have your tunnel and the neighborhoods above reunited.

In a case like the Gowanus in NYC, that would need to be tunneled like the great dig, but I would love to see it (even though impossible from a financial standpoint).  Turn 3rd Avenue into a boulevard and reunite the Brooklyn Bayfront with its interior as the highway seems to currently put a wall between the neighborhoods on both sides of I-278.

[iBallasticwolf2]

I'd love to see a cap on I-71 in downtown Cincinnati. Make the cap into a downtown Greenway. I-71 is already depressed so I-71 wouldn't have to be lowered as far as I know. Bridges would have to be redone though.

[froggie]

Light rail has been nothing but a white elephant in most cities.  They are built way over budget, and ridership is never as high as projected.

While it is true that there are some "white elephant" LRT projects here and there (thinking mostly Norfolk here), there are plenty of very successful lines elsewhere, including North Jersey, Minneapolis, Houston, and Seattle.  The Minneapolis LRT lines, in particular, have blown out their ridership projections...meeting ridership levels 15-some years sooner than forecast.

[kkt]

The Alaskan Way Viaduct replacement debacle has show that it's smarter to split up freeway tunnels into two smaller tunnels instead of going all-in. I would've preferred the temporary mess of a demolished viaduct and cut-and-cover construction instead of waiting on Bertha.

I'd love to see I-5 in Downtown Seattle get lowered a bit further (with tunneling some segments where necessary) where possible and fully covered with a terraced park lid.

Any talk of them abandoning the n/b tunnel due to the budget issues and doing a surface routing?

No, at least not publicly.  Digging should resume soon and if there are no further major problems the project as a whole will be only a little over budget.

[jp the roadgeek]

Love to see one built under Long Island Sound.  Also, there's the matter of burying I-84 under the Aetna Viaduct in downtown Hartford.

[roadman]

Besides the greater cost of building tunnels or 'cut and cover' decks through urban areas, IMO, the asethetic advantages of burying freeways are more than offset by the additional costs and other resources required to operate and maintain them on a daily basis.  There's also one important consideration that is rarely looked at beforehand - the movement of hazardous materials through the area once the feeway is put underground.

[vdeane]

I don't buy the argument that urban freeways separate cities because they bring people into the city, and in a lot of cities people drive and they make it easier to access the inner city.

But that is exactly the problem.  The cities don't want people to be "brought in" to "access" the inner city.  They want people to live there in a walking-first lifestyle.  And pedestrians tend not to like to walk over or under things, regardless of whether it's actually easier to cross than a boulevard or not.  The perception is there.  Plus boulevards can have development immediately adjacent to them and midblock crosswalks.

As for only wanting to downgrade freeways that are sparsely used... tell that to the people who want to remove I-787 (AADT ~85k) and I-81 (AADT ~92k).  Each freeway removal leads to more ambitious pushes to remove more.

[Rothman]

As for only wanting to downgrade freeways that are sparsely used... tell that to the people who want to remove I-787 (AADT ~85k) and I-81 (AADT ~92k).  Each freeway removal leads to more ambitious pushes to remove more.

Out of the two of those, I'd lay my bet on I-81 as more likely to become a boulevard.

Of course, both Albany and Syracuse have factions that want tunnels.

[peterj920]

I don't buy the argument that urban freeways separate cities because they bring people into the city, and in a lot of cities people drive and they make it easier to access the inner city.

But that is exactly the problem.  The cities don't want people to be "brought in" to "access" the inner city.  They want people to live there in a walking-first lifestyle.  And pedestrians tend not to like to walk over or under things, regardless of whether it's actually easier to cross than a boulevard or not.  The perception is there.  Plus boulevards can have development immediately adjacent to them and midblock crosswalks.

As for only wanting to downgrade freeways that are sparsely used... tell that to the people who want to remove I-787 (AADT ~85k) and I-81 (AADT ~92k).  Each freeway removal leads to more ambitious pushes to remove more.

I live in the Green Bay area and there is no freeway access to Downtown Green Bay.  It should be set up perfectly like some urban planners want.  Surface streets with pedestrian access.  If it's so great, why is Downtown Green Bay struggling while the areas along the freeways are thriving and attracting development? 

[The Ghostbuster]

Interesting replies. I personally would favor tunnels replacing existing freeways that are considered barriers or eyesores to existing neighborhoods. Or to complete missing links in the freeway system like Interstate 710. Of course, there is always the matter of how much tunnels will cost, and those costs are quite steep. On the other hand, if it helps keep neighborhoods united, or reunites them, I think they may be worth it.

[PHLBOS]

One item that gets overlooked regarding tunnel-type freeway systems that adds to the overall cost is the more intesified infrastructure associated w/such particularly ventilation.  An elevated viaduct or even an at-grade freeway does not require a tunnel-like ventilation system.

Another item that gets overlooked is that the flexibility of adding, modifying or deleting a ramp over time (due to change in conditions or development) is completely out of the question; not without creating a more massive disruption to accomplish such.

Case and point: prior to the Big Dig circa the mid-to-late-1980s, a developer wanted to erect a high-rise (International Place) basically in the path of the original, curvy High St./Congress St. exit ramp (then Exit 23) off the Central Artery (I-93).  As a result, a brand new straighter off-ramp replaced the original ramp (IIRC, the developer footed the cost); such was situated between I-93 and the new skyscraper.

Another example: In Philly near Penns Landing, circa 1991; PennDOT replaced a short off-ramp from I-95 north (that used to drop one off at Water & Morris Sts.) with a wider more elaborate ramp that connected to Columbus Blvd. (Exit 20).

Good luck trying to do either of the above with a tunnel system.

There's also one important consideration that is rarely looked at beforehand - the movement of hazardous materials through the area once the feeway is put underground.

Another issue that could discourage (not necessarily prohibit) more freeway tunnels being built is that such likely has more security-related issues and are greater targets for terrorists (sarin/nerve gas attack similar to what happened in a Japanese subway over 20 years ago).  During the 2004 DNC Convention held in Boston; the newly-opened I-93/O'Neill Tunnel (that replaced the Artery) was closed to all traffic due to security reasons.  IMHO, had the Artery still been present; it would've only had a smaller segment of it closed or it wouldn't have been closed at all.

I'm sure any new tunnel being proposed has to go through additional DHS scrutiny prior to approval.

As far as those advocating teardowns/downgrades, etc.; one needs to keep in mind that those highways don't just only serve commuters but such also serve as commerce conduits for all types of delivery vehicles.  If those highways weren't there; it would take a lot longer for goods and services to get delivered to businesses and residences located in the city.  Such would likely show up in the form of more expensive delivery charges.

I live in the Green Bay area and there is no freeway access to Downtown Green Bay.  It should be set up perfectly like some urban planners want.  Surface streets with pedestrian access.  If it's so great, why is Downtown Green Bay struggling while the areas along the freeways are thriving and attracting development?

My older brother recently read about the history of Boston's Central Artery; how it came to be and what the areas were like prior to its existence.  Long story short; had the Artery never been built, areas like the Financial District as it is today would have probably never come to fruition... at least not in Downtown Boston.