Forum Topic

Hammersmith flyover tunnel!

Interesting to see it being discussed in the Local Plan, how about getting a bridge sorted first? Its like learning English without A,B,C’s!

John Bird ● 23d65 Comments

Of course, you miss the obvious fact that a large proportion of vehicles using the flyover are commercial ones. Or is the plan to stop those from using London’s taxpayer funded roads as well? Good luck getting your home deliveries in that case.Unlikely that anything will happen in your lifetimes, chaps.

Simon Hayes ● 4h

Here are Steve Cowan in his own words:"It would be a land reclamation issue, recycling the profits made from the land into putting in a tunnel," Cllr Cowan told members. "That would need a different approach to transport in this city and it's something we're planning for and hoping for, but clearly it would an issue we would have to work with the Mayor on and Central Government on. But it is something that would stack up because it would be self-financing ultimately."You seem to be arguing against yourself, first saying that policies which might discourage vehicle use are ineffective, but then admitting that other factors such as ULEZ, might do just that! Further, more home deliveries are leading to less people using their cars, or not getting one in the first place. The fact remains that as London's population has grown, and home deliveries have increased, traffic has fallen. There is no reason to think this trend will not continue.I haven't said anything about traffic across the flyover being non discretionary. However, given that the number of vehicles crossing it have fallen by 26% since 2000, it's difficult to argue vehicle numbers on it are a fixed quantity that will take some "magic" to reduce. On current trends, traffic will have at least halved by the time the flyover reaches the end of its current life.

Tom Pike ● 7h

Even in the US, the home of car centred city design, there are lots of examples of freeway removal projects plus cities in other countries as well.Of course this is beyond the comprehension of the carbrained.Bonaventure Expressway Montreal, Canada 2016 Elevated highway demolished and replaced with an urban boulevard and parklandCatharijnebaan Utrecht, Netherlands 2010 Highway demolished and replaced with canal and green spaceCentral Freeway and Embarcadero Freeway San Francisco, United States 1993 Replaced by at-grade boulevards following 1989 Loma Prieta earthquakeCheonggye Elevated Highway Seoul, South Korea 2003 Replaced with artificial stream and green spaceCogswell Interchange (Harbour Drive) Halifax, Canada 2021 Freeway-to-boulevard conversionGardiner Expressway Toronto, Canada 2001 Partial demolition; exit ramps replaced with parklandHarbor DrivePortland, United States 1974 Demolished and replaced with Tom McCall Waterfront ParkInnerbelt Akron, United States 2017 Highway closed and redeveloped into parkland and urban developmentInner Loop Rochester, United States 2014 Replaced with surface streets and urban developmentNY 895 (Sheridan Expressway)New York City, United States 2017 Freeway-to-boulevard conversionOak Street Connector New Haven, United States 2013 Highway demolished and replaced with surface streets and urban developmentOklahoma City Crosstown Expressway Oklahoma City, United States 2002 Partial highway-to-boulevard conversionPark East Freeway Milwaukee, United States 2002 Demolished and repurposed into urban developmentNiagara Scenic Parkway Niagara Falls, United States 2019 Highway removed and replaced with surface streets and waterfront parklandSoutheast Freeway Washington, D.C., United States 2016 Partial freeway-to-boulevard conversionVoie Georges-Pompidou Paris, France 2016 Highway removed and replaced with public beaches and urban developmentWest Sacramento Freeway Sacramento, United States 2014 Highway removed and replaced with surface streets and urban developmentWest Side Elevated Highway New York City, United States 1977 Elevated highway demolished and replaced with urban boulevardZhongxiao Elevated Highway Taipei, Taiwan 2016 Elevated highway repurposed from roadway into elevated park. Section next to the North Gate demolished to give an unimpeded view of the gate.Riverfront Parkway (Chattanooga) Chattanooga, United States 2004 Freeway-to-boulevard conversionCypress Street Viaduct Oakland, United States 2005 Freeway-to-boulevard conversionPerimetral Highway Rio De Janeiro, Brazil 2015 Freeway transformed into public space

Michael Robinson ● 18h

As ever, I enjoy the irony in Michael's post. He seems blissfully unaware which makes it even more enjoyable. Whence people opposed the cycleway (dare I say asked for a re-design of something better) he was one saying offer up an alternative which he then summarily shot down as coming from unprofessionals guided by anecdotal evidence. Professionals gave us a mish mash that floods in a drizzle, but I digress.Vision isn't Michael's strong suit. This we know. Myopia is. Odd that tunnel vision can't see the light at the end of this one...

David Lesniak ● 19h

An interesting read about the 100th anniversary of the Great West Roadhttps://diamondgeezer.blogspot.com/2025/05/great-west-road-100.html?m=1

Andrew Jones ● 1d

"The historical route through the area was Chiswick High Rd leading on to King St, Hammersmith Rd.  The A4 as a route through Hammersmith was only built in the 1950s" ...........when there around four million vehicles in GB as opposed to forty odd today.Fortunately planners had the foresight to construct the Great West Road then. Now we need planners with the same foresight to cope with the future.

Adrian Irving ● 1d

'There are many examples of freeway removal projects all over the world'Lots more cities ensuring traffic flows. UK being bankrupted by Miliband's lot and these extreme Just Stop Oil green views he panders to.

Davy Jones ● 1d

"Observational evidence" isn't evidence Francis.  It is just an unreliable anecdote.Many people drive because it is habitual behaviour.  Habits can change.People opposing a tunnel don't need to propose an alternative option.  The people proposing the tunnel need to explain why it is better than alternatives.The historical route through the area was Chiswick High Rd leading on to King St, Hammersmith Rd.  The A4 as a route through Hammersmith was only built in the 1950s.There are many examples of freeway removal projects all over the world, for example, central Seoul. Redeveloping an area does not require existing traffic capacity to be maintained.

Michael Robinson ● 1d

Francis is spot on. A regenerative project such as this pays dividends for generations in ways often overlooked.

David Lesniak ● 1d

Has Cllr Cowan actually ever explicitly stated that the full cost of the tunnel would be covered by realised land value? All the previous statement that I could find from him and his council seem to suggest that it would only part fund it and central government and TfL cash would be needed. Obviously a project which is likely to cost £2billion is not going to be covered by land sales but if you take the increase in qualatitive value of the surrounding area plus the NPV of annual maintenance cost for the flyover you could argue that it is self funding in the broader sense.On the early question of evidence for a the majority of traffic over the flyover being non-discretionary, I know you don't like observational evidence but you will just have to take it from those of us who sometimes drive over it, that the largest proportion of the traffic is taken up by vans, lorries, visibly commercial use cars and Ubers. Even if you make the very dubious assumption that every private car is not being driven for private use, you will still struggle to make a case that the majority of people driving over the flyover are there by choice.On the relationship between population and vehicle growth, I was referring to the fallacy that suppressing private vehicle ownership means that you can avoid a growth in vehicle movements as population density increases, all other things remaining equal. Other factors may come into play, for instance ULEZ, to mean they are not directly linked and longer term London's population growth has not been matched by  vehicle movement growth. However, looking ahead, the increasing dependence of Londoners on next day delivery looks set to push the level of traffic ever higher. When asked to explain the increased level of traffic delays across Chiswick in 2024, Hounslow Council issued a statement blaming it not on the cycleway but population growth. Were they wrong?Those opposing both the flyunder and a new flyover have to explain what exactly they are proposing as a third option. Even if you were to some how magically halve the amount of traffic on a route that has been busy since Roman times, it is impossible to envisage how a ground based road network would comfortably handle volumes and not cause significant displacement. It seems to me that there is an element of shooting down proposals that are both challenging and ambitious while advocating for an alternative that is just pure fantasy.

Francis Rowe ● 1d

Dominik, which of the cities you mentioned have closed bridges to vehicles due to poor maintenance?As you know, this has a significant impact on efficiencies key to a functioning, thriving economy. I must admit the inclusion of Baltimore makes me laugh.

David Lesniak ● 14d

Steve Cowan, leader of LBH, has effectively confirmed the project is a fantasy by suggesting that the land freed up could cover the construction - the value of any extra building land is significantly less than any realistic tunneling costs. Similarly, the money raised by tolling Hammersmith Bridge would never be sufficient to pay for the  financing of the proposed strengthening projects. For both proposals, the costs far exceed the benefits, as demonstrated that it is left to Cowan to suggest these options rather than any company pursuing these as realistic financial opportunities.

Tom Pike ● 14d

New YorkSydneyAucklandMelbourneParisCopenhagenAmsterdamBaltimoreWhat these modern cities have in common is their restrictions on car use, either for reasons of pollution or infrastructure, or both.  They all share widely documented ambitions for reducing reliance on motor vehicles.I think there are conflicting ideas of a ‘modern city’ on this forum, with some based on personal preference rather than facts.

Dominik Klimowski ● 16d

>I wonder if they could have a branch tunnel leading off the flyover replacement one, going under the river ?We could knock down all the independent shops Church Road for the portal... or bring it up under the wetlands centre?

Paul James ● 17d

I wonder if they could have a branch tunnel leading off the flyover replacement one, going under the river ?

Richard Greenhough ● 17d

It depends on its use, Janice. Have you been across it recently? It has had extensive repairs (as we all know), and is  vastly improved. Any deterioration and ongoing repair will be determined by how it continues to be used, but at least the middle is open again.

Dominik Klimowski ● 18d

Spot on.And  New YorkSydneyAucklandMelbourneand many more

Steve Taylor ● 18d

>The bridge is not fit for purpose for a modern city.A modern city like?Paris?Copenhagen?Amsterdam?Baltimore?

Paul James ● 18d

The bridge is not fit for purpose for a modern city. The government certainly has the chicken feed money to repair the bridge. It just needs the political will. The current mayor is doing nothing to help. He loves the traffic chaos in west London. No mayor of any first world country would allow a major arterial bridge to be closed to motorised traffic for so long. It’s ridiculous and quite shameful.

Steve Taylor ● 18d

Seems old Dominik has some problems recognising how the real modern world operates. One wonders if he’s safe to be out on the roads.Not noticed all the Lorrie’s, buses, trucks, taxis as well as cars, Dom? Probably not, as your view seems to be obstructed by the position of your head somewhere around your rear end.The bridge is clearly not in perfect working order. As Janice said it will continue to deteriorate until it becomes a pointless exercise. Do you continually repair something that’s obsolete and expensive or replace it? A phone perhaps? A laptop? Any motor vehicle? Even a bike. No different with this bridge. Indeed, this thread started on the topic of Hammersmith flyover needing to be replaced at some point. Do keep up.

Simon Hayes ● 18d

It will continue to deteriorate and be an ongoing cost for repairs.

Janice Evans ● 18d

We buy our family groceries without driving to the shops. We either carry them, wheel them in a trolley, or take them on a bike. You’ll be surprised how much you can fit into bike panniers. I got 48 bottles of beer and a bottle of sherry in one, for a party a few years ago.My currently carless parents buy groceries, as did my carless grandparents. To my memory none of us were undernourished.I realise these examples are anecdotal, but there are thousands of people out there who do the same. You'd be surprised, Janice.:)

Dominik Klimowski ● 18d

No-one wants to pay to replace an entire bridge which is in full working order. It’s perfectly suitable for modern use, it's just that some people’s definition of modern use is already outdated.

Dominik Klimowski ● 18d

The Victorians would be laughing at us, but not for the reasons you think.

Dominik Klimowski ● 18d

The government could always find the money for infrastructure projects. TfL could also find the cash currently being wasted on nonsense active travel initiatives.As others have argued elsewhere building infrastructure creates economic benefits. Hammersmith Brudge is no different.

Simon Hayes ● 19d

"Of course it can be replaced, with an identical looking one if necessary, but one that is fit for modern use."Of course it could, but it goes without saying it would need to be paid for. And no one appears to be willing to stump up the money needed.

Andrew Jones ● 19d

Quite right Keith.It’s ironic that handsome old buildings are bulldozed when deemed beyond modern use, to be replaced by glass and metal monstrosities. Yet, a piece of important infrastructure only has aesthetic value now so the likes of Dominik can get misty eyed over it. Of course it can be replaced, with an identical looking one if necessary, but one that is fit for modern use.

Simon Hayes ● 19d

The Victorians would laugh at our ineptitude and dithering.

Keith Iddon ● 19d

The bridge has been 'sorted', only it will never be strong enough for the weight of traffic it had in later years.The only option is to replace it with another bridge, which no-one really wants or can afford. People have got used to it now, and Castelnau road, and the streets north of it are so much more pleasant now, as is the bridge itself. I'm there almost every other weekend and it's a positive transformation to the local area.I used to row under that bridge in the 80s and nowadays I still enjoy the views while crossing it. It's a beautiful landmark, in my opinion, and it features in the last James Bond film, for the trivia fans among you.

Dominik Klimowski ● 19d

Morrisons don't carry as much stock, and baking less, will say their fresh salad (not the mixed bags) and veg has good fridge life and never have to throw away food.

Janice Evans ● 19d

Paul balances everything on his head, one item on top of the other. He’s a very clever cyclist.A lot of people still prefer to shop in person, particularly for groceries. A car park is a definite benefit and also encourages passing trade. A case in point is the way the footfall in Brentford Morrisons has dropped off a cliff since it moved to its current location, with a subterranean car park that hardly anyone knows is there. Meanwhile the Lidl on the Morrisons former site is flourishing.There are a lot of people who park in Sainsbury’s in Chiswick to pop down to the High Road too. Convenience for those who are time pressed. Paul is lucky to have a ‘job’ that seems to entail doing very little most days.

Simon Hayes ● 19d

How do you carry groceries on a bike ?

Janice Evans ● 19d

"It's an oversimplficiation for sure, but one van on a circuit delivering 50 shopping orders is less vehicles on the road than 50 people driving to the supermarket and back in massive SUVs..."Just your own simple maths, Paul.I see your also advocating for the reduction of super markets. Why not just kill the High Street off altogether while you're at it? It's clear to me you don't do the weekly shop. Or if you do, you do it for you? Maybe one other? But one can't shop for a family via bike. Not to mention this inane assumption that people only use a car for one thing at a time. That weekly shop often comes after dropping off the kids here, there and everywhere, getting the car serviced, picking up prescriptions, dropping off an elderly parent at the doctor, etc. Not that this is advanced calculus, but perhaps beyond your comprehension.

David Lesniak ● 19d

>He's assumed there are two options for groceries. Delivery and collection by car.Eh, as somebody that gets groceries deleivered sometimes, walks to the shop to get them, cycles to the shop to get them and sometimes (very rarely!) drives to the shop to get them I'm not sure how you came to that conclusion?I would mostly cycle to get them, one less car parking space used up, fewer motor vehicles on the road, benefits all.

Paul James ● 19d

Agreed, Simon. I'm new to Paultown but there are some interesting tidbits populating his brain.He's assumed there are two options for groceries. Delivery and collection by car.Of course people could walk but the advent and evolution of home delivery has changed footfall on the high streets. Not only for groceries but for all manner of retail. Banking anyone? Why bother if you can do it online. On the tube on your way home...Not for everyone but as the population ages this trend will only continue.

David Lesniak ● 19d

“the link has not been broken between population growth and the number of vehicle movements.”That’s just not true. First of all, the number of car trips per person has dropped dramatically in London, nearly halving over the last 20 years. Further, London has grown dramatically without expanding overall vehicle mileage over the same period. Last year 19.2 billion miles were driven with a population of nearly 10 million. Twenty years ago 20.4 billion miles were driven with a population of 7.4 million. So while the population has grown by a 34%, vehicle mileage has dropped by 6%. The link you claim simply does not exist. https://content.tfl.gov.uk/travel-in-london-2024-car-ownership-trends-acc.pdfhttps://roadtraffic.dft.gov.uk/regions/6

Tom Pike ● 19d

its best to go to the supermarket or you miss all the reductions,

Janice Evans ● 20d

Paul clearly doesn’t understand how the supermarket delivery system works. Not a surprise. People book a delivery slot, so your neighbours might get a delivery at 8am, but your comes at 3. Different van, different driver.Then add in the various supermarket delivery vehicles and you get a multitude of then on the road.Of course, two of the most popular supermarkets - Aldi and Lidl - don’t deliver at all and tend to have nice big car parks for customers.This is all the usual guff Paul has been spouting in Ealing Tiday for years. It convinced nobody there so he’s switched to this forum in the vain hope that he might persuade some here.As for all the traffic on the Hammersmith flyover? It clearly doesn’t occur to some that these might not be local journeys but part of much longer ones, often from outside London. Just because they might be cars doesn’t necessarily mean they are leisure journeys either. Quite a lot of businesses operate without vans or Lorrie’s and use cars instead.What next, barriers on the M4 prohibiting non-Londoners from entering? Didn’t Khan float the idea of a toll to enter the capital that was shot down as soon as it was mentioned?

Simon Hayes ● 20d

>Think Covid made people lazy with more deliveriesIt's not not lazy for everybody to drive to a supermarket every week, instead getting their stuff delivered instead, it makes sense on many levels. Less traffic on the roads, less pollution, less congestion, and no need for MASSIVE car parks or huge supermarkets for people to wander around to start with.

Paul James ● 20d

Think Covid made people lazy with more deliveries, find I'm buying most things online, however do like to do the weekly food shop myself.

Janice Evans ● 20d

>Buying one's groceries while on the tube home to have them delivered when you arrive home yourself will never result in less vehicles on the road. It simply won't.It's an oversimplficiation for sure, but one van on a circuit delivering 50 shopping orders is less vehicles on the road than 50 people driving to the supermarket and back in massive SUVs...

Paul James ● 20d

On my way to Wembley this AM and passed loads and loads of Amazon vans all of which were petrol. Where is Paul's righteous indignation for that?I've yet to hear him come up with an alternative to all the deliveries generated, increasingly so, with online shopping multiplying. Francis is, again, spot on. Buying one's groceries while on the tube home to have them delivered when you arrive home yourself will never result in less vehicles on the road. It simply won't.

David Lesniak ● 20d

"the overwhelming proportion are non-discretionary such as deliveries."Evidence, please.Francis, you have a track record of making things up to fit your prejudices and this looks like another example unless you have some proof.A quick bit of actual research shows that about 80% of vehicles on the A4 are cars, not vans and goods vehicles.

Michael Robinson ● 20d

>the link has not been broken between population growth and the number of vehicle movements.It clearly needs to be broken, but you're right, will probably never be whilst many people demand solutions as to what to do with all the motor vehicle movements, rather than coming together to work out ways of reducing them overall, and there are plently of ways of doing that, but so many are fought against tooth and nail.

Paul James ● 20d

Paul, despite falling car ownership, a collapse in younger people learning to drive, measures such as ULEZ, increase charges for parking, car free estates and a whole host of other measures, the link has not been broken between population growth and the number of vehicle movements. This is because, as Janice alludes to, the overwhelming proportion are non-discretionary such as deliveries.The population of LBHF is projected to grow by about 6-7% over the next decade and much of this growth is expected to be concentrated along the A4 corridor. Even if not one single person among the new arrivals owns a car, they will collectively generate thousands of extra vehicle movements every day.Even a relatively progressive and pro-active council like LBHF recognises this challenge and knows that there is simply no other choice than to plan for the replacement of Hammersith Flyover either on a like for like basis or with a tunnel.

Francis Rowe ● 20d

>Short journeys are usually for the supermarket shopping which would be local.Most short journeys in cars are for supermarket trips?

Paul James ● 20d

No I said short journeys are usually to the supermarket which would be local.

Janice Evans ● 20d

>Someone has to drive the car they could be cabs or doing deliveriesDo you think that's all of them though?

Paul James ● 20d

Short journeys are usually for the supermarket shopping which would be local.

Janice Evans ● 20d

Someone has to drive the car they could be cabs or doing deliveries, I get things delivered by car from eBay.

Janice Evans ● 20d

I've walked and cycled across hammersmith bridge, you can see though the gaps in the deck and it wobbles and shakes, it clearly was never intended to be a bridge that transported the amount or type of motor traffic that ended up going across it.

Paul James ● 20d

>the road network must be at its optimum.Any road network is never going to be optimum if it's stuffed full of cars with just a driver in that could have used another mode of transport, considering many many journeys in cars are actually very short.Add more roads in an attempt to counter this and you get ... evenm more driving.Key example in the article about this on the front page"The flyover, which was opened in 1961, was intended to reduce the levels of traffic in Hammersmith."WHOOOPS!!!https://www.chiswickw4.com/default.asp?section=community&link=https://neighbournet.com/server/common/hfroad014.htm

Paul James ● 20d

Agreed, Francis.What Michael always ignores is how increased development will deliver increased demand on roads. He can carp on about reducing private car use all he wants but the fact remains more Ubers, cabs and deliveries will be required to service all these new residents and businesses. And for those to be cost effective and energy efficient the road network must be at its optimum.

David Lesniak ● 20d

And the bridge?

John Bird ● 21d

All these big roads are anachronisms from years ago when they thought they could install a motorway network in London and everybody was going to drive all the time.Adding more silly disasterous expensive stuff to fix old mistakes was never going to be a good idea.

Paul James ● 21d

Bet it's safe to assume it won't happen. They can't even manage to repair or rebuild the bridge. Can't work out why even the idea sets some teeth gnashing

Davy Jones ● 21d

Your memory appears to be worse than a goldfish Francis.You need to check my forum posts to see I expressed no support or opposition for the Hogarth scheme.  I was just commenting on some of the nonsense posted by some of the forum brains trust.Aa usual, you just make things up to fit your prejudices and this is yet another example.It is good that you are supportive.  Given your track record, that means it is safe to assume it will never happen.

Michael Robinson ● 21d

Those of us with memories longer than goldfish will recall that you were one of the most passionate defenders of TfL's plans for widening the A4 by Hogarth Roundabout earlier this year. The reality is LBHF are constrained by the world as it is rather than you might like it to be and population density in the area around the Hammersmith Flyover is predicted to rise over the next few decades and therefore the council has to plan for increased levels of traffic.You are probably not wrong that the flyunder plan is 'bonkers', faces significant technical challengers, does not have buy in from neighbouring authorities and would lead to years of disruption as well as costing a huge amount of money. However, many of these objections could be made against the rebuilding option, and, if LBHF is right about the land value premium, the tunnel may be less burdensome on the tax payer.You are also correct that the technical basis for this scheme remains very sketchy. However, we can all agree that while it is extremely challenging, it is not impossible. The  key question is whether LBHF are proposing this in the knowledge that it will never happen so they can claim TfL and neighbouring boroughs stymied their visionary plan or if they genuinely intend to press forward and overcome the inevitable obstacles to the scheme. I really hope it is the latter.

Francis Rowe ● 21d

Oh yes, the concept is definitely “visionary”.Trouble is, it is like the vision of a failed 1960s urban planner who wants to direct a hosepipe of cars into the centre of London and the idea the volume of cars should be reduced in the first place is beyond their comprehension.

Michael Robinson ● 21d

Perhaps when Michael wakes up he'll enjoy the irony he has provided for our enjoyment.He sees a visionary idea to reduce the impact of cars as "stupid" and thinks NIMBYism is at play. That last bit is shocking given his support of all things that ignored any input from a broader swath of the populace than, say, his buddies in Grove Park or the Hounslow Cycling Campaign.

David Lesniak ● 21d

I didn't say it wasn't possible, just that it was stupid and that report is a good illustration why.The report wasn't "extensive".  If you had read it, you would see that it refers to itself as a "short study".Most things are possible if you throw enough money at it, and it would be a lot of money.In the report, 39% of the LBHF residents surveyed wanted the tunnel entrance in Hounslow, a 100m+ trench right by Chiswick House.  The ultimate in NIMBYism. Of course, they didn't ask residents in Hounslow.  Of course the Hammersmith flyover won't last forever but that doesn't mean it needs to be replaced by a tunnel. They could remove the flyover, "unwind" the gyratory so it only goes around part of the Broadway, freeing up space on the other sides.  If they halved the lanes on the A4, that would also free up lots of space for development and making the area more attractive.

Michael Robinson ● 22d

LBHF commissioned an extensive feasibility study- & unlike local armchair experts they didn't find it bonkers, concluding:'No matter how many expensive repairs areconducted, the flyover won’t last forever. Overthe next 20 years London will continue to growwith more jobs being created and houses built.Whether or not this results in significant increasesin traffic on our road network is unclear. Whatis clear is that a plan for the future of the A4corridor is required and that tunnelling underHammersmith is possible. The council has takenthe initiative in producing this feasibility report andnow is the time for others to take this investigationforward. There are some significant environmentaland economic challenges to overcome. However,as we have seen, the resulting reimagination ofHammersmith town centre could be momentous.'https://www.lbhf.gov.uk/sites/default/files/section_attachments/flyunder_feasibility_study_web_medium_tcm21-187089.pdf

Davy Jones ● 22d

It was always a bonkers proposal anyway. Both ends of a tunnel need a "portal" which is basically a trench with length determined by clearance needed for the tunnel below the underground, headroom for the type of vehicles permitted in the tunnel and an acceptable gradient to get down and up again.The portals at both ends would likely be 100+m in length and of course would create severance at their locations, there would need to be bridges built for pedestrians/cyclists to get over them and no clue how they deal with the storm drains going to the river.LBHF of course didn't want the portals to sully their borough and said they should be in Hounslow and K&C.Additionally, a significant proportion of the traffic on the A4 isn't going east-west but is also going north and south so in addition to the tunnel, there would also need to be a surface road network.Its a classic example of trying to sweep a problem under the rug but just moving a problem from one place to another.

Michael Robinson ● 22d

And yet you can all build a lovely sewer.

David Lesniak ● 22d

(and the A4 elevated section, and A40 westway)

Paul James ● 22d

...ssshh hammersmith bridge can't be fixed to carry the amount of traffic it ended up carrying...Same for the Hammersmith Flyover.And soon the be the same for Chiswick Bridge...

Paul James ● 22d

It has taken longer than the entire duration of W W 2 to fix Hammersmith Bridge so based on that timescale this much larger project may be finished sometime in the middle to end of this century.Hopefully.

Adrian Irving ● 22d

Maybe they could just move the unwanted Hammersmith flyover and use it to cross the river!

Peter Evans ● 23d