The Deterioration of Flyover structures in London

[MotorwayGuy]

Isn't the whole point of the PFI deal that it pays for the replacement flyover, so the at a minimum we should get a replacement flyover built by the PFI company?

Another problem flyover is the A41 one at Brent Cross, which now has a weight restriction.

The PFI Scheme rebuilt every junction from the A12 up to and including Movers Lane, it does seem odd that the roughly 1.5 mile section between Movers Lane and the offline Dagenham bypass which apparently is also part of the PFI was basically ignored. There are quite a few frontage accesses as well as the Renwick Road and Gale Street which make this section challenging (I'm not sure if similar issues existed on the rest though). The right turn into Renwick Road was removed a few years ago but for some reason the traffic lights were retained. Why remove this movement when the conflicting Westbound traffic has to stop at a red light anyway?

It at least removed the traffic lights for eastbound traffic. And a potentially dangerous movement for traffic joining the A12 at the Lodge Avenue flyover wanting to turn right into Renwick Road, and having to cross into the 3rd lane.

Through traffic Eastbound didn't have traffic lights, only traffic turning right into Renwick Road did (there was also only one signal head with no primary, which I thought wasn't permitted).

[WHBM]

There's been discussion on one of the other threads regarding the PFI contract for the A13, back when the other flyovers nearby were upgraded.

Isn't the whole point of the PFI deal that it pays for the replacement flyover, so the at a minimum we should get a replacement flyover built by the PFI company?

I think the prior A13 PFI discussion referred to included me, when I posted the complete PFI document.

It is correct that the PFI payments since 2000 included all the works at the "start" of the contract and payments, and also for the Movers/Renwick section to be equally improved and grade separated at the end, which is 30 years after the start, as part of the fixed annual payments. There have been lots of changes to the PFI since it started, the original joint owners have sold out their shares to others and the scope has been changed. In particular the Limehouse Link, originally a separate PFI, is now merged in, and the offices and control room are in the former Limehouse Link HQ, located over the Limehouse east branch exit portal, and trading as Road Management Services (A13) plc.

Word on the street is TfL are looking to save money by relieving the PFI of their liability to rebuild the Movers section, in return for not paying the full PFI amount (or anything) for the remaining duration. This is complicated by a concern that the fund which has supposedly been built up over 30 years to pay for this may have been paid out as dividends; it is supposedly guaranteed by parent company guarantees, but these guarantors are no longer the parent companies. Also, TfL is dependent on funds from the government, who may well say if the PFI payments are reduced, the government will reduce their payments to TfL commensurately. It's all high level negotiation. The policy of TfL has of course changed over the 30 years of the PFI - the original substantial A13 rebuilding, like the separate Limehouse Link, was part of the Docklands Redevelopment, now also lost in time.

At the very least the Movers flyover should be repainted - it still has its paint from its 2000 refurbishment a quarter-century ago, with extensive rusting showing on the steelwork.

The Renwick Road junction, although converted to a LILO, would still have an unacceptable junction if not signal controlled. It has a high HGV content, a sharp turn for such vehicles into the westbound A13 mainline, and no acceleration lane. The pub on the corner, the 'Ship & Shovel' was derelict for some years but has been sold and reopened as an evening "gentleman's club", although the gentlemen patrons are apparently mainly itinerant European HGV drivers ... however it is immediately followed by industrial frontages and further vehicles turning in and out, who doubtless take advantage whenever the signals are on red. We could all come up with a scheme for this, but TfL doesn't do such any more. It is also of course under the control of the PFI, who now it has fallen into the hands of financial speculators would charge an arm and six legs for it.

Regarding frontages, there are worse on the rebuilt A13 sections elsewhere - look at these houses fronting directly onto the main 50mph carriageway at Canning Town :

https://www.google.com/maps/@51.5173854 ... ?entry=ttu

[Ben302]

Then we have things like the A13 Lodge Avenue Flyover. Replacing this means all traffic will be forced through the roundabout while it is replaced as there is no room to build it offline. It's cousin at Movers Lane was replaced in the 90s, which would have had similar issues, does anyone know how traffic was dealt with then?

I remember when the old Movers Lane flyover was replaced. Much of the A13 between there and Limehouse was like a building site owing to the DBFO rebuild, with narrow lanes and traffic switching from one side to the other on temporary alignments. The A13 mainline was shunted onto 3 narrow lanes along the former slip roads and the flyover was fenced off and then demolished, with traffic using a temporary mini roundabout to access Movers Lane. Ass construction of the junction progressed the roundabout was replaced with a signalised crossroads while the underpass was created. I remember there being massive queues when the mainline was running on the future slip roads as three lanes of traffic had to stop to allow traffic to exit Movers Lane. When the underpass opened (it was one of the last on the A13 project to do so), the effect was immediate with queues almost vanishing.

[Peter Freeman]

At some of the mentioned locations, perhaps replacement isn't necessary - improvements at ground level might be sufficient. This could apply at several places, though probably not at Chiswick, and definitely not at M5/M6, etc. Let's take Gallows Corner and Hogarth as the best examples.

At the flyovers' times of construction, the at-grade intersections were obviously deemed so incapable that the only solution was a flyover. And it was a 1960's trendy thing to do. What were these incapable intersections? Roundabouts of course - and they still are. We know now that a properly designed signalised intersection can handle far more traffic than the discredited roundabout. We should therefore provide a proper high-capacity signalised intersection, and save ourselves the cost of a new flyover.

It is relevant that, in both cases, those roads' continuations are not fully grade-separated. So why should these locations be? I'm not saying that roads with, generally, flat intersections should never have isolated flyovers. Yes, they may, but only when a flat intersection, matching the road's style, really won't suffice.

In summary, a flat intersection should have been the solution then, and should be the solution now if flyover decommissioning becomes necessary.

[Chris5156]

At the flyovers' times of construction, the at-grade intersections were obviously deemed so incapable that the only solution was a flyover. And it was a 1960's trendy thing to do. What were these incapable intersections? Roundabouts of course - and they still are.

It shouldn't be overlooked that both flyovers were intended to be temporary, with a much bigger rebuild to follow as a permanent fix. As a result it wasn't thought economical to completely rebuild the junction. Hence a temporary flyover to augment the roundabout was preferred to replacing it. (When I say "temporary", I really do mean it: it was thought at the time that, once they were no longer required, they could be dismantled and installed at some other problem junction to serve as a stopgap all over again.)

Now, of course, those junctions will never get a "permanent" scheme for large-scale grade separation, so a high capacity signalised junction would make sense. But in the 60s, the logic was pretty sound.

[Runwell]

In terms of the A13 and the Lodge Avenue flyover, one problem with resorting to a surface level solution is that a lot of issues at the junction are caused by the traffic signals on Lodge Avenue, at the junction of Woodward Road, about half a mile from the flyover. The tailbacks caused by these cause Lodge Avenue traffic to back on to the roundabout, and back on to the A13. Unless a solution to this is found, putting A13 traffic in conflict with this will just add further paralysis to the area. If they are going to just replace the flyover like for like, they will have to shut off Lodge Avenue during the work to stop the queues joining up.

[Scratchwood]

And it's worth noting that the plan is to move London's 3 commercial markets (Smithfield, Billingsgate and New Covent Garden) to a new site in Dagenham next to the A13, creating extra traffic for the area. There will be gridlock if they just remove the Lodge Lane flyover without a replacement.

[MotorwayGuy]

The Army and Navy Flyover in Chelmsford that was of a similar design was removed a few years ago due to structural concerns. I'm not sure how badly traffic has been affected but as they are not replacing it, it's obviously something that can be mitigated with junction improvements. Like has been said many of these low-capacity, isolated grade separations could be replaced with flat junctions but the Lodge Avenue flyover is the opposite of this. The flyover carries four lanes of traffic on a route that is (almost) grade seperated for miles on both sides. Knowing how bad traffic can be in this area, I dread to think what it would be like if all traffic was forced through the junction below. Of course there are other cases in London of flat junctions on an otherwise fully grade separate road, such as this (IMO ridiculous) junction on the A12 at Bow that used to be a LILO, and on the A2 at Kidbrooke. The latter generally copes well but is a simple signalised junction with only two phases.

[Runwell]

The Army & Navy junction regularly sees long delays on all approaches - nothing unusual, even when the flyover was there, but definitely worse since it was shut. Over time, traffic has generally found ways around it, and no doubt behavioral changes have taken place, e.g. working from home, changing journey times. The A12 heading from what was the Baddow bypass exit that led to the A&NF, queues most mornings all the way up to the Boreham exit, despite going against the general flow of traffic. Routes from the south of the city, such as the Stock Road, are taking much more of a hit as well. When the flyover closed, Essex Highways decided to replace all the signage through the city and outskirts and almost erase any locations from the map completely, in an effort to manupulate traffic flows. Quite an undertaking. Whether it has the intended effect, only they can answer that.


As for Lodge Avenue, as per previous posts, having all A13 traffic use the roundabout, even if there is some temporary reconfiguration, is a quite horrendous thought. However, time is ticking for the life of the flyover. It's often been the subject of numerous overnight closures to polish the turd. Even these have caused horrific queues very late at night, so the thought of that being a permanent situation during the day doesn't bear thinking about.

[WHBM]

We know now that a properly designed signalised intersection can handle far more traffic than the discredited roundabout. We should therefore provide a proper high-capacity signalised intersection, and save ourselves the cost of a new flyover.

That's not necessarily true; it depends on the flows, available width, specific geometry, pedestrian flows, and more particularly the number of legs to the roundabout and the right-turning component, which absorbs the most capacity. You need to do the figures.

For A13 Lodge, the difficulty is that the two major intersecting roads are both on the north side; it is not a simple crossroads with parallel flows. The amount of traffic moving between these two major intersecting roads, Lodge Avenue and Ripple Road, particularly westbound where they have to thread under the A13 twice, is very low.

Even with the S4 flyover in "freeflow" the traffic merging 3 into 2 can back up for miles, eastbound in the evening peak, and westbound not only in the morning peak but well through the day.

[Runwell]

Ironically, the Barking & Dagenham Post is reporting today that the speed limit is being cut at the Lodge Avenue flyover, from 40mph to 30mph. From the description it looks like they are slightly extending the restriction on the A13, and on the slip roads, although, perhaps unsurprisingly for a gutted local title, no mention that the flyover has already been reduced to 30mph. Probably written by someone in a Newsquest hub in West London who's never been East of Tower Bridge.

[Peter Freeman]

For A13 Lodge, the difficulty is that the two major intersecting roads are both on the north side; it is not a simple crossroads with parallel flows. The amount of traffic moving between these two major intersecting roads, Lodge Avenue and Ripple Road, particularly westbound where they have to thread under the A13 twice, is very low.

Even with the S4 flyover in "freeflow" the traffic merging 3 into 2 can back up for miles, eastbound in the evening peak, and westbound not only in the morning peak but well through the day.

Since you're local, I respect your analysis, but here's mine -

1. It's not a simple cross-roads, agreed, but it is only 4-way, and occupies a significant area. A 4-way signalised non-rotary intersection could easily be designed and constructed there, even with the current flyover, and result in immediate benefit. A good signalised design would not require any route to double-pass below the flyover.

2. The roundabout congestion appears not particularly bad. GMaps traffic says that nearby congestion on each of the four roads has little to do with the roundabout - look a few hundred metres along each of those roads for the real causes (as you allude to yourself).

3. My suggestion that 1960's and 1970's 'temporary' flyovers were and are actually superfluous related to my examples Hogarth and Gallows. There are probably more, but I don't claim it for this location (though you never know).

4. Replacing this flyover, under traffic, would be difficult. All 6 lanes seem to be on the same steel structure, so perhaps one-side-at-a-time isn't feasible. The replacement would only need 4 lanes, not 6 - that was an extravagance. This might ease the process.

[ChrisH]

The reason that Lodge Avenue hasn't yet been replaced is the long-running disagreement between the authorities on what to do about it.

- The local authority wants to build loads of housing around here and bury the A13 in a tunnel to enable it.
- TfL doesn't want to build new structures and would quite like to demolish the flyover.
- RMS Ltd, the operator, is contractually obliged to replace and upgrade it.

[Bryn666]

The reason that Lodge Avenue hasn't yet been replaced is the long-running disagreement between the authorities on what to do about it.

- The local authority wants to build loads of housing around here and bury the A13 in a tunnel to enable it.
- TfL doesn't want to build new structures and would quite like to demolish the flyover.
- RMS Ltd, the operator, is contractually obliged to replace and upgrade it.

Given it's grade separated either side, the obvious thing is to put it in an underpass and landscape around it so the housing is deliverable and not overlooking a miserable flyover but TfL Streets will need to be shown that you can have GSJs and cycling/walking infrastructure... the Dutch manage it. Slapping a random at-grade junction here would just be stupid design all round.

[Runwell]

For A13 Lodge, the difficulty is that the two major intersecting roads are both on the north side; it is not a simple crossroads with parallel flows. The amount of traffic moving between these two major intersecting roads, Lodge Avenue and Ripple Road, particularly westbound where they have to thread under the A13 twice, is very low.

Even with the S4 flyover in "freeflow" the traffic merging 3 into 2 can back up for miles, eastbound in the evening peak, and westbound not only in the morning peak but well through the day.

Since you're local, I respect your analysis, but here's mine -


2. The roundabout congestion appears not particularly bad. GMaps traffic says that nearby congestion on each of the four roads has little to do with the roundabout - look a few hundred metres along each of those roads for the real causes (as you allude to yourself).


4. Replacing this flyover, under traffic, would be difficult. All 6 lanes seem to be on the same steel structure, so perhaps one-side-at-a-time isn't feasible. The replacement would only need 4 lanes, not 6 - that was an extravagance. This might ease the process.

Lodge Avenue flyover is four lanes. There's a lane drop for the flyover.

From experience, the issues with the lights further up Lodge Avenue have often caused traffic to queue on to the roundabout, which then causes gridlock, with the traffic heading for Lodge Avenue blocking up circulation of the roundabout, which then backs on to both directions of the A13. Whether Woodward Road can be made no right turn from Lodge Avenue might help, perhaps a mini roundabout, although not sure if there was any previous layout to that junction?

[AnOrdinarySABREUser]

At the moment, I see three viable options at Lodge Avenue:

• The removal of the junction, A13 mainline widened to D3;
• The construction of a new D2 overpass;
• The construction of a new D2 underpass.

I don't see TfL selecting the underpass due to the higher price and complexity due to the earthworks, retaining walls and bridges TfL would have to do/build. However, it could be feasible for where improving the quality of the environment is more important than anything else, making the area more attractive for development. Conversely, the overpass and at-grade solution would be cheaper and less disruptive to build but both options depend on TfL's priorities too. If they wanted to spur new development and retain local access, then they would go with the overpass. If they wanted a cheap solution that prioritises strategic and regional movements then they would go with the at-grade solution.

[RichardA35]

At the moment, I see three viable options at Lodge Avenue:

• The removal of the junction, A13 mainline widened to D3;
• The construction of a new D2 overpass;
• The construction of a new D2 underpass.

I don't see TfL selecting the underpass due to the higher price and complexity due to the earthworks, retaining walls and bridges TfL would have to do/build. However, it could be feasible for where improving the quality of the environment is more important than anything else, making the area more attractive for development. Conversely, the overpass and at-grade solution would be cheaper and less disruptive to build but both options depend on TfL's priorities too. If they wanted to spur new development and retain local access, then they would go with the overpass. If they wanted a cheap solution that prioritises strategic and regional movements then they would go with the at-grade solution.

In studying the three "viable" options, it would be great if someone could explain where the existing flyover traffic would go and how the junction could be dealt with (without undue traffic chaos) during the construction period which would likely be much more than a year long (I reckon closer to 3 if an underpass) depending upon the option.
If the existing flyover is retained then the new flyover or underpass would be off line which would likely mean property acquisition or there would be a very complex staged construction that would take longer.

[Chris5156]

4. Replacing this flyover, under traffic, would be difficult. All 6 lanes seem to be on the same steel structure, so perhaps one-side-at-a-time isn't feasible. The replacement would only need 4 lanes, not 6 - that was an extravagance. This might ease the process.

It would be impossible - the structure is only just wide enough for the four lanes it carries (not six) and cannot be split in half. You either keep it or you demolish it.

[SouthWest Philip]

4. Replacing this flyover, under traffic, would be difficult. All 6 lanes seem to be on the same steel structure, so perhaps one-side-at-a-time isn't feasible. The replacement would only need 4 lanes, not 6 - that was an extravagance. This might ease the process.

It would be impossible - the structure is only just wide enough for the four lanes it carries (not six) and cannot be split in half. You either keep it or you demolish it.

There's nothing much of architectural value to the south of this junction. Industrial warehouses and business units are easily replaceable. Surely the least disruptive thing for traffic would be to take the A13 offline to the south and bypass the existing junction? This would also take the road further away from residential areas.

[AnOrdinarySABREUser]

<snip>

In studying the three "viable" options, it would be great if someone could explain where the existing flyover traffic would go and how the junction could be dealt with (without undue traffic chaos) during the construction period which would likely be much more than a year long (I reckon closer to 3 if an underpass) depending upon the option.
If the existing flyover is retained then the new flyover or underpass would be off line which would likely mean property acquisition or there would be a very complex staged construction that would take longer.

If the existing flyover is demolished during the construction period, then TfL could (1) remove access between the A13 and A123, (2) construct a temporary 2 lane EB carriageway for the A13 and (3) narrow the A13 to D2 where the existing flyover ends. The under/overpass would then be built along roughly the same alignment as the existing flyover.

If the existing flyover is retained during the construction period, then TfL could demolish the metal plant, pub and garage. The under/overpass would then be built to the north of the existing flyover, diverging into two viaducts/cuttings to make way for the EB onslip, which would be built underneath the existing flyover and come under the EB viaduct/cutting to rejoin from a normal position.

Ideally, all of these structures would be about the same length as the existing flyover.

To me, demolishing the existing flyover during the construction period would be a better choice since there would be no need to demolish or push up against properties adjacent to the existing A13. It would also be less complex to build and construct. You also have Movers Lane to the west of the existing junction which motorists can access.