Author Topic: Hammersmith flyover closed (Read 23059 times)

rogerzilla · « **Reply #25 on:** 30 December, 2011, 08:24:56 pm »

This was British workmanship, probably by the lowest tender.

It won't have been grouted properly.

LittleWheelsandBig · « **Reply #26 on:** 30 December, 2011, 08:28:39 pm »

Bridge decks get colder than the surrounding roads, so the gritters often crank up the volume as they traverse long bridges. Local authorities and the Highways Agency will grit roads with big bridges when they wouldn't grit roads without.

Bridges lead a hard life!

Cudzoziemiec · « **Reply #27 on:** 30 December, 2011, 10:15:21 pm »

Let's say the concrete itself is too corroded or the cables cannot be replaced for some reason, and the flyover needs to be demolished and rebuilt - I wonder, will they rebuild it to the same design, or will they maybe work out some ground-level road design to take similar traffic volumes?

Andrij · « **Reply #28 on:** 30 December, 2011, 10:41:00 pm »

Can anyone 'local' do a recce to see if it's possible to get onto the bridge (on a bike, of course)?

If Yes (and my lurgy is gone) I'll give it a go on 2 January. Even if no one can recce, I may still head out to take a look.

Anyone else interested?

Cudzoziemiec · « **Reply #29 on:** 30 December, 2011, 11:10:24 pm »

Interested? Yes.
Around on 2nd January? No.
I'll have to make do with memories of the Koramangala-Indiranagar flyover instead.

Jurek · « **Reply #30 on:** 31 December, 2011, 06:31:10 am »

Thanks for the info LWAB & Matthew.
Matthew - your link is 'subscription only'

LittleWheelsandBig · « **Reply #31 on:** 31 December, 2011, 06:41:04 am »

Replacing a major road bridge is very rare, particularly in a built-up area. No space and huge costs, they'll do everything they can to strengthen the old one.

Removing/replacing strand from grouted ducts is not trivial, much easier with greased ducts, as is common in the USA (but they have other problems).

Concrete doesn't corrode but steel in the concrete can. The high-strength steels used for PT are particularly prone to corrosion and tends to be damaged by cathodic protection.

My uninformed guess is that the reinforcement is generally corroding and that they are replacing chloride-impregnated concrete and corroded reinforcement. As they were doing so, they found excessive damage to the PT anchorages/ ducts/ strands and the scope of work has got much bigger and more expensive. Not uncommon to find things are worse than appears on the surface.

rogerzilla · « **Reply #32 on:** 31 December, 2011, 08:45:55 am »

Quote from: Cudzoziemiec on 30 December, 2011, 10:15:21 pm

Let's say the concrete itself is too corroded or the cables cannot be replaced for some reason, and the flyover needs to be demolished and rebuilt - I wonder, will they rebuild it to the same design, or will they maybe work out some ground-level road design to take similar traffic volumes?

Whatever is cheapest, probably, so I can see a non-elevated solution. Is there anything expensive underneath?

Jurek · « **Reply #33 on:** 31 December, 2011, 08:47:28 am »

Quote from: rogerzilla on 31 December, 2011, 08:45:55 am

Whatever is cheapest, probably, so I can see a non-elevated solution. Is there anything expensive underneath?

Hammersmith gyratory.
Well... half of it anyway.

LittleWheelsandBig · « **Reply #34 on:** 31 December, 2011, 09:04:29 am »

Without a flyover, traffic capacity is significantly reduced. That is why they built the bridge in the first place. Traffic has increased since it was built.

matthew · « **Reply #35 on:** 31 December, 2011, 11:34:57 am »

Quote from: Jurek on 31 December, 2011, 06:31:10 am

Thanks for the info LWAB & Matthew.
Matthew - your link is 'subscription only'

Sorry Jurek, google nce and hammersmith flyover, it wasn't subscription only via that route only by the direct link.

Jurek · « **Reply #36 on:** 31 December, 2011, 11:55:21 am »

Thanks Matthew.
Interesting to read in the comments: 'Will Westway be next?'

matthew · « **Reply #37 on:** 31 December, 2011, 12:13:12 pm »

Order of construction was Chiswick flyover (different design type), Hammersmith Flyover, Westway. All built in the late 1950s to late 1960s and probably had 40 year design lives (about normal for reinforced concrete at the time) new structures probably have 75 year design lives specified.

All three structures are therefore probably 'due' for replacement but due to the cost and difficulty will be 'managed' and 'maintained' to extend their usable life. e.g. lower speed limits to reduce live loads and weight restrictions to reduce dead loads in the event of stationary traffic.

rogerzilla · « **Reply #38 on:** 31 December, 2011, 12:43:37 pm »

Ok...who's ridden all of them on a bike?

sas · « **Reply #39 on:** 31 December, 2011, 02:16:08 pm »

Quote from: matthew on 31 December, 2011, 11:34:57 am

Sorry Jurek, google nce and hammersmith flyover, it wasn't subscription only via that route only by the direct link.

Alternatively you can find the description of the design here (it's copied and referenced by the NCE article):
http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=1164

nicknack · « **Reply #40 on:** 31 December, 2011, 02:42:42 pm »

Quote from: rogerzilla on 31 December, 2011, 12:43:37 pm

Ok...who's ridden all of them on a bike?

Westway? That would be interesting.

Yes to the other two.

rogerzilla · « **Reply #41 on:** 31 December, 2011, 03:50:26 pm »

Quote from: nicknack on 31 December, 2011, 02:42:42 pm

Quote from: rogerzilla on 31 December, 2011, 12:43:37 pm
Ok...who's ridden all of them on a bike?
Westway? That would be interesting.

Terrifying, actually, especially in the dark on a Brompton.

matthew · « **Reply #42 on:** 31 December, 2011, 03:52:49 pm »

Quote from: nicknack on 31 December, 2011, 02:42:42 pm

Quote from: rogerzilla on 31 December, 2011, 12:43:37 pm
Ok...who's ridden all of them on a bike?

Westway? That would be interesting.

Yes to the other two.

Well done, chiswick flyover is the M4

At least west way is no longer the A40(M) it lost the M when it was handed over to TFL to operate.

rogerzilla · « **Reply #43 on:** 31 December, 2011, 04:10:27 pm »

There are still "no cycling" signs for Westway, but if there is one on the Gloucester Terrace slip, I missed it.

nicknack · « **Reply #44 on:** 31 December, 2011, 05:00:54 pm »

Quote from: matthew on 31 December, 2011, 03:52:49 pm

Well done, chiswick flyover is the M4

Oops!

Was thinking of the flyover on the Hogarth Roundabout.

Jurek · « **Reply #45 on:** 31 December, 2011, 06:34:14 pm »

Both Hammersmith Flyover and Westway have cycling and pedestrians prohibited signage on their eastbound carriageways.

I've seen no evidence of the same on the westbound side.

matthew · « **Reply #46 on:** 01 January, 2012, 12:50:52 am »

I've ridden hammersmith west bound, there were signs say not suitable for cyclists but no actual prohibition and I felt happier going over the top than round a gyratory i didn't know.

The hogarth flyover is a temporary structure built in the 70s or 80s which motor cycles are band from due the nature of the side barriers and the likelihood of ice.

nicknack · « **Reply #47 on:** 01 January, 2012, 10:44:46 am »

Quote from: matthew on 01 January, 2012, 12:50:52 am

The hogarth flyover is a temporary structure built in the 70s or 80s which motor cycles are band from due the nature of the side barriers and the likelihood of ice.

1969.

clarion · « **Reply #48 on:** 01 January, 2012, 02:01:08 pm »

Forgive my ignorance, but where is the hogarth?

And what implications are there for other large flyovers, such as the M6?

Jurek · « **Reply #49 on:** 01 January, 2012, 02:05:48 pm »

Quote from: clarion on 01 January, 2012, 02:01:08 pm

Forgive my ignorance, but where is the hogarth?

And what implications are there for other large flyovers, such as the M6?

It's the roundabout between Hammersmith flyover / gyratory and the start of the M4. By the Fullers brewery.
Single lane, eastbound, meccano construction.
Taking a flatbed car transporter + trailer over it is an *interesting* experience.
Not one I'd recommend.