N7 - Newlands Cross upgrade

RichardoKhan

Can anyone shed any light on why other than aesthetics one side underneath the bridge is straight down & the other sloped? Just curious if there is a possible technical/structrual reason.

smokie72

I think it was mentioned in another post that they want to leave enough room for a possible metro/luas line in the future.

JupiterKid

Great pics Smokie72. Looks like it's making great progress.:)

L1011

Metro West, if it ever happens, will run under it; they clearly don't want to have to re-do the bridge in that case.

lovelyhurler

This has probably been asked before as well, but why cannot we put roads (flyovers) on stilts, instead of all that banking?
Like Richard said - is there a structural/technical or economic reason for it?

L1011

lovelyhurler wrote: »

This has probably been asked before as well, but why cannot we put roads (flyovers) on stilts, instead of all that banking?
Like Richard said - is there a structural/technical or economic reason for it?

Maintenance costs more than anything else.

hi5

lovelyhurler wrote: »

This has probably been asked before as well, but why cannot we put roads (flyovers) on stilts, instead of all that banking?
Like Richard said - is there a structural/technical or economic reason for it?

If you ever drove over this thing in East London, you'd know why.

The only consolation was that so many are afraid to drive over it that you have it all to your self sometimes.

https://www.google.ie/maps/@51.5925663,0.2129779,3a,75y,270h,90t/data=!3m4!1e1!3m2!1sQd5ghY0smeGowyz4AoYDKA!2e0

serfboard

hi5 wrote: »

If you ever drove over this thing in East London, you'd know why.

The only consolation was that so many are afraid to drive over it that you have it all to your self sometimes.

https://www.google.ie/maps/@51.5925663,0.2129779,3a,75y,270h,90t/data=!3m4!1e1!3m2!1sQd5ghY0smeGowyz4AoYDKA!2e0

There's one like that in Liverpool as well. An awful shaky experience driving over it.

ukoda

hi5 wrote: »

If you ever drove over this thing in East London, you'd know why.

The only consolation was that so many are afraid to drive over it that you have it all to your self sometimes.

https://www.google.ie/maps/@51.5925663,0.2129779,3a,75y,270h,90t/data=!3m4!1e1!3m2!1sQd5ghY0smeGowyz4AoYDKA!2e0

How do they make this work so well in the US tho? they have most of their highways and junctions in the cities up on raised roads.

Carawaystick

lovelyhurler wrote: »

This has probably been asked before as well, but why cannot we put roads (flyovers) on stilts, instead of all that banking?
Like Richard said - is there a structural/technical or economic reason for it?

I'd say there's a big economic reason, concrete stilts need cement, rebar
Then they need to be designed for the load, beams again need to take the load
They will also have a more limited lifetime, due to the small dynamic loading and unloading.

Basically putting it on stilts is increasing the length of the "bridge" and bridge lengths are generally minimised

hi5

hi5 wrote: »

If you ever drove over this thing in East London, you'd know why.

The only consolation was that so many are afraid to drive over it that you have it all to your self sometimes.

https://www.google.ie/maps/@51.5925663,0.2129779,3a,75y,270h,90t/data=!3m4!1e1!3m2!1sQd5ghY0smeGowyz4AoYDKA!2e0

ukoda wrote: »

How do they make this work so well in the US tho? they have most of their highways and junctions in the cities up on raised roads.

That flyover was a "temporary" structure when it was built in the 1960s as there were (now abandoned) plans for a completely different road layout.

The US ones are likely to be designed to be earthquake resistant.

spacetweek

Cap1 wrote: »

I heard today.The first cars will be over the bridge on the October bank holiday.

Yep, I know someone in Clondalkin who got a notice in the door saying the same.

spacetweek

rameire wrote: »

it is that wide as it will also accommodate at some time in the far future, the Metro.

Yep that's it.

ukoda

spacetweek wrote: »

Yep that's it.

and does anyone know why the western side wall under the bridge is sloped outwards, while the wall on the east is a normal straight wall

if that makes sense

spacetweek

lovelyhurler wrote: »

This has probably been asked before as well, but why cannot we put roads (flyovers) on stilts, instead of all that banking?
Like Richard said - is there a structural/technical or economic reason for it?

That's called a viaduct and they look awful, create dark areas that attract litter and crime, and are a huge maintenance cost.

L1011

ukoda wrote: »

and does anyone know why the western side wall under the bridge is sloped outwards, while the wall on the east is a normal straight wall

if that makes sense

Same answer - due to the Metro. Sloped is easier to do if you've got the space but it won't work for the Metro obviously.

endacl

ukoda wrote: »

and does anyone know why the western side wall under the bridge is sloped outwards, while the wall on the east is a normal straight wall

if that makes sense

It's a buttress. Support.

ukoda

endacl wrote: »

It's a buttress. Support.

ah ok, but its kind of hollow at the moment, i assume they'll fill it in at some stage so

Chris_5339762

Carawaystick wrote: »

I'd say there's a big economic reason, concrete stilts need cement, rebar
Then they need to be designed for the load, beams again need to take the load
They will also have a more limited lifetime, due to the small dynamic loading and unloading.

Basically putting it on stilts is increasing the length of the "bridge" and bridge lengths are generally minimised

Also, the areas underneath them are havens for antisocial behavior and look far, far worse than an embankment.

Geogregor

MYOB wrote: »

Maintenance costs more than anything else.

Carawaystick wrote: »

I'd say there's a big economic reason, concrete stilts need cement, rebar
Then they need to be designed for the load, beams again need to take the load
They will also have a more limited lifetime, due to the small dynamic loading and unloading.

Basically putting it on stilts is increasing the length of the "bridge" and bridge lengths are generally minimised

Chris_5339762 wrote: »

Also, the areas underneath them are havens for antisocial behavior and look far, far worse than an embankment.

Like Carawaystick I also think decision was made mostly based on the construction cost.

Sure there are maintenance costs there but most of them are related to fixing surfaces, lighting, drainage or signage and you have to do it on the embankments too.

The concrete bridge structure itself doesn't require that much maintenance.

As for antisocial behavior, in such windswept location it probably wouldn't be a major problem. Most of the problems like that occur closer to the inner cities.

BTW, how about lifespan of this reinforced embankments?
There are metal strips in the soil holding the walls. At least I hope they are made of stainless steel.

Those reinforced embankments are used for last, what 20 years? I wonder how will they look in another 20-30 or 40 years. Will they be as long lasting as brick railway arches build by the Victorians?

Then, if problem occurs inside the embankment, how do you fix it?

Middle Man

Geogregor wrote: »

<snip>
Then if problem occurs inside the embankment, how do you fix it?

I guess when the embankment is old and crumbling, construction of cast-in-situ RC outer retaining walls - new piles would probably be required though...

markpb

ukoda wrote: »

How do they make this work so well in the US tho? they have most of their highways and junctions in the cities up on raised roads.

Several times a year I see traffic reports from Los Angeles where a major highway has been shutdown for hours because of a truck crash / truck fire at one of those flyovers. It's a big job to inspect it, repair any damage and get the road re-opened.

DeltaDev

Geogregor wrote: »

Like Carawaystick I also think decision was made mostly based on the construction cost.

Sure there are maintenance costs there but most of them are related to fixing surfaces, lighting, drainage or signage and you have to do it on the embankments too.

The concrete bridge structure itself doesn't require that much maintenance.

As for antisocial behavior, in such windswept location it probably wouldn't be a major problem. Most of the problems like that occur closer to the inner cities.

BTW, how about lifespan of this reinforced embankments?
There are metal strips in the soil holding the walls. At least I hope they are made of stainless steel.

Those reinforced embankments are used for last, what 20 years? I wonder how will they look in another 20-30 or 40 years. Will they be as long lasting as brick railway arches build by the Victorians?

Then, if problem occurs inside the embankment, how do you fix it?

The metal strips are galvanised steel, so no problem with them. The bridge and embankment are designed for a 120 year life. That should see most of us out!

TheJaff

I caught the tail end of a report on LiveDrive this evening and they were mentioning more lane changes for both inbound and outbound this weekend. Anybody have any details?

DeltaDev

DeltaDev wrote: »

The metal strips are galvanised steel, so no problem with them. The bridge and embankment are designed for a 120 year life. That should see most of us out!

Most of us????

D Trent

[Deleted User] wrote: »

Most of us????

Am nobody told you?
Ok here goes.
Once you have been promoted to a Moderator on boards.ie, you automatically gain an extra 30 yrs lifespan.

You my friend are one lucky ba$tard

jd

D Trent wrote: »

Am nobody told you?
Ok here goes.
Once you have been promoted to a Moderator on boards.ie, you automatically gain an extra 30 yrs lifespan.

You my friend are one lucky ba$tard

I think he went for the coke and hookers instead.

Seriously though, they seem to be making good progress. I presume they'll be able to route some of the inbound traffic over the bridge by the October Bank Holiday weekend.

marmurr1916

ukoda wrote: »

How do they make this work so well in the US tho? they have most of their highways and junctions in the cities up on raised roads.

How do you widen a raised road? Much easier to widen a road built at ground level.

BuzzFish

TheJaff wrote: »

I caught the tail end of a report on LiveDrive this evening and they were mentioning more lane changes for both inbound and outbound this weekend. Anybody have any details?

Didn't hear but I wonder if they took note of a mail I sent to bam/NRA/Kildare co co.....

Good Morning.

Firstly, thanks for taking a minute to read this as I understand you must be very busy.

As a biker and car driver I travel through Newlands cross each morning and evening and to be honest the traffic management has been superb so far throughout the construction phase.
I do want to highlight one area though that I feel is extremely dangerous.
As traffic is heading toward the junction from the Naas side, there is a shift of traffic from Lanes 1,2,3 into Bus,1 and 2 respectively, with lane 3 being signed for Belgard road.
This is causing a huge problem for bikes filtering towards the junction at times of traffic backlog as car drivers are “diving” down Lane 3 and then cutting across to lane 2 in order to head for the City/M50. I’ve been caught 2-3 times (and missed being hit by a matter of inches) and I’ve seen many other bikes have this happen when in my car queueing.

I’d suggest that the lanes get remarked temporarily (as happening in previous phases of the construction) to guide/force traffic from L1 to Bus, L2 to L1 and L3 to L2… with some hatchings / bollards on entry to the Belgard Lane (L3) just after citrywest.

I understand these things need planning and time but in the overall scheme I honestly think we could avoid a serious collision and also many “road rage” incidents that are happening as drivers skip the queue by using the Belgard land and cutting back in suddenly in front of queueing drivers.

Many Thanks and I appreciate your consideration.

TheScoringGoal

I cant remember the specifics but basically the outbound bus lane is going to be removed and a re-jig will mean that there will be an inbound bus lane instead