Highest point on a motorway in Ireland

Kermit.de.frog

Tried to start this thread the other night but must have been server schenadigans... anyhow...

I stumbled across the highest point in metres above sea level on any motorway on the island of island and it surprised me somewhat.

Can you work out where it is?:)

I ain't tellin, yet :cool:

But i'll tell you when your wrong :pac:

OldMrBrennan83

Somewhere on the M9?

Kermit.de.frog

Nope

OldMrBrennan83

Only other one springs to mind (as being undulating, so probably too obvious) is south of Roscrea on the M7.

Wildly Boaring

M7 goes up and down a lot before birdhill.

Along there?

Wildly Boaring

Patww79 wrote: »

Only other one springs to mind (as being undulating, so probably too obvious) is south of Roscrea on the M7.

Snap

marno21

M8 between Mitchelstown and Fermoy ?

Kermit.de.frog

Nope to all.

It's above 250 meters though which is quite high! It's higher then Bray Head and Howth for example...

cml387

marno21 wrote: »

M8 between Mitchelstown and Fermoy ?

I know that Watergrasshill is actually higher than the Mitchelstown/Fermoy section.

Wildly Boaring

Watergrasshill?

vandriver

Following!

stampydmonkey

M11 around rathnew?

nim1bdeh38l2cw

I concur with Watergrasshill

TheRiverman

M1 north of the Boyne bridge.
.

TheShow

M8 around Cahir?

fergus1001

fair oul climb between knocktopher and Waterford could be there ?!

Victor

I'm guessing the top of the canopy at the toll plaza in Watergrasshill.

antodeco

I was thinking somewhere along the M2!

Kermit.de.frog

Ah nuts. Was expecting it to go a little longer.

Ok

https://www.viamichelin.ie/

Zoom in to Ireland. Click on "Type of map" on the right hand side of the map. Switch to "Outdoors".

The highest point on any motorway in Ireland is...at Watergrasshill interchange.

On the interchange at the slips south are at just over 250 meters.

I could be wrong, but I didn't come across anywhere else...and I looked because i'm that sad Like I say - I could be wrong - it's a good map you can check out yourselves!

The winners get a cookie

prunudo

My map is saying only 180m at Watergrasshill, 190m near Roscrea.

tayto lover

At Tullyesker on the M1 north of Drogheda.

Kermit.de.frog

jvan wrote: »

My map is saying only 180m at Watergrasshill, 190m near Roscrea.

Are we really going to take away Watergrasshill's only claim to fame so soon after we granted it to them? :pac:

I'll go with the viamichelin here - 250m at Watergrasshill tbh.

prunudo

Kermit.de.frog wrote: »

Are we really going to take away Watergrasshill's only claim to fame so soon after we granted it to them? :pac:

I'll go with the viamichelin here - 250m at Watergrasshill tbh.

I was using the curser on viewranger which uses open street maps. I zoomed in and can see the 250m contour now, must be a glitch in the software, apologies to you and Watergrasshill

hans aus dtschl

I know it's not exactly the peak of a mountain, but it's pretty exposed up there.

It seems there's snow up there when there's none anywhere else for miles around. It's not only high up but catches all the weather systems from North and South

CrankyHaus

How reliable and up to date is the Michelin map?

A quick look on Streetview shows the motorway at that point some height below the surrounding terrain, yet the contours indicate the very opposite.

I suspect it's old map data that does not take into account the motorway construction and its effect on the local topography.

Of course 200 m would still put it above anything else on the thread.

xabi

Does Belfast count? Top of the M2

nim1bdeh38l2cw

xabi wrote: »

Does Belfast count? Top of the M2

Highest != Most Northerly

L1011

Janelle Wailing Boardroom wrote: »

Highest != Most Northerly

That isn't the most Nothernly - the Ballymena Bypass is.

There is a very significant hill heading out of Belfast on the M2; however it doesn't seem to be as high as the M8 example

Aontachtoir

L1011 wrote: »

That isn't the most Nothernly - the Ballymena Bypass is.

There is a very significant hill heading out of Belfast on the M2; however it doesn't seem to be as high as the M8 example

The A8(M) on the Larne road goes up even higher, if I remember correctly.

Victor

Aontachtoir wrote: »

The A8(M) on the Larne road goes up even higher, if I remember correctly.

Approximately 160 metres altitude: https://www.openstreetmap.org/#map=16/54.6882/-5.9732&layers=C

xabi

Janelle Wailing Boardroom wrote: »

Highest != Most Northerly

You don’t say!

csd

This question interested me, so I thought of a way of doing this analysis using publicly-available GIS data.

1. NASA has made the radar data from the Space Shuttle Topography mission freely available
2. OpenStreetMap data for the motorway network is available for download

The SRTM data gives an elevation figure for 55 x 90 metre sized tiles across Ireland, and point data for the motorway network can be extracted from the OSM data. Combining the two gives us an elevation figure for each motorway segment in the network.

This gives us three points on the network where the elevation is 180 metres or higher:

1. On the M7, 194 metres elevation, 360 metres west of km marker 120.5 on the M7, between J22 and J23
   M7 highpoint
2. On the M8, 183 metres elevation, just north of km marker 105, between J13 and J14 near Kilworth
   M8 high point
   
3. On the M8, 180 m elevation, at the Watergrasshill exit

Looking at Watergrasshill, those contours have to be wrong. The image below shows the general area with contours extracted from the SRTM data. The two insets show the Google Street View, looking south from roughly the centre of the interchange, and the contours that Via Michelin and the OSM HikeBike map use. The terrain looks far more like the SRTM contours than the ViaMichelin/OSM ones. If the latter were correct, there'd be a 27% gradient between the interchange and the top of that 250 metre hill shown. As can be seen from the GSV shot, that just isn't the case.
Watergrasshill analysis - QGIS-3
/csd

csd

And if anyone's interested, the highest point on the National Primary network is between Ballyvourney and Clonkeen on the N22, where it reaches 297 metres.

/csd

Kermit.de.frog

Watergrasshill says no!

Victor

Part of this may be down to the map projection - the world isn't a perfect sphere and neither is zero altitude.

marno21

csd wrote: »

Looking at Watergrasshill, those contours have to be wrong. The image below shows the general area with contours extracted from the SRTM data. The two insets show the Google Street View, looking south from roughly the centre of the interchange, and the contours that Via Michelin and the OSM HikeBike map use. The terrain looks far more like the SRTM contours than the ViaMichelin/OSM ones. If the latter were correct, there'd be a 27% gradient between the interchange and the top of that 250 metre hill shown. As can be seen from the GSV shot, that just isn't the case.

/csd

I thought this too but I wasn't arsed researching it. The contours show the top of the hill as being at the interchange, whereas the interchange itself is in a shallow cutting. There's no way it's fully accurate around there.

hans aus dtschl

csd wrote: »

Looking at Watergrasshill, those contours have to be wrong. The image below shows the general area with contours extracted from the SRTM data. The two insets show the Google Street View, looking south from roughly the centre of the interchange, and the contours that Via Michelin and the OSM HikeBike map use. The terrain looks far more like the SRTM contours than the ViaMichelin/OSM ones. If the latter were correct, there'd be a 27% gradient between the interchange and the top of that 250 metre hill shown. As can be seen from the GSV shot, that just isn't the case.

/csd

I know the topography here particularly well: the SRTM contours look correct to me, it even has the subtle depression at the M8 S130 marker.