YorkshireBear
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As we all knew from childhood :
The irony of this video of course is that there is an actual active landslip on the opposite side of the line there at the KWVR.
As we all knew from childhood :
But as has been shown by several posters since, the posting by kristiangl85 was incorrect.
Trees cover the slopes of many railway earthworks supporting the United Kingdom’s transport network. Root water uptake by trees can cause seasonal shrinkage and swelling of the embankment soil, affecting the line and level of the railway track. This requires continual maintenance to maintain the serviceability of the track and reduce train speed restrictions. However, the removal of trees from railway embankment slopes and the loss of soil suctions generated by root water uptake may negatively impact embankment stability, particularly during periods of wet weather. An improved understanding of the influence of tree removal on embankment hydrology is required so that infrastructure owners can develop a managed system of vegetation clearance.
Hydrological field monitoring data from an instrumented railway embankment are presented and compared with a finite element model of root water uptake incorporating daily weather data. It is shown that trees maintain persistent suctions within their root zone which are unaffected by seasonal wetting and drying at the soil surface. However, the removal of trees from the embankment slope causes wetting of the soil from the soil surface as persistent soil suctions within the root zone are lost.
Well, the paper I posted above argues to the contrary. Sorry, I should have pasted the abstract:
All that actually says is more research is required into the implications of removing trees. The Geotechnical engineers I know, including the one responsible for the whole of the SE of England, are unequivocal that trees are not good for earthworks, and need to be removed where possible.
I mean I'm only going off my own experience of studying effects of deforestation on erosion patterns (yay for studying geography); yes this is smaller scale and quite different, but the science is broadly the same. Ultimately we are messing about with nature by building the railways through these areas, and to me cutting them down is just too simplified a solution. As has been said, the root systems do lead to instability, and a dead root system is even worse.
Maybe more can be done to look at species with less invasive root systems on the railway structures and re-planting with these. I personally believe full on clearing of vegetation will lead to more land slip issues. And, given how many have happened since the tree cutting programme, which seem to my untrained eye more than normal, this is something that needs to be looked at with urgency.
The tree cutting programme has been in place for as long as I’ve been on the railway (getting on for 30 years) and no doubt longer than that! It’s just recently been in the news, that’s all.
I can sssure you u that the effects of trees on earthworks has been looked at in some detail by the Geotechnical engineers. And they want them out. Special action is taking to improve slope stability at the same time, if required.
It is of note that the very first thing that was done at Epsom following the slip there earlier this week was to remove all the vegetation in the area.
It's not called sand tunnel for nothing.Overhead view of Guildford landslip on BBC1 6pm National News, about 13 mins in. (Should become available for rest of today on iPlayer). Looked like an orange army digging by hand - embankment is all sand there.
I seem to recall that, following a significant embankment re-build between Worcester Park and Stoneleigh about 12-15 years ago, the ground was seeded with grass and wild flowers. Basically, lawns on sloping surfaces bind the ground but don't disturb anything beneath the surface, and protect the soil from runoff.
So you know which end of the tunnel it was? The end cloestyto Guildford Station is viable from a private road.The landslip is outside St Catherines Tunnel which is the southern tunnel outside Guildford.
In other news a 458 hit a car on a level crossing at Wokingham last night, car driver arrested on suspicion of drink driving.
Perhaps they should do that everywhere. Would that be possible?I seem to recall that, following a significant embankment re-build between Worcester Park and Stoneleigh about 12-15 years ago, the ground was seeded with grass and wild flowers. Basically, lawns on sloping surfaces bind the ground but don't disturb anything beneath the surface, and protect the soil from runoff.
So you know which end of the tunnel it was? The end cloestyto Guildford Station is viable from a private road.
I always thought the sand face was just too steep. Seems it’s almost bound to be washed out any time there’s serious rainfall. I bet it wouldn’t be built like that if they were to start again...Yes, south end of the sand tunnel. The north tunnel is the chalk tunnel and the south tunnel is called the sand tunnel, we are taught in our route learning that the way to remember it is that the sand tunnel is nearest the beach!
I always thought the sand face was just too steep. Seems it’s almost bound to be washed out any time there’s serious rainfall. I bet it wouldn’t be built like that if they were to start again...
If any one has an interest in reading up on managing railway earthworks this is a good read. https://www.railengineer.co.uk/2012/03/16/managing-earthworks/
Trees hold up banks – don’t they?
Vegetation has an important influence on earthwork behaviour. Contrary to common belief, trees do not hold up the banks.
Whilst this may applicable to natural slopes or engineered highways earthworks, it is not applicable to the over-steepened cutting and embankment slopes on the railway infrastructure. Field trials on clay cored embankments have demonstrated ground disturbance to be 10 times greater where trees are present compared to grass.
What kind of work would be involved to stabilise the area around the south of the tunnel?
This doesn't happen often but of course if its frequency is likely to increase or it occurring recently makes it more likely to occur again then I guess it can't be ignored. Assuming something could be done that is.Not that easy, there's only 500 yds between the tunnel portal and Shalford Junction and this includes two roads going under the railway.
I'm astonished to learn that tree roots typically go down only five times as deep as grass roots. I'd have guessed far more than that.If any one has an interest in reading up on managing railway earthworks this is a good read. https://www.railengineer.co.uk/2012/03/16/managing-earthworks/
I'm astonished to learn that tree roots typically go down only five times as deep as grass roots. I'd have guessed far more than that.