The Fragile Routes to the West of England - Wessex Sub Aqueanus

Over the last month, we have seen the fragility of the transport infrastructure through Wessex.  First we had the closure of the A303 in Somerset A303 between the Podimore and Cartgate Roundabouts on Christmas Eve when the River Yeo burst its banks.

Then we had a second closure of the A303, at the Deptford Junction with the A36, caused by rising groundwater levels on the western edge of Salisbury Plain.  Even after the initial flood subsided a wee bit, we still had a contraflow working for some time as it took some time for all carriageways and the slip roads to clear.  Even this week, the A303 westbound has been closed at night to allow the damage caused by the flooding to be repaired.

The rain has continued at a lower intensity for the last couple of weeks, and the A303 seems to be safe for the moment.  That said, groundwater levels haven't dropped at all on Salisbury Plain, even though the levels in the River Till, through Winterbourne Stoke have dropped around 5-10 cm.  Today, the Tilshead borehole levels look like this:

Of course, yesterday, we had yet more rain and storm surges throughout the Wessex region.  We had 14.7mm here in Winterbourne Stoke, but that was trivial compared to levels further West.  The Somerset Levels,  already suffering for over a month from the floods, exacerbated by the abject failure of the Environment Agency to effectively dredge blocked water channels, has water levels rising yet again.  King Canute couldn't hold back the water and sadly, it seems, neither can Prince Charles - but at least he took the time to go, showed REAL understanding of the issues and concerned for those he met.

The rain and the spring tides and high winds wrought damage further west in Dawlish, tearing out the ballast under the main line from Exeter to Penzance, ripping out the adjacent road and threatening houses and businesses.

This morning on  TV,  a Network Rail spokesman was suggesting that it might take 6 weeks and tens of millions of pounds, if not one to two hundred million pounds,  to put right the damage caused in an hour of nature at its most furious.  And still more rain and high winds are predicted in the coming days - with rain levels on high ground predicted to be up to 20-40mm per day - higher than anything we have seen this winter by a good margin.

This all raises a number of very important questions for the Wessex transport infrastucture.  We have lost the major rail line for a number of weeks - assuming there is no further damage.  Passengers and freight are going to have to transfer to the roads - the A303 and the M4/M5 further north.  With the additional predicted rain, there seems to be a possibility that further flooding of the A303 might occur this weekend or early next week - pushing all that traffic on to the northern route.  

Engineers talk of a "single point of failure" (SPOF!), which is the part of a system, that if it fails, will cause the rest of the system to fail.  With multiple means of transport through Wessex, there was no SPOF, but it is possible that within hours or days, there will only be one point in the transport infrastructure left and only one to fail - the M4/M5 corridor.  A single minor incident on the motorway could stop traffic in any numbers getting through Wiltshire/Avon and in to Devon and Cornwall. Diversionary routes south through the Somerset levels are simply not viable.

I hope politicians locally and nationally are looking at this and thinking of the consequences.  In our campaign to improve the A303 west from the Hampshire border, we are often told that it will be the economic case that decides whether the A303 is improved,  rather than providing yet more roads/extra carriageways  in urban areas.  Somerset Council are pretty much on the ball and have made an excellent financial case for improving the A303/A358/A30 corridor.  Wiltshire Council seem to be riding very much on their coat tails - or worse.  Their level of engagement and activity has been described to me in very graphic terms:  "Thumbs up bums - brains in neutral!"  Certainly, trying to get a response from those with a transport brief on the Council is nigh on impossible - Wiltshire Council - where people mutter.

Perhaps Mother Nature has done us a major service by pointing out the real economic issues involved here.  From Stonehenge westwards along the whole of the A303/A358/A30 corridor, tourism is the major industry - and to take advantage of tourism, there is one over-riding priority - to get the tourists to the places they want to visit.  No means of the tourist getting there, no tourism.  No tourism, no jobs.  No jobs - no economy.

To support the tourism, goods need to be shipped in.  No rail and no road, no goods shipped in.  No goods, no tourists, no employment, no economy.  And, of course, everything that goes in has to get out again - along the same. limited routes.

For the Wessex region, it really is that simple - the transport infrastructure is its life blood - and with so few alternatives, it really is a unique situation that must be addressed as such.  Perhaps even Wiltshire Council can be encouraged to de-digitate and get on with it!

The A303 Ship Canal

Shortly before Christmas, the A303 responded to the intense rainfall by flooding near Yeovil, between the Cartgate and the Podimore Roundabouts.  For a couple of days, an Amphicar or another amphibious vehicle would have proved an absolute godsend to those wishing to travel along the A303.

Now, just over a week into the New Year and the same thing has happened again, this time a bit nearer to us at the A36 interchange.  Fortunately only on the eastbound carriageway and as I write, the Highways Agency are predicting it will be opened by 1800.  Time will tell - they do tend to err on the side of total unreality.

That got me thinking about the impact of floods and flooding on any A303 improvement scheme that might be put forward.  Clearly, flooding is becoming increasingly common with the effects of global warming, so we ought to expect that the Environment Agency ought to be one of the stakeholders for the forthcoming A303 feasibility study.  Someone else for us to talk to.

One of the plans put forward for a bypass of Winterbourne Stoke a few years since, had  the route of the A303 diverted north of the village, towards Shrewton.  It ran across the flood plain of the River Till, raised on a large earthwork berm.  Think dam -with a gap in it.  Now the River Till is normally a very benign little stream, but it hides a dark and dangerous secret - the Great Till Flood of 1841.

So notorious is that event, as an example of chalk downland groundwater flooding, that it is taught as an example of this phenomenon in universities around the world.  Events in 2014 are following a remarkably similar pattern to those in the January of 1841 - a period of heavy rain, with cold, possibly freezing weather in the next week.   At the moment, the Environment Agency have the following flood alert in place:

When you look at the water level in the Tilshead borehole, the aquifer that may be responsible (I'm speculating here, I'm not a hydrologist) for the flood on the A303 today, you will see why the idea of building the A303 on a berm might need looking at.

 It seems we are less than 0.5 metre from having an "interesting" situation.  I guess the next 4 or 5 days, with more rain forecast on Sunday, could prove interesting indeed for traffic on the A303.

Let's keep fingers crossed that the rain stops, the ground doesn't freeze, we don't have snow followed by a quick thaw and the water level in the aquifer drops - that way the A303 through Winterbourne Stoke might stay open.  Imagine though, for a moment, what might happen if the Great Flood of 1841 was repeated when the Till valley was largely blocked by a berm? 

Routing a new dual carriageway has many more things to consider than just the World Heritage site at Stonehenge.

 UPDATE: 

The Highways Agency have announced that the A303 (eastbound) is likely to remain closed at the A36 Deptford interchange all day today.  Great joy!

At 09:00 on Friday 10/01/2014, the water levels had crept up to 99.71 metres AOD (AOD - Above Ordnance Datum - or to you and me, above the mean sea level determined for the Ordnance Survey), which is just a smidgen below the highest astronomical tide level for this site, which is 99.88 m AOD.

Anyone wanting to learn more about the Great Flood of 1841 might want to read a paper called "Estimating Extreme Floods".   It was written by by Colin Clark in 2004 and published in a journal with the catchy title of:  International Water Power and Dam Construction.  You couldn't make this stuff up, could you!

Despite the turgid sounding nature of this paper, it is a surprisingly good and thought provoking read.

A303 - The Highway to Hell

It is Monday 30th December 2013.  It is raining heavily, 10mm already this morning, and it is blowing a gale; though not as bad as it was a week ago in the run-up to Christmas.  The great New Year exodus will begin today, with folks travelling east and west along the A303.  Of course, minds will be a little more focused than they were last week, particularly in relation to the flooding of the A303 between the Podimore and Cartgate Roundabouts in Somerset.

At the moment, Cartgate looks like this:

and Podimore looks like this:

The weather does look to be clearing a bit from the West, so there is some hope the rain will stop - at least for a while.


But if the traffic gets bad and you get stuck on the A303, what can you do to pass the time?  Well, how about a bit of karaoke?  What better track to sing along to than AC/DC's Highway to Hell.  It sort of sums up the A303 experience at the moment.  Enjoy:

A Merry Christmas - Tales from the A303

Well, if you have tried to travel along the A303 over the Christmas period, you have been enjoying anything but festive fun.

Apart from the usual traffic chaos caused by too much traffic trying to squeeze its way from the dual carriageway east of Amesbury on to the single and 3-lane carriageway sections from Stonehenge westwards, we have had to contend with the unpredictability of Mother Nature and everything she could throw at us in the way of rain. 

23rd December 2013 brought torrential rain and gales.  Several folks attempting to negotiate the A303 described the conditions as the worst they have ever encountered in over 25 years - that says something about the nightmarish time many folks had.  We decided that rather than pushing the campaign too hard, we would try and be helpful to those unfortunate enough to have to travel - so we spent the day listening to the radio, watching the Traffic England website and the traffic cameras and tweeting (See @rural warrior) using the #A303 hashtag.

Things couldn't get any worse - could they?

Well, on Christmas Eve, there were several problems.  A multi-car pile-up and oil spill to the east of Winterbourne Stoke near Amesbury caused westbound chaos, the A36 had its own problems, as did many of the minor roads and then...

...then the River Yeo burst its banks between the turnings for the A37 and the A3088 in Somerset and flooded the A303.  Result - traffic hell.

Well, drivers did what they always do in such circumstances and took the first diversionary route they could - straight in to more floods on the A37 and the A359.  Journeys that should have taken minutes were taking several hours.

Thankfully, those problems have resolved...

...at least for the moment.  The heavy rain predicted for today seems not to have materialised and we now have only light rain predicted for Monday.  That's a great relief for us here in Winterbourne Stoke.  At our local borehole in Tilshead up on Salisbury Plain the water level has risen 8 metres since Christmas Eve.  That's right, 8 metres in three days.  If we have a similar amount of rain to that we had on the 23rd in the next few days, then we could have springs breaking around the local villages a good month or two early and the risk of high land flooding.   Did you know that this part of the world is infamous for its floods - you'd never have thought of that on Salisbury Plain - but the Great Till Flood of 1841 is so notorious that many universities worldwide study it.

We'll keep an eye open to the weather for the next few days...

...just in case.  Then back to the campaign for 2014!