Sunday, October 13, 2013

The A34 Beedon Roadworks

The UK Highways Agency has written to 'stakeholders', informing them of impending roadworks on the A34, a busy, swooping dual-carriageway which passes between Newbury and Oxford.

The very use of that apostrophe-enclosed term should already forewarn the reader that we have entered the strange world of corporations and government agencies, a world dominated by liability transfer and reduction.

It transpires that the A34 runs over a bridge near a village called Beedon, and the bridge requires 'refurbishment'. Sadly, despite the miracles of modern engineering, it seems that the process will require not merely roadworks and speed restrictions on a small part of the A34, but the entire closure of both carriageways overnight, and throughout successive weekends.

Carol Hurley, Communications Manager of EM Highways Services Ltd, writing on behalf of the Highways Agency, claims that "these full weekend closures are required to ensure the safety of both the workforce and the travelling public, due to the nature of the activities to be undertaken."

Blimey. Sounds like they could be using rocket-propelled grenades as part of the 'refurbishment' process. It's just as well, then, that they're closing the road at the weekend, although I'm a tad concerned for the risks encountered by the public during a weekday rush-hour as, zig-zagging through the contraflow, they try to avoid being penetrated by a shaped explosive charge.

The good news, however, is that Ms Hurley is able to recommend a diversion: "For both the north and southbound closures the main strategic diversion route for motorway permitted vehicles will be via the M40, A404 and M4 - the distance is 46 miles and the expected delay times will be a minimum of 42 minutes."

A 46-mile 'strategic' diversion? A brief perusal of the map below displays the diversion which Carol has in mind. The roadworks are roughly equidistant between Chieveley and Chilton, labelled 'A' and 'B' in the figure. The M4 runs East-West along the bottom of the image, the A404 runs North-South up the right-hand side, and the M40 runs diagonally between High Wycombe and Oxford.

Perhaps it's best to fill up with a full tank of fuel before you attempt Carol's 'strategic' diversion.

Carol defensively states that "this route has been agreed by the local authorities, police authorities and other Highways Agency areas."

Which explains everything. There are plenty of routes either side of the A34 between Newbury and Oxford, but all of them are B-roads passing through small towns and villages. Understandably, they don't want their roads to be clogged up with the copious amount of traffic, much of it heavy freight, which travels along the A34. So despite the fact that these are exactly the diversionary routes which people will actually take, the Highways Agency and the police authorities don't recommend using them. If they did, they would be responsible for clogging up small roads, and possibly causing numerous accidents, and they certainly don't want to accept liability for something like that. No, what they do is to recommend a completely unfeasible diversion. If the motorists and truck-drivers ignore their recommendations, then that's outside their control; such motorists are clearly foolish and irresponsible, and must be the ones held to blame, not the Highways Agency or the police authorities.

Job done.


Unknown said...

Boilerplate UK...

Peter B said...

Hello Professor McCabe,
I already have the paper by Sovran and Klomp courtesy of my university library, but even they couldn't find the 1994 Sovran paper.

Anyways, I have more pertinent questions:

I'm a huge Formula 1 fan and I try to find as many academic publications as possible on Formula One aerodynamics. I find your blog very informative. I have two basic questions:

(1) Is the diffuser a "diffuser" in physical geometry and not in function ? I read in an issue of Bernoulli magazine that some F1 aerodynamicist said the diffuser is more like a wing with camber that curves the airflow causing a pressure gradient with the pressure lower inside the curvature and higher pressure towards the outside of the flow curvature. He further said this low pressure sucks the air from under the floor. He said 4/5 of the floor does nothing but make sure the flow gets to the diffuser where it is needed ? So is there only two low pressure peaks at the floor's leading edge and the the diffuser inlet ? If that is the case how does a longer floor give you more downforce (in particular I read a longer sidepod will give you more rear downforce, but how ) ?

(2) What is "clean" air and "dirty" air ? When is turbulence good or bad ? When is a vortex good or bad ? Is vortex shed from the tires always bad and why ? How does rear tire squirt negatively affect the diffuser ?

I realize this is a lot of questions, but I feel you are one of the few people qualified to answer this.

Thank you very much for taking the time to read this message.


Peter from Canada

Gordon McCabe said...

Cheers Peter.

I think the aerodynamicist in Bernoulli magazine was correct. But I don't know enough to say how the length of the floor influences downforce.

I think turbulence is always bad because it's chaotic vorticity on numerous different time and length-scales. Vortices with a single length and time-scale, with low levels of turbulence, can be good!