Materials Man

Our, not design and build,  A7 project is nearing completion, and I have to do falling weight defectometer (FWD) top of base and top of binder for designer validation. The design is HD 26/01 and uses figure 2.2, so the design is material choice and thickness. Not stiffness, so how does the designer validate his design? and how does he validate his design on a part built pavement that generally is still warm, but below 30 degrees C? It also occurred to my “catch up brain”, that the temp is recorded by drilling into the pavement to 100mm. I do not pretend to understand the analysis procedure, but if the binder course is 55mm thick and at around 30 degrees C and I drill into it and further into the base for 45mm and record a temp, analyse that I dare you. Surely the methodology is for the pavement (all the layers) to be at the same temperature, is it me? I have been beating a drum about FWD and gathering meaningless info at great expense, to tax payers, you and me, regarding this TS requirement.

So there is a change, a new requirement, in some tenders, appendix 1/5   we have to test top of base, top of binder, and now top of surface course. Well it seems my drum beating has backfired! Why is it not logical to look at the information gained, from top of base and top of binder and analyse it! Then take a step forward, perhaps the designers can’t analyse the data? Perhaps they should have thought of that before implementing a half baked notion of design validation? Would it not be sensible to have trial sections built and program to let the base cool, then test it, then spray bond coat, lay binder, let it cool and test that layer, followed by the surface course and again let it cool and test. This could be a modified 929 trial, and could be tested during the contract period to measure any ageing effect. Then when available during laying without interrupting the process, top of base and top of binder when cooled and not bond coated could be tested and subsequently all the surface course. There would be no need to run off with FWD data to analyse every section of work, from the trial and its back analysis the deflection figures of all sections tested would be there for comparison. Of course relying on the surface course data is too late if it is wrong, but on a design and build contract the risk is between the contractor, the designer and the blacktop supplier. Why is the client introducing this interrupting process of FWD during laying?

As i have blogged before the costs to interrupting the laying process to conduct FWD can be  more than the costs of  conducting the FWD, the people with the purse strings have not thought this out, why ? they don’t have to think.

And the purpose of this blog ? was to say yet again I am ensconced in the Marchback hotel, hence sleeping in England, the food is just sublime.

I have seen Guinea fowl running around in West Africa, but never tasted it. The Marchbank Hotel is about good food and game in particular and what does the menu provide? guinea fowl. Plus rabbit, pheasant, roe deer, halibut, lemon sole, esk salmon, venison burgers, leg of lamb cooked in the Aga for ten hours, if three of you like lamb and only eat breakfast you may manage this lamb feast. and guinea fowl ? subtle type of pheasant. Breakfast of kippers in cream is an omega start to the day, scrambled pheasant eggs with crispy bacon (pigs not fed on fish meal) with home grown fried tomatoes. Catch me on a diet! Shadow grows no less!

I’m in head office from a sojourn in the borders, nice place, like it, mostly owned by the Duke of Buccleugh of course. Reputedly the Duke if he ever did walk, could walk on his land from Edinburgh to Dumfries. Reminds me to locate my “who owns what” in Scotland book, think it is in Lochaline. In the Hotel. Speaking of hotels, if you are ever in the area of the A7 near the English / Scottish border, you must stay or at least eat in the Marchbank Hotel. Family run and just so nice, and good value too, best bit is the grub but you’ll have to visit to appreciate what I mean. You will have assumed, those naturally commercial, that I stayed in the Marchbank, first day i opened my curtains to Nuthatches on the bird table. Room 3, fantastic, when it’s your first live sighting and you’re a birder!! difficult to convey same excitement over breakfast to blooming staid civil engineers.

I digress, tender documents, well you never expect everything to be correct, that isn’t human. But I was examining a drawing recently that had a road plan on the drawing top and the longitudinal profile below with level data. Obviously one drawing part doesn’t share the same data, as the plan showed fill with false cuts to screen the road and the profile showed cut, fine but which was correct? Anyway it is design and build, or more correctly proscribe and build. Showing this drawing around returned “that’s nothing” look at this etc. The standard of  detail is appalling and the bulletin issues never help as it is just overload, then as you find apparent mistakes and dichotomies and TQ them, it jams up the system. Much time is spent not in producing solutions but trying to understand what the client requires. All this in a normal tendering environment, what if the Scottish Government advances some projects, to stimulate demand, to boost the economy!! I dread to think of the standard of detail, one thing will be correct, the legals, the caveats the whatever the circumstances we (the client) cannot be held responsible for anything, you (the bidder) must work your butt off to make sure you understand what we want from the junk issued.

But I am forgetting the golden rule: he who has the gold rules.  (from the wizard of ID) is that still extant?