Tuesday 14 May 2019


by Dave Roberts

In May 2019 'Harry Random' (a pseudonym) emailed The Middlewich Diary suggesting a 'Middlewich Riddle' which might intrigue people and generate a lot of interest. And it most certainly did...

Here's 'Harry's' original message:

This would make a fantastic (and completely non controversial) question for the Middlewich Diary, and I can promise you the answer will generate a huge amount of local interest.

Six inches can make a lot of difference, but it seems that since 1971 something in Middlewich seems to have officially reduced in size without some visitors and many residents even noticing.

Can you guess what the answer is?


'Harry' also provided a clue to the riddle:

'It's very important, very topical and everyone in Middlewich has seen it and knows what it is.'

I hadn't a clue, save for the fact that 'Harry's' mention of 'visitors' made me think that there might be a canal connection.

So we put the conundrum to the people of Middlewich via the Middlewich Diary and, as 'Harry' prophesied, created an awful lot of interest.

Here's the answer:

'Harry' writes:
I can't remember where online I found the black and white photograph below, but it was described as having been taken in 1971. The bit that I caught my eye was the height of the aqueduct is shown as 12'.0", yet the photograph that was taken in 2011 shows the height as 11' 6".

So what has happened to the missing six inches? - Has the bridge sunk, the road surface risen, was the old height measurement just an estimate, or is there another explanation?

The Aqueduct in 1971 - Max. Headroom 12 feet.

The Aqueduct in 2011 - Max. Headroom 11ft 6 ins.
So what happened to the missing six inches? Surely the road cannot have been re-surfaced so many times in forty years that it's risen six inches? And surely the aqueduct, besieged and battered though it may be by errant truck drivers, can't have sunk six inches? Or, as 'Harry' also suggested, was the height of the aqueduct measured incorrectly at some point, and the figure corrected in 2011?
'Harry' of course, never stints on research, and copied his original email tp Paul Cassell, who's a retired transport manager and consultant.

Paul offers us an expert view of just why that vital six inches 'disappeared'. While he's at it Paul also gives us his considered view of just what is causing the current problems with HGVs striking our poor, beleaguered aqueduct:

Dear Harry,

Thank you for the enquiry from yourself and Dave Roberts, I think I have the answer for you both. Nothing as dramatic as the aqueduct sinking or the road surface rising sadly, just a legacy of Britain joining the European Economic Community as it was known back in the 70’s!
As part of EEC road transport harmonisation in the early 80’s we were allowed to increase vehicle gross weights in line with those of most European countries, the most notable being the increase from 32.5 tons to 38 tonnes for maximum weight articulated vehicles with five axles. To ensure safety on the UK roads every road bridge was re-assessed for both weight carrying capability and appropriate signage for weaker bridges. As a ‘belt and braces’ approach weights were actually assessed for up to 44 tonnes+ as this was always on the horizon and is of course today’s maximum weight threshold.
Bridge heights also came in for scrutiny as many had either never been properly marked or hadn’t been checked since resurfacing may have reduced the height clearance or just not very accurately measured in the first place! The EEC regulations demanded clearance heights be marked in metric to one decimal place for visiting European drivers who only understood metric measurements and who had metric height warning signs in their cabs. We insisted that our old feet and inches measurements also remained as vehicle travelling height signs in feet and inches were a legal requirement inside cabs for driver information in the UK. Hence why all UK bridges now have both a metric and imperial sign either on the bridge or on the approach to it.
Arch bridges are also marked with ‘goalpost’ signs whereby the stated height is at the upper corners of the goalpost although the centre line through the arch will of course be a little higher, as is the case with Nantwich Road bridge. This is obviously to accommodate square bodied trucks although I know of one vehicle operator who could creep under the canal aqueduct with a milk tanker as long as he kept to the middle of the road!
The checking and re-signage exercise involved an element of calculation ‘rounding down’ which knocked a few inches off the exact conversion calculation particularly at high risk bridges. Originally at 12 ft the Nantwich Road bridge would have been 3.6m, but presumably on checking the height and observing the score lines in the brickwork, a decision was probably taken to round down to 3.5m which is 11 ft 6 inches.
Once all bridges had been assessed for load bearing and height clearance, computerised routing systems, truck-specific satellite navigation systems and good old trucker’s atlases provided by the Freight Transport Association and Road Haulage Association to their members were updated to (hopefully) prevent bridge strikes and collapses!
The problems now experienced at the Nantwich Road aqueduct, in my opinion, are because truck drivers are relying on ‘car’ sat nav systems, not helped by the fact that some mapping software used shows the road going over the canal at that point!!
Well you did ask……………………!!!!!!!!


Many thanks to Paul for taking the trouble to give us this highly professional reply to 'Harry's' question, and to 'Harry' for posing the riddle in the first place.

Congratulations to everyone who got the answer right, and especially to RUTH DUCK who seemingly came up with the answer within minutes of  the riddle being posted.

Thanks to the many people who 'had a go'. There were hundreds of highly original and ingenious answers, and quite a few people were 'on the right track' right from the beginning, even if they didn't quite get there!

Dave Roberts

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