Whilst engaged on amending illegal signs in kilometres and metres in the Newham area of London, ARM supporters came across a grey car park height barrier outside a company off Abbey Lane, London E15.

The inscription on the grey bar said: 1.65m - 6'6".

Whereupon ARM supporters checked the height and found it to be exactly 6' 6" - and immediately painted over the seriously incorrect metric height which could have been dangerous (well, for the 'metric-educated' amongst us, anyway).

A company employee came out to find out what was going on, and was informed that the metric height was completely inaccurate and did not comply with regulations.

The ARM supporters were thanked for their aasistance

<<ARM supporters checked the height and found it to be exactly 6' 6">>

The sign still reads 6'6".

So, what happens if my car is also exactly 6'6" - Will ARM pay for the damage to my car when I scrape the roof?

ARM claim that the traffic sign must comply with the TSRGD, and use this as justification for their vandalism.

Guidance on height marking

"The figure on the sign to indicate the available headroom should be at least 3 inches less than the measured height to allow a safety margin and should be expressed to the nearest multiple of 3 inches. The height of the sign therefore shows the safe height for a vehicle passing under the bridge."

Assuming ARM's measurements are accurate, the sign should therefore read (at most) 6'3".

If the height of the obstruction is actually less than 6'6" at any point, I would contend that the sign should read 6'0" (at least 3 inches clearance and rounded down)

I would agree that the quoted metric measurement is hopelessly wrong, but at least anyone following the advice it used to give wouldn't have scraped the roof of their vehicle. Now the sign is imperial only, the danger of damage to a vehicle has actually increased!

The only cost that a driver of a vehicle over 1.65m would have faced would have been the extra time & cost of finding an alternative parking place.

Tony said "the seriously incorrect metric height which could have been dangerous"

Am I missing something? How could this lower height possibly be dangerous?

To sum up, this is yet another example of ARM's two faced attitude!

Unlawful/incorrect & dangerous imperial = OK

Unlawful/incorrect (yet safe) metric = must be eliminated

6 feet 6 inches is hidden metric for 2.0 m exactly. If the sign reported the barrier height at 1.65 m then there was no possibility that the barrier could be erroneously hit. The 1.65 m height restriction notification gives a margin of error of 350 mm. Now it is possible for someone to hit the bar if they have something exceeding the covered limit.

I think 350 mm is a bit much. 35 mm would probably be enough.

Thanks Tony for giving a good example of how using two measurement systems can lead to errors.

And also for confirming what we knew already - that safety is not a concern of ARM as long as you can see your beloved imperial measurements

re (Beranger quoting from the Traffic Signs Regulations?):

Guidance on height marking

"The figure on the sign to indicate the available headroom should be at least 3 inches less than the measured height to allow a safety margin and should be expressed to the nearest multiple of 3 inches. The height of the sign therefore shows the safe height for a vehicle passing under the bridge."

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REPLY: I was not aware of that. Is it in the 2002 TSRGD? It would certainly explain why - until metrication started creeping in, all height signs were in units of 3" - 14' 0", 14' 3", 14' 6", 14' 9" etc.

Do the regulations actually specify '3 inches'?

That seems curious in a document littered with references to lettering and sign size all being in millimetres.

Incidentally the regulations also specify that metric alternative (i.e. optional) heights and widths shall be only to the nearest tenth of a metre.

There are quite a few examples of rogue, unlawful, signs giving metric heights to two decimal places i.e. to the nearest centimetre.

I saw one on the M25 the other day, a lane width of '2.75 metres'. And with no Imperial alternative given.

Unauthorised. On two counts.

How come the metric measurement hadn't been recognised as wildly wrong?
If the imperial was wildly out then would more people have noted how absurd it looked?

re: "How come the metric measurement hadn't been recognised as wildly wrong? If the imperial was wildly out then would more people have noted how absurd it looked?"

CLUE: In a recent independent survey, 98% of people said they understood Imperial dimensions and only 29% said they understood metric dimensions. In a recent survey by ARM, 100% of personal ads, where those who placed an ad gave their height - or the height of those they were seeking - in feet and inches, with 0% giving their heights in metric

<<How come the metric measurement hadn't been recognised as wildly wrong?
If the imperial was wildly out then would more people have noted how absurd it looked?>>

In the US, a lot of personal pickups, SUVs, and vans would be over 1.65 m, but are they very common in the UK? People driving a car, vs a light truck, wouldn't care. Since I'm 194 cm, I'd be more concerned about duck-waddling to the exit after I parked.

Even if someone noticed, what percentage would go to the trouble of arguing with the parking attendent or tracking down the owner and sending a letter (besides Tony).

Tony - If what you are saying is correct, that means the metric notation is being completely ignored. There again - a sign like this points to that observation being correct.

John - Unfortuntaely we have SUV's and the like here. Worse, we have people carriers too. Before long we'll all be driving double decker buses. After all, there's a plentiful supply of cheap petrol around, isn't there - which means we can all go around doing 300 L/100km or 1.3 mpg

I know you have them in the UK, but they aren't half the personal vehicle fleet as in the US, are they?

(Those must be really big gallons -- check your conversion)
While I was a sail-boater, I know power-boaters who would be pleased with that fuel economy.

Do you have people carriers as a "choice for ordinary people"?

I still can't work out why someone would want to drive a psuedo-mini-coach to pop down the shops!

<<Do you have people carriers as a "choice for ordinary people"?>>

I'm not sure how you would define "people carrier." Minivans may hold 5-8 people in 2-3 rows of seating. Full size vans may hold 6-15 people in 3-4 rows of seating, and varying degrees of luxury. Large numbers are individually owned.

Car rental companies may use mini-buses at airports holding 20-30 people, but I've rarely seen individuals using those. However, motor homes, RVs certainly approach the size of city buses, and are't going to fit in a parking structure. A lot of people use those for vacations; they usually don't seat many as they providing for sleeping, cooking, personal hygiene.

Tony asked
"re (Beranger quoting from the Traffic Signs Regulations?)"

No Tony. I was quoting from guidance to the TSRGD 1994. I believe that this guidance is still in force - unless, of course, you can point me toward any new method of calculating the maximum safe vehicle height.

"ANNEX E
to Circular Roads 4/94

Calculation of signed height

4. The figure shown on the signs to indicate the available headroom should be at least 3 inches less than the measured height to allow a safety margin, and should be expressed to the nearest multiple of 3 inches. Thus the maximum figure which should normally appear on a sign is 16' 0".

Traffic authorities should remeasure the headroom after re-surfacing the road or carrying out other similar works, and must change the signs if road works alter the clearance beyond the 3 inches limit."

"5. When it is intended to indicate the safe clearance height in metric units as well as imperial ones, it is not acceptable simply to convert the imperial measurement to its metric equivalent.

The bridge clearance height must be measured with a metric rule to two decimal places, rounding down to the nearest centimetre, and the following formula adopted for calculating the appropriate signed height:

(i) If the second decimal number is 8 or 9, delete it and sign the bridge with the remaining whole number and the first decimal number.
Eg: Actual measured height: 3.29m
Delete second decimal number
Signed height: 3.2m

(ii) If the second decimal number is 7 or less, delete it and reduce the first decimal number by 1. Sign the bridge with the remaining whole number and first decimal number, as reduced.
Eg: Actual measured height: 3.45m
Delete second decimal number: 3.4m
Reduce by 0.1m
Signed height: 3.3m"

The imperial formula will provide a tolerance of between 3 & 6 inches, the metric a tolerance of between 8 & 18 centimetres

Tony said

"I was not aware of that. Is it in the 2002 TSRGD? It would certainly explain why - until metrication started creeping in, all height signs were in units of 3" - 14' 0", 14' 3", 14' 6", 14' 9" etc.

What an admission from Tony! He has previously claimed that ARM promote road safety, yet he believed that bridges should be marked with their actual height!

Imagine the scenario - ARM find a carpark with a marked height restriction (on the grey bar) of 1.7 metres. No imperial equivalent is marked. They vandalise/obliterate/eliminate the marked height & get out their trusty yardstick. The bar is over 6'2" from the ground. They check the conversion & have a good laugh about the inaccurate metric measurement......

"It's nearly 18cm out" chortles one member "This is going to look great in the press release! How about something like 'ARM removed a metric measurement which was wrong by over 10%. It was replaced with a nice rounded user-friendly 6'3". A major improvement in road safety' What a result!"

Meanwhile, a man goes into the car showroom next door and says "I need a car with plenty of headroom........"

Danny said

"6 feet 6 inches is hidden metric for 2.0 m exactly. If the sign reported the barrier height at 1.65 m then there was no possibility that the barrier could be erroneously hit. The 1.65 m height restriction notification gives a margin of error of 350 mm. Now it is possible for someone to hit the bar if they have something exceeding the covered limit."

Danny, do you really believe that everything is "hidden metric"?

Bud said

"I think 350 mm is a bit much. 35 mm would probably be enough."

Agreed re the 350mm, but consider how much the back of the vehicle will rise if the driver has to brake sharply when the rear of his vehicle is under the lowest point. It would be touch & go whether 35mm would be enough.

Andy said

"And also for confirming what we knew already - that safety is not a concern of ARM as long as you can see your beloved imperial measurements"

Well said! Note that Tony failed to address any of my "safety" points.

Kilobee said

"How come the metric measurement hadn't been recognised as wildly wrong?
If the imperial was wildly out then would more people have noted how absurd it looked?"

Many truckers suspect that imperial bridge heights are deliberately understated (maybe that's why bridges are hit!) I'll try to find some figures to back this up.

Remember also that this sign was at the entrance to a carpark. If it was a multi-storey, the lowest points are often on the ramps - not at the entrance.

Kilobee also said

"Do you have people carriers as a "choice for ordinary people"?

I still can't work out why someone would want to drive a psuedo-mini-coach to pop down the shops!"

I'll bet you don't have kids! 6/7 seaters are very practical for large families, but may not fit into very low carparks (Fiat Multipla, Renault Espace etc)

<<I'll bet you don't have kids! 6/7 seaters are very practical for large families, but may not fit into very low carparks (Fiat Multipla, Renault Espace etc)>>

Thanks for a model reference.

Now I can answer kilo-bee. Yes we have people carriers in the US. That segment (6/7/8 seaters) in three rows is a "mini-van" here. Very popular family vehicle here; the stereotypical "soccer mom" vehicle. A midsize SUV would have similar room and offers optional 3rd row seating for the same capacity.

"the stereotypical "soccer mom" vehicle"

I'm glad you mentioned that - its something I've always wanted to ask.

What the heck is a "Soccer Mom" (or, I guess "Football Mum" in England)

re (Beranger): "Imagine the scenario - ARM find a car park with a marked height restriction (on the grey bar) of 1.7 metres. No imperial equivalent is marked. They vandalise/obliterate/eliminate the marked height & get out their trusty yardstick. The bar is over 6' 2" from the ground. They check the conversion & have a good laugh about the inaccurate metric measurement...

"It's nearly 18cm out", chortles one member. "This is going to look great in the press release! How about something like 'ARM removed a metric measurement which was wrong by over 10%. It was replaced with a nice rounded user-friendly 6'3". A major improvement in road safety' What a result!"


REPLY: Thanks! We'll use this as a template for our next press release. There's no charge, is there?

Well, specifically a suburban mom driving kids (and any needed equipment) to soccer practice or games. More generally, a mom driving her kids around to any number of activities, to and from school, etc.

Well. There we have it.

ARM admit that they wish to mark areas where height is restricted with the actual height of the roof rather than the safe maximum vehicle height that may be taken into the area.

Just in case anyone doesn't understand exactly what I mean:-

1) In the ficticious scenario I set out above, the actual roof height was 1.8799m. Using the formula set out in Annex E to Circular Roads 4/94, this rounds firstly to 1.87m & secondly to a maximum safe height of 1.7m (the original marking)
2) The actual roof height in imperial is a tiny fraction over 6'2" (74.01 inches). If ARM had used the imperial formula set out in Annex E to Circular Roads 4/94, the maximum safe height to mark would be 5'9".
3) By adopting the "press release", Tony appears to agree that ARM would mark 6'3" (in exactly the same way that they left 6'6" displayed in Abbey Lane E15)
4) This means that any vehicle over 5'9" is at risk (according to the Annex E imperial formula) and that any vehicle over 74.1 inches is certain to hit the roof.

Tony, please use the template with my best wishes. May I suggest that you add "Relying on ARM's measurements may result in serious damage to your vehicle"

May I also suggest that you cease all claims to improve road safety - you obviously condone signage that misleads drivers as to the actual safe maximum height of vehicle that may enter the carpark.

<<<Well, specifically a suburban mom driving kids (and any needed equipment) to soccer practice or games. More generally, a mom driving her kids around to any number of activities, to and from school, etc. >>>

But why soccer? Is it because soccer (I hate that word. Its called football) is seen as a bit of a middle class thing in the US?

<<But why soccer? Is it because soccer (I hate that word. Its called football) is seen as a bit of a middle class thing in the US?>>

Sorry, it can't be "football" here because (American) football is football. I doubt it could even be "futbol" due to possible confusion.

Although pro soccer doesn't get much support here, it is a popular high school sport. If anything, I would say it is more an "upper middle class" or "wealthy" thing. Typical inner city schools are more likely to have good basketball and football teams, with kids hoping to turn pro as a way out of the "ghetto."

Soccer, tennis, golf, lacrosse, hockey, etc tend to be more suburban and more for love of the sport, although they have (in varying degrees) pro followings and kids' aspirations of turning pro.

If anything the term is derogatory towards the mom, as it is very diffciult to be both a soccer mom and working mom, not the sport. It tends to imply a stay-at-home mom, or one who only works part-time, and that carries some implications the family does OK on Daddy's salary. At least, that is my take on it.

Cheers for that! Had often wondered where that saying came from.

re (Beranger): "Tony, please use the template with my best wishes. May I suggest that you add Tony, please use the template with my best wishes. May I suggest that you add 'Relying on ARM's measurements may result in serious damage to your vehicle'"


REPLY: LOL! Remember the case of Adam Doggett? - you know, the one whose jeep got stuck under a low road bridge because Broxbourne Borough Council had erected an illegal height sign in metres only, saying 1.4m? And the other case of the company which wrongly (and unnecessarily, as it turns out) converted an imperial height sign into metric at about 9" above the correct height so that a lorry crashed into a canopy, causing thousands of pounds worth of damage?

If you don't object, I've ever so slightly amended your template; it now reads:

"UKMA's plan to compulsorily obliterate 1.5 million perfectly serviceable Imperial road signs in the U.K. and replace them with metric distances and speeds may result in serious damage to your net pay*"


* P.S. Roughly a billion quid

<<REPLY: LOL! Remember the case of Adam Doggett? - you know, the one whose jeep got stuck under a low road bridge because Broxbourne Borough Council had erected an illegal height sign in metres only, saying 1.4m?>>

It is amazing to me how well Canadians do with SI speeds, distances, heights, when I hear of the difficulties Brits have learning metric. They must be freaking geniuses in Canada. Oh, wait, . . . even the Americans don't do that badly when they visit Canada.

I think honestly only those who are complete idiots or philosophically adamantly opposed to metric (or both??) have any real problems. I don't have any first hand experience with Australians or South Africans, but rumor has it that they learned metric OK too. Apparently even the Irish.

re (JohnS-MI): "when I hear of the difficulties Brits have learning metric..."

REPLY: Usually you make very good points but you've missed by a mile on this one.

There are two contributory and interrelated reasons why even metric-educated people like Adam Doggett don't undestand a sign stating '1.4m'.

First, there is a stubborn resistance to throwing away our tried and tested measurement system. A bit like we hang on to our King and Queen. Something to do with tradition and our being a nation (England) continuously since about 860 AD (Scotland and Wales joined in much later but also have long-established national traditions).

Second, and this is really partly becaues of the first - the government has hesitated about 'completing' the elimination of Imperial weights and measures.

You see, we live and let live as a people - but then we don't like to be pushed around and told what to do, either.

In this respect I speak for many of us

I agree it is unwillingness not inability. I still question why. I chose most of my examples to at least be Commonwealth nations, who consider the Queen to be Head of State, at least formally, although having no real power.

In part, your government is hesitant because of the resistance of groups like ARM. But you have completed so much more of the task of metrication than we have, I don't see why you don't complete the last bit, or at least make metric legal, side-by-side with Imperial, in those remaining areas. The part that most mystifies me is that your "preferred measurement system" (SI) is illegal or unlawful for certain things but mandatory for most things. I can't quite get my head around that.

<<
In part, your government is hesitant because of the resistance of groups like ARM.
>>

I think the government is hesitant because they have realised that there are many more important things to spend taxpayer money on.

<<
In part, your government is hesitant because of the resistance of groups like ARM.
>>

I think the government is hesitant because they have realised that there are many more important things to spend taxpayer money on.

thanks for the info on "soccer mom" - that sorts one of life's millions of questions out!