However, because the display of imperial units continues to be required on road signs, the manual inevitably exhibits a certain amount of awkwardness when it comes to specifying the siting of road signs showing distances – adding complications to the work of road contractors that would be unnecessary if metric signage was used.

Sometimes “yards” are allowed to mean metres (as is the case for road works), in other cases distances are specified in yards (leaving the conversion to the contractor), and sometimes metric distances are specified for corresponding nominal imperial distances.

e.g. page 20 of Traffic Signs Manual Chapter 4 has a table specifying the siting of approach signs indicating a reduction in the number of lanes.

distance legend
135 m 150 yds
180 m 200 yds
270 m 300 yds
360 m 400 yds
800 m 1/2 mile

http://www.dft.gov.uk/pgr/roads/tss/tsmanual/trafficsignsmanualchapter4wa4182

Generally, a variation of up to 10% is permitted between the actual distance and the distance shown on the sign. So showing a distance of 200 m as “200 yds” would fall within this tolerance.

http://www.dft.gov.uk/pgr/roads/tss/trafficsigns.pdf

Mentions the trams’ km/h speed limit signs

Here is one where conversions are made:

http://www.dft.gov.uk/pgr/roads/tss/tsmanual/trafficsignsmanualchapter4wa4182

See page 21 for examples.

You may be interested in how heights are signed-up

(See pages around 31).

There seems to be a mix - and a mix between DfT documents.

Is the rest of the manual similar to this? If so, metric distances are “wired in” throughout. In that case, all distance signs should be metric with Imperial overlays awaiting the eventual M-Day.

See Traffic Signs Manual Chapter 8

http://www.dft.gov.uk/pgr/roads/tss/tsmanual/chapter8/trafficsignsmanualchap8ro4180

e.g. page 74 states:

“The principles for the approach signing are: …
a “road works” sign with supplementary plate “800 yds” placed on the near side 800m in advance of the works lead taper;
a “road works” sign with supplementary plate “400 yds” placed on the near side 400m in advance of the works lead taper; and
a “road narrows” sign with supplementary plate “200 yds” placed on the near side 200m in advance of the works lead taper.”

“If you ask the DfT (via your MP) why we don’t go metric on the roads, the answer used to be that >50% of drivers were educated before metrication, and so not changing would affect fewer people. Now that’s no longer true, they’ve changed their excuse and say that it would be too expensive.”

To know for sure how much it would really cost, all one needs to do is look at the cost the other nations endured when they metricated. most were able to come up with unique plans that actually reduced the costs and were able to make it fairly cheap.

The excuse about >50% of drivers were educated before metrication is really saying that British citizens are ignorant and can’t learn anything new. How do they justify the fact that the other countries that metricated also had a population not educated in metric, and yet the people adapted with zero consequences?

The only real reason to keep the signs in miles and yards is because it gives the imperialists hope that imperial is not only dead yet, but there is a chance, albeit slim, for an imperial revival. Road signs in miles are a visible sign that imperial is still alive and kicking in the UK.

Another point of interest is how many of the road signs are correct to their imperial designations? How many road signs are placed at rounded metric distances with the miles being an approximation of that distance? How many signs stating a distance in yards is really that distance in metres? Eg. How many 200 yard signs really are at a 200 m distance? Who would really know they are right or wrong?

UKMA should push for a moratorium on putting up new speed limit signs until after the switch. The government would of course resist this as they are still trying to clamp down on speeding by creating more speed limits; and this would create an opportunity for public debate.