Ronnie Cohen writes about the muddle of measurement units he has found on public signs in London, particularly those related to public transport and cycling. If two measurement systems were not bad enough, he has found there are now three.

For public signs in London, we have metres on maps in London Underground and Overground trains, metres on public notices at stations, yards on public signs at stations, metres and yards on private sector signs and advertisements, minutes on signs and maps for pedestrians and cyclists, yards and fractions of a mile for drivers, metric-only private sector restriction signs and imperial-only and dual restriction signs on our roads. Not only do we face inconsistency in the units used, we also face the problem that the distances given in different units are often different, sometimes significantly.

Here are signs that show the inconsistent use of units in different places on public transport in London:

The top-left sign shows the distances to local places at the exit to Barbican tube station in minutes. The top-right sign shows the distances to local places at Euston train station in yards. The bottom-left sign shows the distance to Kilburn Park station on a public notice at Kilburn High Road overground station in metres. The bottom-right sign appears on tube maps on Jubilee Line trains and shows the distances to nearby DLR stations in metres. So we have a mixture of yards, metres and minutes used to express distances on public transport in London. Why are millions of passengers in London denied consistent information about distances on public signs and maps? The use of common units would support consistency whereas the use of different units undermines that. The current situation makes it hard to compare distances. How can we compare distances in minutes with distances expressed in yards and metres?

This confusing muddle even extends to the provision of information to the public. On the Transport for London (TfL) website, the web page about the Tube Upgrade Plan uses a mixture of kilometres and miles to express distances (see http://www.tfl.gov.uk/corporate/projectsandschemes/18072.aspx#qu7). This web page contains a Common Questions section. In part of the answer provided to one of the questions, “When will the work be finished?”, TfL writes, “We’ve replaced over 200 km of track.”. However, in part of the answer provided to another question, “Why don’t other metro systems have these issues?”, TfL writes, “We have 249 miles of track compared to 133 miles in Paris or 56 miles in Singapore.” Now ask yourself, how much of the total tracks have been replaced? You cannot answer this question without doing some mental arithmetic to convert miles to kilometres or kilometres to miles. If TfL had written, “We have 400 km of track compared to 214 km in Paris or 90 km in Singapore”, we would have easily been able to see that half of all the tracks have been replaced, a fact obscured by the inconsistent use of measurement units.

Given that Imperial measures are permitted only for “road traffic signs, distance and speed”, that the use of miles is mainly confined to the UK and USA, and that kilometres are used worldwide, TfL could improve communications with the public, including the millions of foreign residents and tourists who come here from all over the world, by using metric units exclusively in its communications with the public. Metric units also have the added advantage of being clear and unambiguous, hence the use of metric units to define all old and new measurements.

Here are signs that show the inconsistent distances as well as inconsistent units in different places on public transport in London:

The images in the first column appear on tube maps on underground trains. The images in the second column are public signs that appear at train stations.

The top row of images shows a distance of 200 metres from West Hampstead underground station to West Hampstead Thameslink station. However, when you go to the West Hampstead Thameslink station, the sign shows a distance of 200 yards from there to West Hampstead underground station. So what is the distance between the West Hampstead Thameslink station and West Hampstead underground station? Is it 200 yards or 200 metres? They cannot both be right. One of the figures must be wrong. Which is correct? There seems to be confusion over the difference between yards and metres.

The second row of images shows a distance of 400 metres from Euston Square underground station to Euston train station. However, when you go to Euston train station, the sign shows a distance of 510 yards (466 metres) from there to Euston Square underground station. There is a big difference between these figures. It exposes the folly of using two systems of measurement for showing distances between stations. Despite the information given, we still do not know the correct distance between Euston train station and Euston Square underground station. It is obvious that one of the figures is wrong. Again, we ought to ask, which is correct?

This is a typical example of the lack of consistency in the use of measurement on our roads and on public transport. Not only do we face a lack of consistency in the use of metric and imperial units, we also face a lack of consistency in the distances shown between stations.

The third row of images shows a distance of 100 metres from Clapham North underground station to Clapham High Street train station. Interestingly, no distance is given to Clapham North underground station from the sign at Clapham High Street train station, despite the fact that this sign gives distances to other locations in the local area. I wonder why.

The strangest image shows two signs next to each other outside Baker Street underground station, one showing a distance of 100 metres to Madame Tussauds tourist attraction and the other showing a distance of 370 yards (338 metres) to the same place.

There are other examples of muddled distance measurements in London. For example, maps inside Westfield White City shopping mall use a metric-only scale. Yet the bus station outside the shopping mall contains a public sign with a map that shows distances expressed in minutes.

For cyclists, this situation is particularly bad as they have to tolerate signs like the ones shown here:

The image on the left shows the number of minutes to particular locations. I wonder how fast you need to cycle to arrive at these places in the specified number of minutes. The signs give you no clue. It could take more or less time to get there than the number of minutes shown depending on how fast you cycle. The difference could be huge. That is why the display of minutes on cycling signs is daft. The DfT prefer to show cycling times rather than allow metres on distance signs. And of course, such information is of even less value to other road users.

Given the introduction of minutes on cycling signs and the requirement use of miles for distances on UK roads, I wonder whether the cycling sign on the right, which contains no unit names, abbreviations or symbols, shows the number of minutes or the number of miles to the places shown on the sign. This is unclear. Are cycling signs only supposed to show minutes or can they show miles like other UK road signs? And if minutes, why not metres?

The measurement mess is not just confined to road transport. It is bad enough that British drivers have to use imperial signs that are incompatible with driver location signs and emergency marker posts, the Highway Code, the Ordnance Survey and with road signs in all other European countries. This muddle affects all transport signs, including signs for pedestrians. The units used are inconsistent and often confusing and the distances are often contradictory. Where there are significant differences, the public are left puzzled wondering which signs to believe. London’s millions of passengers, pedestrians and road users deserve better than this. It is about time that our leaders woke up to the fact that we only need metres and kilometres to express distances for all forms of transport.

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