This week, Ronnie Cohen looks at a problem faced by the UK Department of Transport (DfT) resulting from the our two-system measurement muddle. With continuing staffing cuts in Civil Service and the diversion of effort to deal with Brexit, it would appear that such problems are unlikely to be resolved in the foreseeable future.
The Traffic Signs Regulations and General Directions 2016 (TSRGD) were made on 16 March 2016, laid before Parliament on 22 March 2016 and came info force on 22 April 2016. Since TSRGD 2016 came into force, there have been updates to the online versions of the Know Your Traffic Signs publication and the Traffic Signs Manual (TSM). Know Your Traffic Signs was last updated on 4 May 2016 and the TSM was last updated on 23 February 2017. As the TSRGD 2016 was already in force when the most recent updates were made to these publications, it would be reasonable to expect them to reflect the current regulations regarding the mandatory use of metric units on all new the replaced vehicle dimension signs. However, this is not the case.
All references to vehicle dimension signs in the TSRGD 2016 make it clear that the metric units are now mandatory. Imperial-only versions of the new and replacement signs are no longer authorised, though existing imperial-only vehicle dimension signs can remain in place until they become life-expired or are due for replacement. Here is a summary of all the references to vehicle dimension signs that I have found in the TSRGD 2016:
- Sign table — Schedule 2, Part 4, Item 2 on page 55 shows Diagram 530A. It shows a dual triangular height limit sign.
- Sign table — Schedule 2, Part 4, Item 3 on page 56 shows Diagram 531.1A. It shows the maximum headroom available at arch bridge ahead with two triangular signs with images of arched bridges (one imperial and one metric).
- Sign table — Schedule 2, Part 4, Item 5 on page 57 shows Diagram 629.2A. It shows a dual circular height limit sign.
- Sign table — Schedule 3, Part 2, Item 25 on page 73 shows Diagram 629.1. It states that vehicles or combinations of vehicles exceeding the length indicated are prohibited. It shows two circular length limit signs together side-by-side (one metric and one imperial).
- Sign table — Schedule 3, Part 2, Item 26 on page 73 shows Diagram 629A. It shows a dual circular width limit sign.
- Sign table — Schedule 3, Part 2, Item 27 on page 73 shows Diagram 629.2A. It shows a dual circular height limit sign.
- Sign table — Schedule 12, Part 20, Item 6 on page 327 shows a dual triangular height limit sign.
- Sign table — Schedule 12, Part 20, Item 33 on page 331 shows two circular length limit signs together (one metric and one imperial).
- Sign table — Schedule 12, Part 20, Item 34 on page 331 shows a dual circular width limit sign.
- Sign table — Schedule 12, Part 20, Item 35 on page 332 shows a dual circular height limit sign.
- Sign table — Schedule 12, Part 28, Item 23 on page 363 shows Diagram 818.5. This is described as the location of a low bridge with indication of alternative route. It contains an inset image of a dual triangular height limit sign.
- Sign table — Schedule 13, Part 6, Item 14 on page 386 shows Diagram 7243. This is described as a temporary road layout with lane restrictions. It contains an inset image of a dual circular width limit sign.
The Know Your Traffic Signs online manual still shows imperial-only vehicle dimension signs in a number of places. Drivers would still be expected to be familiar with the imperial-only versions because many still exists on the road network and it will take a few years for them all to be phased out and replaced with the dual-unit versions. The print and online versions of Know Your Traffic Signs will eventually need to be updated when imperial-only vehicle dimension signs no longer exist. However, the Signs for road works and temporary situations section on pages 130-132 should not show imperial-only width restriction roundels on road works signs. These signs are temporary and road contractors are no longer authorised to use the imperial-only width limit roundels on road works signs. The TSRGD 2016 states that they must use the dual-unit versions of these roundels on road works signs.
As the TSM instructs road contractors on signage, it is important that the TSM reflects the current regulations in the TSRGD 2016. In several places, it does not. The TSM contains several references to imperial-only vehicle dimension signs, which are not authorised in TSRGD 2016. Accompanying text suggests that the metric units are optional and does not make clear that dual-unit circular and triangular width and height limit signs must be used. Likewise, it does not make clear that metric length limit signs must be shown alongside imperial length limit signs but suggests that the metric versions of these signs are optional. These discrepancies can be found on the following pages (using PDF page numbering, which counts the cover page as Page 1):
- Pages 40-42 of TSM Chapter 3.
- Page 34 of TSM Chapter 4.
- Pages 40-41, 64, 71, 80, 121, 131, 152 and 154 of TSM Chapter 7.
- Pages 99-100, 186, 188, 198, 206 and 214 of TSM Chapter 8 Part 1.
Ideally, the text around the images in Know Your Traffic Signs and TSM should also be updated to reflect the current regulations in TSRGD 2016 which mandate the use of dual units on new and replaced vehicle dimension signs. Presumably, lack of staff prevents this being done immediately for the online versions of these publications. Any forthcoming print versions of these publications should be updated to reflect the current regulations, but whether this happens remains to be seen.
This lack of co-ordination between the TSRGD 2016, TSM and Know Your Traffic Signs publications is an unfortunate consequence of the decision taken in 1972 not to proceed with the conversion to metric measures of UK road traffic signs, and it does the UK Government no credit. Perhaps it is an indication that our two-system measurement muddle has become a luxury the UK can no longer afford.