Blue Roundels

Synopsis

Blue roundels were originally used only to give mandatory instructions. Those with a single large arrow still do. But now, they have been joined by blue roundels which show types of vehicle, e.g. a bus or a cycle, or the word "taxi". These have a different meaning: they indicate that the white vehicles are permitted to pass the sign, but other types of vehicle are prohibited. The section of road beyond the sign is for the exclusive use of the types of vehicle shown. 

Many motorists incur fines for going through "bus gates" because they do not realise until too late that they are prohibited. Prohibitions are normally indicated by circular signs with a red border. Signal red is the colour of prohibitions. It is suggested that the blue roundel signs used at bus gates should be mounted on signal red backing boards. The effect can be seen in the pair of images below:

Worboys

Blue roundels are circular signs with white graphics on a blue background. They have been part of our traffic signs since the implementation in 1964 of the Worboys Report. That report proposed a coherent structure for traffic signs, based largely on the 1949 UN Protocol on Road Signs and Signals. As the report explained:

46. The Protocol requires that signs should be of three basic shapes — triangular for warning signs, circular for those giving definite instructions and rectangular for informatory signs. It further requires that: —

(a) warning and prohibitory signs (with one or two exceptions) should have a red border with a white or light yellow ground and black or dark symbols ;

(b) mandatory signs should have white symbols on a blue background ;

(c) directional signs should be in light lettering on a dark background, or vice versa; and

(d) other informatory signs should have white legends on a blue background or, in certain cases, black symbols on a white rectangular background within a blue surround.

The structure which Worboys proposed was:

A. Signs Giving Definite Instructions

(a) Mandatory Signs

51. In general the mandatory signs recommended have a white symbol on a blue circular background. But there are two deliberate exceptions; the Stop and Give way signs have distinct shapes and colours and capital letters in order to produce a more immediate impact.

(b) Prohibitory Signs

63. With the exception of the No entry sign and waiting restriction signs all prohibitory signs are distinguished by a red circle with a white centre which usually carries a black symbol. Waiting restriction and limited parking signs are dealt with in paragraphs 83 to 87.

(c) Waiting restriction and limited parking signs

B. Warning Signs

88. Warning signs are distinguished by a red triangle containing a black symbol on a white ground.

C. Informatory Signs

130. Protocol informatory signs are basically rectangular. 

D.Temporary Signs

Worboys applied this structure consistently. This led to some signs which look odd today, e.g.:

We are used to seeing this sign as a roundel on bollards which traffic can pass on either side. Worboys observed, correctly, that this is an informatory sign, not a sign giving a mandatory instruction. The Committee therefore made it rectangular. We may infer that the costs of requiring two types of bollard, one for circular signs and the other for rectangular signs, took precedence over principles.

TSRGD 1964

With minor exceptions, such as the "pass either side" sign, Worboys' recommendations were given effect by The Traffic Signs Regulations and General Directions 1964. The following blue roundels appeared in the 1968 Highway Code:

All but one of these roundels remain in use today. The "pass either side" roundel required the "mostly" before "compulsory" in the explanation to the left. Note the description beneath the roundel with a cycle:

Route for cyclists and moped riders (compulsory)

When doing my Cycling Proficiency Test in the 1960s, it was explained that the white cycle signs on a blue background appeared on cycle tracks which were separate from the main carriageway. If the round sign was present, it required you to ride on the cycle track. If the sign was rectangular, the track was for cycles and mopeds only, but you weren't required to use it. That was the difference between a round and a rectangular sign.

TSRGD 1964 describes the roundel as 

Route to be used by cyclists and moped riders (See Direction 6)

Direction 6 states that the sign is to be used only where there is a traffic order whose effect corresponds to the sign. It doesn't tell you what the traffic order had to say. Worboys is more explicit:

162. Tracks provided specially for the use of cyclists should be indicated by the sign at figure 100 [white bicycle on a blue rectangle]. Nowhere in this country, so far as we know, has it yet been made compulsory, as it often is abroad, for cyclists to use a cycle track rather than the carriageway. If and when Orders are made to this effect, they should be expressed by a similar sign but in the mandatory form of a blue disc instead of a blue rectangle.

Thus, with the exception of the "pass either side" sign, all blue roundels were mandatory signs which gave instructions.

TSRGD 1964 defined the upward-pointing white arrow on a blue rectangle as an informatory sign.

TSRGD 1975: Bus lanes and Mini-roundabouts

Among other things, TSRGD 1975 added signs for bus lanes and mini-roundabouts. 

The blue roundels for mini-roundabouts appear immediately before the mini-roundabout and are substitutes for blue roundels with a left-pointing arrow or chevrons which are placed at the outer edge of the centre of the roundabout. They therefore conform to the Worboys principles.

The signs for bus lanes formed a package, some of which had other uses:

All the upright signs (apart from No Entry) are rectangles. The most important are the blue ones: 

• regulatory: 

  • 653: do not cross the boundary line which separates this side of the road from the contraflow bus lane except to stop to load or unload where this is not prohibited;

  • 654: start of a nearside with-flow bus lane; 

• informatory:

  • 812.1: bus lane starts ahead

The categorisation as regulatory or informatory is taken from TSRGD 1975: upright signs in Schedule I Part II are regulatory; those in Schedule I Part IV are informatory. 

Another change was that the upward-pointing white arrow on a blue roundel (meaning Ahead only) was removed and the upward-pointing white arrow on a blue rectangle was reclassified as regulatory. Its meaning, One-way traffic, remained unchanged. 

These signs therefore breached two principles:

• signs giving instructions are circular, with mandatory instructions being white on blue;

• rectangular signs are used to provide information.

Arguably, the bus lane boundary line and the "BUS LANE" road markings are the real regulatory signage. They are what motorists see and act on. Few (except taxi drivers) are interested in the details specified in diagram 654 (now 959B). This information has been displayed in diagram 812.1 (now 958) some way before the start of the bus lane, informing motorists that they need to move to another lane. 

The regulatory sign 654 (now 959B) is also used after a bus lane has been interrupted by a junction. It then acts both as a reminder to those already on the road and to convey the restrictions to those turning into it.

TSRGD 1981: cycle tracks no longer mandatory

TSRGD 1981 made a subtle but important change to the meaning of the blue roundel with a cycle. It now became:

Route shall not be used except by non-mechanically propelled pedal cycles

No longer were cyclists required to use a track with a circular sign. They (and only they) could use the cycle track if they wanted to. Where a cycle track could be used by mopeds, the plate "and mopeds" would be placed below the blue roundel.

It may help to know that many of these cycle tracks had been built beside dual carriageways in the 1930s and 40s and were formed of cast concrete sections. By the 1980s, they were in poor condition and the last thing cyclists wanted to do was to be forced to use them rather than a smooth tarmac road.

The effect of the change in TSRGD 1981 was to turn the blue roundel with a cycle from a mandatory instruction into a sign which indicated exclusive use.

Exclusive use combines permission (about which a sign is informatory) with a prohibition on its use by others. While Worboys' principles include the use of circular signs for prohibitions, those signs have a red border. Red conveys prohibition, and red is absent from a blue roundel.

TSRGD 1994: More "Exclusive Use" Blue roundels

TSGRD 1994 saw a large expansion in the use of blue roundels. All were conveying the message  of exclusive use. For the signs which related to the carriageway, the plate "Only" was mandated to be appended:

The blue roundels for buses were developed in response to the use of No Entry signs with the plate "Except buses" or "Except buses and coaches". Local authorities used these to create bus restrictions where bus lanes were not possible. These came to be known as "bus gates" as they were usually very short and the first ones did have gates across them (red-and-white poles which lifted as the bus approached). 

The Department has long fought a battle to preserve the respect which motorists show for No Entry signs. If they see "ordinary" vehicles going through No Entry signs, they might well think "if him, why not me?". Buses are obviously different, so TSRGD 1975 defined plates which could be placed below No Entry signs to allow them to be exempted.

The true bus gates had barriers which only opened for buses, so cyclists were prohibited. As bus gates increasingly didn't have gates, cyclists inevitably used them, just as they used ordinary bus lanes.

The Department wanted cyclists to be able to use bus gates lawfully. But it didn't want ever-longer "Except" plates below No Entry signs. Taxi-drivers were also pressing to be allowed to use bus gates. The Department solved these problems by creating blue roundels with pictograms of vehicles (and the word "taxi"). These could be used instead of No Entry signs with "Except" plates.

As the Department recognised that the blue roundels with pictograms might not be understood to imply exclusive use, they mandated the "Only" plate for those which related to the carriageway.

TSRGD 2002: Correcting the Mistake with the Size

TSRGD 1994 had specified the standard diameter for the blue roundel with a bus as 600mm, the same as most other roundels (this was the diameter to be used on 30mph roads). TSRGD 2002 increased this to 750mm. We may infer that the Department came to realise that the sign was harder to read than most, and so needed to be larger.

Despite this change, local authorities continue to this day to place 600mm-diameter blue roundels. As blue roundels may be the only signage which is seen before a bus gate is reached, their size is important. Where they are placed on yellow backing boards, they are as conspicuous as the larger size. Otherwise, as the Traffic Signs Manual comments:

It should be borne in mind that smaller signs are likely to be seen later, and do not become legible until drivers are closer to them, with less time to react.

TSRGD 2016: Roundels Galore! 

TSRGD 2016 was a massive rewrite. It provided local authorities with much greater flexibility in their signage. It also increased to 13 (excluding variants) the number of blue roundels showing exclusive use:

Dropping the "Only" Plate

One element of flexibility which TSRGD 2016 introduced was to allow bus gates to operate for part of the day, as has always been possible for with-flow bus lanes. The regulations make provision for this with plates beneath the roundel showing the times of operation. 

While adding these new plates, the Department did an about-turn with the "Only" plates. Not only were these no longer mandated, they could not be used when new signs were installed. Existing signs could remain, but when they needed replacement, a new "Only" plate could not be placed. 

Despite this, the Highway Code continues to show an "Only" plate below the blue roundel with a bus. This is because the traffic signs are from the 2007 edition. This is evident from the "Road works" sign, which shows "Delays possible until Mar 08".

Conclusions; A Proposal

Blue roundels have come a long way from the Worboys principle of mandatory signs giving instructions. Today, many of them signify exclusive use. This combines  permission (in which a sign informs) with a prohibition on use by others. Prohibitions are indicated by the colour red.

To emphasise the prohibitory nature of the exclusive use, blue roundels at bus gates should be required to be displayed on signal red backing boards:

The effect of such signs can be seen in the pair of images below. They are of the turn from Gas Ferry Road into Cumberland Road, Bristol. 

No longer would a motorist's first impression be of red on the offside (i.e. prohibition) and blue on the nearside (i.e. information). Instead, the red of the backing boards conveys prohibition. At first glance, the overall impression is of red-bordered signs: turning left is prohibited. 

Written 6th November 2025; last updated 14th November 2025