Last updated 14-12-2019, fixed links 9-3-2024

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N and R numbers on signs

N and R numbers are in principle signposted in green (national routes) or white (other routes).

National and regional routes in green and white

Recently changed R numbers sometimes appear in yellow.

R458 is the former N18

In many cases, especially in cities, they are missing. This page gives statistics based on more than 2000 observations.

Rules and method

Data points and categories

One data point is the indication or absence of an A or B number coming from one direction.

Random samples were taken of junctions between A and B roads in the United Kingdom. A large number of cases were categorised in the following ways:

• 1. From category: Primary National routes, Secondary national routes and Regional routes (3)

  2. To category (3)

  3. Same or different number (2 possibilities) - Going from highway X to another highway Y is distinguished from continuing on the same highway.

  4. Continue straight or turn off (2)

  5. Towards a road (section) with a single number or with several numbers (2)

This gives 72 possibilties. To illustrate this, consider the fictitious situation below:

The N11 is a Primary National route running east-west, and the R112 is a Regional route that joins the N11 to the east.

There are 8 different cases here:

About 280 junctions were analysed this way giving about 2100 data points. Data was recorded per case: e.g. if there are four possible turns to a different number at a junction and three of these are indicated, then indicated=3 and total=4 are recorded, not each individual turn separately.

Google Streetview was used for all junctions.

Some rules

1. Multiplex numbers

   When a route follows along with another route, this is generally indicated between brackets in Ireland as in the United Kingdom. Example:

N55 multiplex with N4 between brackets - N5 is an indirect reference

  Any number indicated with or without brackets is counted as a success.

2. Visible signs

1. A sign that is aimed at traffic coming from the other side only and would only be visible to a driver looking back is not counted.

2. Using this principle, at roundabouts without advance directional signs, only signs to the left and straight are taken into account, as a driver can not be expected to contiue on the roundabout to see signs on the other side.

3. In general all signs visible to the driver in the given direction are counted, including signs aimed at a crossing road, e.g.

This sign is mostly aimed at traffic coming from the side road but is visible to drivers on the N59.

In many cases road numbers only appear on advance directional signs, not on signs at the junction (if they exist at all), but these are counted as indicated.

3. Straight vs. turn

A maneuver is considered to be straight on if a vertical arrow on a sign or a lane indication indicates straight on, even if the angle is not exactly straight. If one is required to use an indicator when driving the given maneuver, it is considered turning off.

4. Bushes

Some signs are partly behind bushes in Streetview, this is ignored and road number indications visible on any pano are counted as success.

In the tables below, green is used for Primary National routes, orange for Secondary national routes and yellow for Regional routes.

Nationwide results

Note: the category 'same number' is obviously impossible when going from one class to another.

Some county specific data

Since only a small number of data points per county is available, only the combinations from-to road classes are computed.

In many counties only a subset of combinations is possible. For example, there are no Secondary National routes in Leitrim and in Offaly they have all been replaced by motorways. In Dublin there are Primary and Secondary national routes but they never meet (since the downgrading of the N82).

The overall percentages per county for all road classes together are (click to see entire diagram): 

At first sight it is remarkable that Secondary routes are better signposted than Primary routes, but this can partly be explained by the fact that most of the National routes in Dublin, Cork and Limerick, where road numbering is generally badly signposted, are primary. Excluding Cork, Dublin and Limerick from the overall totals for National routes we get 94.7 % for Primary routes and 95.6 % for Secondary routes, i.e. less than one percentage point difference.

In Dublin city, most National roads have been downgraded to Regional roads, but R numbers are barely signposted and instead Junction numbers and indirect references to N numbers appear, e.g. 

Junction 10 on the R118 with indirect references to National roads

The low percentage for Regional roads is mostly due to the overrepresentation of Dublin in the sample. Excluding Dublin, the percentage of indicated numbers increases from 73.1 to 80.1 %.

The low score for Kilkenny is due to two things:

The N10 is only signposted towards the south. In the other direction, there is almost always only an indirect reference to the M9. This may come from the time when only the part of the M9 to Dublin was completed, since the N10 also leads to the M9 in the south.

In Kilkenny city, R numbers are barely signposted.

Some more aggregations

Each of the criteria is aggregated below.

Whether a road turns off or not and whether the same or another route is indicated makes practically no difference, while the probability that a number is indicated together with another number is much lower than a number on its own, which is not surprising.

Marcel Monterie

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