How wide can you go on the road…and stay within the law?

It’s a time of year when self-propelled forage harvesters are roaming the countryside. Over the coming months, it will be the turn of combine harvesters to navigate the highways and byways.

These machines are unusually wide – certainly when compared to most other road-going vehicles. With increasingly large front tyres, they haven’t gotten any narrower in recent times. So, how wide can agricultural machines go – and still remain within the law?

The most recent guidance from the Road Safety Authority (RSA) stipulates a maximum road-going width of 2.55m for a “tractor”. However, this increases to 2.75m for what it classifies as a “large tractor” – i.e. with an unladen weight exceeding 7.25t.

Most notably, the allowable road-going width increases further – to 3.5m – in the case of “self-propelled agricultural machinery”. This category clearly includes self-propelled foragers and combines.

This info-graphic (below) shows the data more succinctly.

Source: RSA

Interestingly, the 3.5m width stipulation also applies to “tractors with flotation tyres or a dual-wheel system”.

A limit of 3m applies to “fully-mounted equipment and interchangeable equipment”. This measure presumably reflects the preponderance of 3m-wide equipment in use by Irish farmers and contractors including, for example, an especially large population of mowers and power harrows of this size.

Image source: Shane Casey

Talk of road-going widths aside, there is also some lingering confusion regarding the use of flashing amber beacons on tractors.

On this topic, the RSA referred us to an ‘official’ document, which essentially comprises FAQs (Frequently Asked Questions) outlining lighting and visibility laws for agricultural vehicles.

Therein, the following two questions (from a much broader list) are posed and answered:

Are all tractors required to be fitted with a flashing amber beacon?

  • Yes; even vintage tractors unless they’re only taking part in vintage rallies or being used for display purposes.

When should work lamps / ploughing lamps be used?

  • Work lamps, commonly referred to as ‘ploughing lamps’, are fitted to agricultural tractors and self-propelled agricultural machinery for off-road use only (e.g. in the farmyard or field) to give extra visibility to perform specific tasks;
  • These lamps should be switched off when the vehicles are in use on a public road. The regulations ban white lights being used on the rear of a vehicle on public roads as they can confuse and dazzle other road users.

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