Drainage Components
There are a number of different components that make up the highway drainage system. The most common components are :

• Gullies
• Grips & gouts
• Roadside Ditches
• French / Counterfort Drains

Gullies
These are what most people refer to as 'highway drains'. People are often concerned that gullies are blocked because they appear to be 'half full' all the time. This however, is entirely normal because gullies are designed with a sump that collects silt and other solid material - a pipe, located above the sump, drains the water away. If a gully is full up to the top then this is a different matter and you can assist the Authority by reporting it.

We aim to clean the silt out of every gully at least once a year and appreciate that perhaps in some cases this is not enough. To try and improve the situation the Authority has purchased its own gully emptying fleet and is now better placed to deal with troublesome areas.

Grips
This is simply an opening that channels water into a drainage pipe or roadside ditch. A grip can simply be a channel cut through the earth of a road side verge - this type of grip is also called a gout.

The Pipes connecting gullies and grips generally operate efficiently with no need for regular, routine maintenance. There are occasions however, when mud and leaves deposited on the road wash into the drainage system causing blockages. Blockages are cleared by employing a high pressure water jetting machine.

Roadside Ditches
Maintenance of these is generally the responsibility of the owners of the land adjacent to the highway. However Monmouthshire, as the Highway Authority, has taken the pragmatic view that ditches (and gouts) are an essential component of the highway drainage system and are therefore cleared on a cyclic basis.

French & Counterfort Drains
These are established to prevent water getting into a road's foundations. Essentially they are deep, narrow channels cut into roadside verges and embankments and filled with stone. Water passes through the stones  into a pipe at the bottom of the drain. French drains normally run parallel to the road in the verge while Counterfort drains are usually provided on the sides of  embankments - these are also referred to as 'herring-bone' drains.