Less Salt, Same Roads? Devon and Somerset Put a Leaner Gritting Regime to the Test

The first hard frost of the 2026–27 season sent gritters out across the South West in the second week of November, but the fleets that rolled down the A38 and the A30 were not the fleets of a decade ago. Fewer vehicles ran, spreaders were calibrated to tighter tolerances, and on a growing number of stretches the load was not conventional rock salt but a brown, faintly sweet-smelling brine cut with molasses derived from sugar beet.

For highways authorities in Devon and Somerset, the shift is presented as straightforwardly good housekeeping: less salt used, less corrosion to bridges and vehicles, and fewer tonnes of chloride washed off the carriageway each time the weather turns. For the ecologists and hydrologists who watch the moorland catchments above those roads, the picture is less tidy. A leaner gritting regime is not the same as a clean one, and the question now is whether the savings are being measured as carefully as they are being claimed.

The case for beet brine

Rock salt works by lowering the freezing point of water on the road surface, but it is a blunt instrument. Dry salt bounces, blows and drifts before it ever dissolves, and it stops being effective at around minus seven or eight degrees. Pre-wetted salt and brine solutions adhere better, act faster and can be applied at lower rates. Adding a carbohydrate-rich by-product such as beet molasses — a widely available residue of the UK's sugar industry — improves stickiness further and, according to the manufacturers, reduces the corrosivity of the mixture.

The operational appeal is obvious. A treatment that stays on the road rather than in the gutter is a treatment that does its job with fewer passes, and fewer passes mean lower fuel use, fewer staff hours and less total chloride applied. Several South West authorities have been running brine trials on selected routes for a number of winters, and the 2026–27 season is the point at which some of those pilots are being assessed against a full winter's traffic, weather and complaint data rather than a handful of cold snaps.

There are limits. Beet-enhanced brine is at its best as a preventative treatment ahead of frost or light snow; sustained sub-zero periods still call for granular salt to break up compacted ice. Molasses residues can also leave surfaces tacky in mild, damp conditions, and there are anecdotal reports from drivers of reduced grip on untreated stretches where brine has migrated. None of this invalidates the approach, but it does mean the chemistry has to be matched to the forecast rather than applied as a blanket substitute.

What the runoff carries

Road salt does not disappear when the thaw comes. Chloride is highly mobile and largely unaffected by conventional treatment, so it moves with meltwater into ditches, soakaways and, eventually, watercourses. In lowland, heavily buffered rivers the dilution is usually enough to keep concentrations modest. On the high ground of Dartmoor and Exmoor, the arithmetic is harsher: steep gradients, thin soils, short travel distances and streams with little capacity to absorb a pulse of saline water.

The biological timing is unfortunate. Many of the species most exposed to winter road runoff are also the ones active in the coldest months. Amphibians moving towards spawning habitat, salmonid eggs incubating in gravels, and a range of freshwater invertebrates are all sensitive to sharp changes in conductivity. Peat adds a further complication: the same waterlogged, organic-rich ground that makes a moor so valuable for carbon storage and flood attenuation is also a chemically active sponge, exchanging ions and holding onto contaminants well beyond the immediate thaw.

It is worth being precise about what is and is not known. The UK has no statutory chloride limit for road runoff comparable to those applied to some other pollutants, and routine monitoring of receiving waters near gritting routes is patchy. Councils hold records of how much salt they spread; far fewer hold records of what arrives in the stream below the road. That asymmetry is at the heart of the current debate, because it makes both the ecological case against salt and the safety case for it unusually hard to settle with evidence.

The safety ledger

None of this would matter much if the alternative were costless. In scattered upland parishes, the gritter is the difference between a passable lane and an isolated household, and the statutory duty on highway authorities is framed around what is reasonably practicable rather than what is chemically ideal. Reducing treatment on minor routes shifts risk onto residents, carers, deliveries and school transport, and it is rarely the busiest roads that carry the most vulnerable users.

The turn towards community salt bins is a partial answer, but it is not a neutral one. Bins that are filled by the council and replenished by volunteers blur the line between public service and self-help, and they concentrate application in the hands of people without calibrated spreaders or forecast data. Over-application around a bin is a common complaint, and it tends to occur exactly where drainage runs straight into a watercourse.

A season worth watching

The more defensible version of the leaner regime rests on precision rather than simple reduction: route-based forecasting, spreaders that adjust to speed and surface temperature, and treatment decisions taken from road sensor data rather than habit. That approach can genuinely cut tonnage without cutting safety, and several authorities in the region are now investing in exactly that instrumentation.

What is missing is the other half of the ledger. If councils are to claim an ecological dividend from using less salt, they should be able to show it — with conductivity monitoring in a handful of representative moorland catchments, with records of application rates by route, and with an honest account of which roads have been left untreated and why. The 2026–27 winter is the first in which the technology, the policy interest and the political pressure to justify spending all point the same way.

Until that evidence exists, the beet brine experiment deserves to be judged on its merits rather than its marketing. Spreading less salt is very probably a good thing. Proving it, and proving that the saving has not simply been moved from the carriageway to the stream, is the harder and more useful task.