Why Serious Crashes Rose 33 Percent on One Smart Motorway After Conversion

Serious incidents on the M3 between junctions 2 and 4a rose by a third after the stretch was converted to an all-lane running smart motorway, according to National Highways’ own Post Opening Project Evaluation reports. That single figure sits at the heart of a wider verdict on the smart motorway programme: 13 out of 16 completed schemes failed to meet the value-for-money targets set for them when the government approved the spending.

Smart motorways were sold to drivers and taxpayers as a way to add capacity without the cost of widening a road, by converting the hard shoulder into a running lane and relying on cameras and technology to spot broken-down vehicles. The removal of the hard shoulder is exactly what turned a routine breakdown into one of the most frightening situations a driver can face: stationary in a live lane, with traffic passing at up to 70mph, and no guaranteed refuge nearby.

What the Evaluation Reports Actually Found

Post Opening Project Evaluations are National Highways’ own assessment of whether a completed road scheme delivered what it promised, measured against the original business case. Of the 16 all-lane running conversions evaluated, only three met their value-for-money target. The other 13 cost more, delivered less benefit, or both, than the government was told to expect when it approved the spending.

The M3 evaluation is the clearest single data point showing what went wrong on the safety side. Between junctions 2 and 4a in Surrey and Hampshire, serious incidents rose by 33% after the hard shoulder was converted into a running lane. That is not a marginal statistical wobble. A one-third increase in deaths and serious injuries on a specific, measurable stretch of road directly contradicts the safety case originally used to justify the conversion.

National Highways has consistently pointed to network-wide figures showing that, taken as a whole, all types of smart motorway have a lower rate of deaths or serious injuries than a conventional motorway. Both things can be true at once: an average across the network can look acceptable while individual converted stretches, including one as heavily used as the M3, perform markedly worse than before.

Government Already Pulled the Plug, But Existing Roads Remain

The government cancelled all future smart motorway construction in 2023 after sustained safety concerns and political pressure, meaning no further hard shoulders will be removed under new schemes. That decision does not undo the roads that already exist. Around 475 miles of smart motorway remain in operation across England, and drivers using them today are relying on the safety mitigations National Highways has retrofitted rather than a hard shoulder that was there from the start.

The retrofit programme itself has been substantial. Following a £390 million investment agreed after a Transport Select Committee report on the rollout and safety of smart motorways, National Highways added more than 150 additional emergency areas across the all-lane running network, a commitment it says was completed in spring 2025. That work means there are now around 50% more places to stop in an emergency compared with January 2022. Stopped vehicle detection technology, which is designed to spot a stationary vehicle and close the lane automatically, now covers more than 95% of all-lane running sections, typically triggering within seconds of a vehicle stopping.

The Gap Between the Promise and the Experience

AA president Edmund King has criticised the delayed publication of the POPE reports as an example of a body trying to bury difficult findings rather than confront them directly. The AA has called for a return to traditional road widening, with a permanent hard shoulder restored on all major routes, arguing that the cost overruns and safety compromises of the smart motorway experiment make the case for the original approach.

For drivers, the practical question is less about the political history and more about what to do if disaster strikes on a stretch without a hard shoulder. Emergency Refuge Areas on all-lane running motorways are now spaced at a maximum of one mile apart on retrofitted sections, though older, unretrofitted stretches can still have gaps of up to 1.6 miles, meaning a driver in trouble could still need to travel some distance before reaching one.

What Went Wrong With the Numbers

The original business case for converting hard shoulders into running lanes rested on a simple trade: a cheaper way to add motorway capacity than building new lanes from scratch. The POPE reports show that trade did not hold up once real costs and real safety outcomes were measured against the projections used to win approval. Budgets for several schemes grew substantially once technology problems emerged and once the initial emergency area spacing proved too wide, forcing National Highways to go back and retrofit refuges that should have been built into the original design. Comparing the final cost of an all-lane running conversion with the cost of building a brand new lane, with a permanent hard shoulder retained, narrows the gap that originally made the smart motorway option look like the obvious choice.

The safety case has followed a similar path from confident promise to contested reality. Early modelling assumed that stopped vehicle detection technology would close a lane fast enough to prevent a stationary car ever becoming a hazard. The M3 figures suggest that assumption did not translate cleanly into practice on every stretch, whether down to technology limitations, driver behaviour, or a combination of both. Until National Highways and independent analysts can point to a specific reason why the M3 stretch performed so differently from the network average, individual drivers are left to judge a safety case that looks solid in aggregate and considerably less solid on the exact road they are about to use.

How to Fight Back

Know the signs before setting off. Emergency Refuge Areas are marked with blue signs featuring an orange SOS telephone symbol and are roughly the length of a football pitch. Knowing what to look for in advance, especially on unfamiliar routes, reduces the panic of searching for one in an actual breakdown.

If a breakdown happens in a live lane and a refuge area cannot be reached, put hazard lights on immediately, and if it is safe to do so, exit the vehicle through the left-hand doors and stand behind a barrier, away from moving traffic. Call 999 straight away rather than waiting to call a breakdown provider first, as National Highways’ control room needs to close the lane using the overhead gantries.

If a refuge area is reached, use the orange SOS phone inside it rather than a mobile, as it connects directly to the National Highways control room and automatically identifies the exact location, which speeds up both a lane closure and the arrival of help.

Check the specific stretch before a long journey. National Highways publishes details of which sections have been fully retrofitted with additional emergency areas and stopped vehicle detection, and which are still awaiting upgrades, through its smart motorways evidence stocktake pages.

Report near misses and defective technology. If stopped vehicle detection fails to trigger, or an emergency area is blocked, obstructed or poorly signed, reporting it to National Highways directly adds to the evidence base that shapes future safety investment, especially on stretches like the M3 where the data already shows a problem.

Support calls for independent scrutiny. The pattern of 13 out of 16 schemes missing their value-for-money targets, combined with a documented rise in serious incidents on at least one heavily used stretch, is the kind of finding that campaign groups and MPs use to push for continued monitoring rather than treating the 2023 construction ban as the end of the conversation.

The smart motorway programme has already been halted for new roads. What the POPE reports make clear is that halting construction did not fix the roads that were built under the old approach, and the M3 figures suggest at least one of them is measurably more dangerous today than the conventional motorway it replaced.

Sources:

• National Highways: National emergency area retrofit
• National Highways: Smart motorways evidence stocktake
• Transport Committee: Rollout and safety of smart motorways
• AA: Emergency refuge area guidance