Half of all fatal road crashes occur on one-tenth of Britain's roads, according to the Road Safety Foundation charity.
Its report, covering 28,000 miles of A-roads and motorways, says on average Scotland has the highest-risk highways, followed by parts of northern England.
The most dangerous individual road was the A537 between Macclesfield, Cheshire, and Buxton, Derbyshire.
The charity wants government spending to be targeted at improving safety on the most dangerous roads.
Its report, entitled Saving Lives for Less, suggests the high cost of emergency services and hospitals could be avoided by spending small sums in accident blackspots.
The foundation is the British arm of the European Road Assessment Programme, the sister organisation of EuroNCAP, which measures car safety.
It examined accident data relating to roads across Britain. Among its conclusions were:
- A third of all fatal and serious crashes happen at junctions
- Single roads carry six times the risk of motorways and twice that of dual carriageways
- One-in-four fatal or serious crashes on A-roads or motorways involves a motorcyclist
- There was a 5% reduction in the number of fatal crashes on such roads in the past three years
- West Midlands is the safest region
The most improved road was named as the A40 between Llandovery and Carmarthen.
Improved junctions and markings, along with resurfacing with high friction, anti-skid treatments, saw the number of serious accidents fall from 27 between 2003 and 2005 to seven in the following three years.
Foundation director Dr Joanne Hill said such simple, well-planned engineering measures were relatively inexpensive.
"Not only can Britain reduce road deaths and serious injuries but, by targeting a relatively small mileage of high-risk roads, we can do so with good economic returns.
"Too often we pay for emergency services, hospitals and care for the disabled rather than taking easy steps to put road design faults right."
A quarter of the road length in the survey was in Scotland, where one in nine fatal crashes occurred.
On average ratings across all the regions, Scotland had the most dangerous motorway and A-road network, with 12% in the higher risk categories.
But when it came to the highest risk individual roads, none of the Scottish ones made Britain's top 10.
The study, using figures from 2006 to 2008, divided the road network into "significant sections" of various lengths.
It then calculated the risk by dividing the number of fatalities on a given section by the number of kilometres driven on it.
The report said the A537 through the Peak District, known as the Cat and Fiddle, had severe bends, steep falls from the carriageway and was edged by dry-stone walls or rock face for almost all its length.
Fatal and serious collisions on the route - popular with tourists, goods vehicles and motorcyclists - rose from 15 in the three years to 2005 to 34 between 2006 and 2008.
Most crashes happened at weekends during the summer in dry, daylight conditions.
The report also names the highest-risk roads when crashes involving motorcyclists are excluded, with a stretch of the A18 in North East Lincolnshire topping the list.
Most of these roads are single-carriageway A-roads, with nine of the 10 in northern England.