Motorways are by far our safest roads for a variety of reasons. Separating vehicles going in different directions, and providing high capacity segregated routes onto and off them greatly reduces the capacity for smashes between vehicles travelling in different directions or from drivers misreading each other’s conduct at a junction. In addition no cyclist or pedestrian is allowed on them, removing the danger of conflict between a fast moving vehicle and a vulnerable person. Motorways are more like railways which also have better safety figures thanks to a ban on all pedestrians and cyclists from proximity to the track, and from seeking to keep trains moving in opposite directions on different track.
The main reasons A and B roads are so much more dangerous lies in three main areas. First, pedestrians and cyclists are allowed, and are very vulnerable to mistakes by drivers or by themselves when coming into conflict with vehicles. Second, many junctions lack capacity and are poorly designed, leading to crashes between vehicles seeking to use the same piece of road to go in different directions. Third, there is scope for vehicles to wander or overtake in the lane coming the other way, leading to potentially very dangerous crashes between vehicles travelling in opposite directions. On a 50 mph road this may mean a 100mph crash.
Most of these A and B rods are under the control of Council Highway departments. They have options under national legislation and grant schemes to make improvements in each of these areas to cut accidents. As with motorways the first necessity is to increase overall capacity to reduce tensions and conflicts between vehicles. Pedestrians and cyclists deserve better treatment through the provision of dedicated cycleways and footpaths that avoid main A and B roads to cut conflict with vehicles. Junctions need review. Wherever possible roundabouts should be used rather than traffic lights, as that ensures all vehicles are heading in the same direction of flow and not meeting head on. Where there are signal controlled junctions they should where possible be reconfigured to provide segregated right hand turning lanes with short filter light phases where traffic is sensed by intelligent lights as waiting. Priority should be afforded with plenty of green light phase for the main road which should allow flow in both directions at the same time with right turning traffic held. On straight stretches of potentially fast road there should be consideration to painting a third overtaking lane where there is sufficient width allowing alternate overtaking by vehicles in opposite directions to cut frustration and dangerous overtaking.