A frontal collision is very severe compared to other types of road collisions. Vehicles moving at highway speed only take a few seconds to cross the median and collide with vehicles on the other side of the lane. Medium barriers are effective in physically separating opposing traffic streams from a highway. It also helps prevent vehicles from accidentally moving into the opposite lane and prevents pedestrians from crossing the road in dangerous places. In 2006 there were 821 medium crossover accidents resulting in fatalities on the US national highway system alone.

Factors that influence the selection of a barrier system are the type of vehicles involved, the geometry of the road, and the potential severity of any frontal collision incident. In most places, a standard barrier capable of redirecting vehicles to the correct area would suffice. However, in locations with complex geometry, harsh environmental conditions, heavy truck traffic, and high traffic volumes and speeds, a high-performance barrier is necessary.

There are basically three categories of medium barriers. Are detailed below,

Rigid barriers

The most common type of medium barrier in use today are concrete barriers.

Pros:

– They are widely used due to their maintenance-free characteristics, low life-cycle cost, and safety performance.

– They are very effective in avoiding cross-vehicle collisions in accident-prone regions with high traffic volumes and speed.

– They can also be used in areas where the necessary widths are not available to install other types of barriers.

– The Jersey barrier is a modular concrete barrier that allows vehicles to collide on its sloping underside, turning it back in its original direction.

Cons:

– Comparatively, the installation cost of rigid barriers is high.

Semi-rigid barriers

Otherwise it is called a railing or guide. These rails are made of metal and are collected in segments supported by posts or blocks.

Pros:

– Unlike rigid barriers, semi-rigid barriers are designed to absorb more energy from the impact and the whole assembly moves or deflects during the crash. Therefore, less damage to the vehicle.

– The installation cost is lower.

Cons:

– They are only suitable in areas that are not neglected and have good soil condition.

– The cost of repairing after an impact is high.

Cable barriers

It usually consists of several cables that are connected to each other on a series of poles.

Pros:

– It is the most versatile and tolerant barrier system to minimize medium cross collisions. This absorbs most of the impact energy and reduces the forces exerted on vehicles and their occupants.

Cons:

– Considerable time and cost must be spent on maintenance, putting motorists and workers at risk during each repair.

The other factors that are considered before deciding on the type of barrier are the alignment of the road, the accident history and the number of lanes.