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Safety guard rails

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The guard rail is a safety barrier placed on the sides of the roads. The guard rails are usually placed to stop vehicles from colliding with structures beyond the road edge such as piers, streetlight poles, and any other structures or people . The collision of vehicles with such structures can cause severe damage to vehicles and it can result in severe injury and in some cases the death of the driver. Also, it is very important to use guard rails to prevent the car from falling off the road, this is very common for roads built on mountains. 

The guard rail will reduce the effect of the vehicle impact and it will stop the vehicles and redirect them back to the road in most cases. This will reduce the severity of the crash and it can save the life of car users in most cases. however, it will not give full protection for all driving situations. The performance of impact will depend on many factors such as the speed of the vehicle, size of the vehicle, the orientation of the vehicle at the time of the crash, etc.

The guard rail system consists of three components: the post, the rail, and the end terminal. The post is driven into the soil at the correct location and spacing as per the technical drawing and the recommendation of the system provider. Prior to driving the post, we need to determine the location of posts to conform to road alignment, distance from the road edge and other geometrical requirements. 

Figure no:01

The second component is the rail. The elements of rail may vary for different systems. Figure no:02 shows an example of a rails element. We have a steel block (usually a short channel) fixed to the post and then we have the W beam fixed to the steel block. The fixing of these elements will be done by bolts and washers. The height of the below system from the finished level is 80 cm as shown in the typical detail below (figure no:02). In case of impact, the vehicle will hit the rail (W beam) and this beam will help in keeping the vehicle inside the road and avoid unwanted collision or falling of the vehicle. Also, it will reduce the severity of the collision which may save the life of vehicle occupants.

Figure no:02



Figure no:03


The ability of the guard rail to redirect the vehicle back to the road is determined by conducting crash tests using a special vehicle under control conditions such as speed, angle of collision, ...etc. The system of the guard rail will be tested and if it is found to be crashworthy then it can be used on live roads. 
Figure no:04



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