Guardrill tells the roadside and roadside shields that they will prevent vehicles from falling out and falling into the abyss and prevent road accidents and losses. Another use of the Guerrillas is to separate traffic from one highway to another. Various types of these shades are produced, such as two-wave guards and three waves and concrete shields, the same as New Jersey.
According to the rules of safety of the roads of the Islamic Republic of Iran, roadside guards are the three types of guards: flexible guards - semi-rigid protections - rigid shields
Depending on the protective behavior, the collision and deformation rate, the shields are divided into 3 flexible, semi-solid and rigid categories. The full specifications of these shields are given below. The maximum shape variation mentioned in this figure is the results obtained from the NCHRP230 resulting from the collision of a 2-tonne vehicle with a collision angle of 25 ° and a speed of 100 km / hr. Designers should use the following protective features according to their type (flexible, semi solid and rigid) to select the appropriate shield.
Different types of roadside protections (side and center)
Flexible systems:
Double-wavelength cable (with weak base)
Three-wave escape (with weak bases)
Semi-solid systems:
Shaped sponge shell (with weak base)
Two-wake buccal shield (with strong bases)
3-Wave Burning Spiral (with strong bases)
3 wavelengths corrected
Rigid systems:
A concrete casing known as New Jersey
Roadside shields
Parts of the carriage
Flexible shield
A: The 2-wavelength shield system has a very similar antenna to the cable system, while its lateral deformation is much less, so the space required to protect the back is minimized. This type of protection also has the ability to cover vehicles with a weight of 0.8 to 8.1 tons, and in the collision of 1800 kg vehicles with a 28 degree angle and a speed of 95 km / h, a lateral deformation of 2.2 m . The upper limit for servicing this shield is a 2100 kg Van caravan with a collision angle of 24 degrees and a speed of 95 km / hr. At the same time, the system is sensitive to the height of the installation and the earth's gravity and so the installation must be carefully observed in the run.
B: The 3-wavelength shield system with weak bases is quite similar to the W-shaped waveguide. With the difference that due to the greater width of the shield, it covers a wider range of vehicles with different heights and is also less susceptible to altitude changes. Due to the avoidance of shield twist, this system should be rotated frequently from the top and bottom to the base
Rugged half shield
A: Shaft-shaped shaft-shaft system with its weak base gives its resistance to the tensile strength and bending of a beam with a can-cross section. The supports should be designed in such a way as to break the collision near the collision point and move the force to the adjacent pivots so that the power transfer to the pivots is gradual. Vehicles covered by this guard are weighing from 0.8 to 1.8 tons. The upper limit of this system is a caravan with a weight of 2.1 tons.
B: The two-walled dual-walled bumper system with tight legs located between the base and the shield in this system minimizes the chances of a vehicle being torn off by the base and likely to be thrown out of the shaft. Like all systems with strong base, the resistance of this system is obtained from the sum of tensile and bending stresses and flexural and shear stresses of the base. The design must be such that, if the collision strength is such that the bends of the shaft bend, the torn shaft and the vehicle pass through it (instead of being thrown over it). The system easily returns a caravan with a weight of 2.1 tons and an angle of 21 degrees and a speed of 95 km / hr. After the collision, the bases of the damaged part are still capable of responding to intermediate collisions, and therefore there is no need for immediate repairs.
C: 3-walled shield with strong bases is quite similar to type B system, with the difference that it is 3 wavy, slippery and wider, which results in less damage to the shield while handling, and thus the ability to respond to a larger, goes. The height of this 900 mm fence must be adhered to.
D: The modified 3-wavelength shield has 1 snug with a trapezoidal shape that allows the curve to bend when the collision occurs, the bottom edge of the shaft and the curve itself, so that the level of elapsed time during the collision remains perpendicular to the ground. This reduces the chance of launching a vehicle. Such a cover easily covers a typical 820 kg vehicle, a 9100 kg bus (with a 15 ° angle, a speed of 90 km / hr) and a 14500 kg (14 °, 97 km / hr) bus. . This type of protection, if not economical and executive considerations are not considered the best type of protection, and after the collision also leaves the least cost of repairs.
Rigid shield
A concrete system with a variable cross-section, in the event of severe collisions, tends to be reversed and broken, and as a result, the design must be fitted with adequate armature and a sufficient level of protection against the ground. The superior and standard cross-section of this type is known as New Jersey.
This concrete shield can also be used as an intermediate guard and bridges. Depending on the case, it can also increase its height to 2300 mm, even to shield the light of the opposing vehicles or prevent the road from falling down the road. As the concrete protector is designed for conventional modes, the height of 810 mm must be respected, while in the meantime it will properly return vehicles up to 18 tonnes to the original. If the height increases to 1070 mm this system
