【正文】 ardrail , is a kind of roof beam type structure fixed with the pillar , depend on the guardrail crooked and out of shape and a pulling force resist the collision of the vehicle. There are a lot of kinds of the roof beam type guardrail , use the most extensive one to be the roof beam guardrail of the wave form . Have certain rigidity and toughness, easy to change after damaging, can lead the sight , the appearance is beautiful . 3)The rigidity guardrail generally points the cement concrete wall type guardrail , is a kind of concrete wall type structure of cement with certain section form , rely on the automobile to climb high , out of shape and rubing to absorb the energy of colliding . The guardrail security high, can prevent two accident effectively, itself difficult to damage, the maintenance cost is low, but have sense of oppressing to go to the vehicle, it is relatively serious to damage the vehicle. Security guardrail of expressway should prevent highspeed vehicle that go from exceed outlet, pass through central authorities is it is it is it to lane , can lead the driver39。s sight correctly to intrude upon to take to separate, make the vehicle get back to normal travel direction, and it is minimum to reduce malignant degree of the accident to. In a word, highspeed highway safety guardrail reduce traffic accident and reduce accident malignant effective measure of degree, but in shouldn39。t set up place of the guardrail set up the guardrail , bee the new barrier instead, it is dangerous to increase the accident. So, should grasp the characteristic of the guardrail to the design of the safe guardrail first and bine the traffic condition of the expressway, on the premise of meeting basic function of the guardrail , select the sui table guardrail form for use, adopt the rational establishment principle. Because topographical terms , make the investment and technological terms to restrain from many kinds of factor, way side have barrier unavoidably, to exceed vehicle of outlet form the potential danger. Way side guardrail set up in be able to reduce accident serious place of degree only, its design principle is confirmed according to people39。s subjective judgement of such factors as class of highway , volume of traffic , vehicle making up and way side characteristic ,etc.. The most ideal guardrail form is that meet function39。s needs as well as the cost is the lowest, and elegant in appearance, and can lead the sight of driving a vehicle . The cable guardrail is suitable for not having evenly no sinking , snow , long straight line , highway section with the special beautiful demand 。 The concrete guardrail is suitable for very dangerous stepping such highway sections as the river bridge , cliff ,etc.。 Wave form guardrail have heavy suitability, suitable for all highway section basically, especially small radius curved dish is it lead highway section of sight to need. Require according to norm and Hunan Province many pieces of highspeed highway safety guardrail design experience, the general way side of highway section adopts the roof beam guardrail of the wave form , the specific very difficult dangerous highway section adopts the concrete guardrail . In a situation that the volume of traffic is big, vehicle go at a high speed, is it cross central authorities separate the situation led to happen, may produce the serious consequence , so, the central authorities separate the width that bring as the important basis of setting up guardrail . Anticollision cushion through absorb vehicle collide energy make vehicle39。s stopping safely, make the vehicle change travel direction, avoid the department and take advantage of personnel39。s receiving facilities of the serious injury. The anticollision cushion is with low costs, have very high security performance . It mainly applies from taking in the middle of not having to bringing and carrying out the transition while having, the usual friendship channelizing island shunts one, has regular barriers when the pilosity highway section of the traffic accident. The anticollision cushion has plastic cushions of systematic anticollision of intermediate layer , fill out such various forms as the sand plastic barrel anticollision cushion , sand bag ,etc.. Practice has proved , the anticollision cushion is a kind of effective facility , it is mainly serious degree which reduces the accident, but not reduce the emergence of the accident. With the rapid development of the expressway of our country, people have improved a lot understanding of the importance of safe guardrail, while building the guardrail, should pare from such many aspects as performance , view and economy ,etc. conscientiously , consider in an allround way. The anticollision guardrail includes the concrete functions of four respects: 1)Prevent vehicle from jump outlet (bridge ) outside, is it bring to separate to central authorities but speech, is it prevent vehicle from pass through central authorities is it take but intrude upon correctly the lane to separate to want。 Meanwhile , is it get off vehicle get out under partial toing the breast board , or break the guardrail to defend。 2)The guardrail should be able to make the vehicle reply to and stop travel direction frequently 。 3)While colliding , the damage to the passenger is the minimum degree: 4)Can lead the sight of the persons who drive . Can be found out from abovementioned functions, the guardrail must have suitable intensity of mechanics and collision in order to keep out the vehicle of rigidity , prevent the vehicle from crossing outside of outlet (the bridge ): Meanwhile, rigidity of guardrail can too heavy, can is it injure or lighten the degree of injuring to protect passenger from better. Real car full size is it is it offend with actual automobile guardrail is it imi