Computer model: Because of the cost of full-scale crash tests, engineers often run many simulated crash tests using computer models to refine their vehicle or barrier designs before conducting live tests.These tests are performed to show the advancements in crash-worthiness. Old versus new: Often an old and big car against a small and new car, or two different generations of the same car model.Roadside hardware crash tests: are used to ensure crash barriers and crash cushions will protect vehicle occupants from roadside hazards, and also to ensure that guard rails, sign posts, light poles and similar appurtenances do not pose an undue hazard to vehicle occupants.More recently, dynamic rollover tests have been proposed in lieu of static crush testing (video). Roll-over tests: which tests a car's ability (specifically the pillars holding the roof) to support itself in a dynamic impact.Pole-impact tests: A difficult test which places a large amount of force on a small proportion on the side of the vehicle.Side-impact tests: these forms of accidents have a very significant likelihood of fatality, as cars do not have a significant crumple zone to absorb the impact forces before an occupant is injured.These are usually conducted at 15-20% of the front vehicle structure. This is the most demanding test because it loads the most force onto the structure of the car at any given speed. Small Overlap tests: this is where only a small portion of the car's structure strikes an object such as a pole or a tree, or if a car were to clip another car.Insurance Institute for Highway Safety (IIHS), EuroNCAP, Australasian New Car Assessment Program (ANCAP) and ASEAN NCAP. This type of testing is done by the U.S.A. These tests are often realized by cars turning into oncoming traffic. These are important, as impact forces (approximately) remain the same as with a frontal impact test, but a smaller fraction of the car is required to absorb all of the force. Moderate Overlap tests: in which only part of the front of the car impacts with a barrier (vehicle).SUVs have been singled out in these tests for a while, due to the high ride-height that they often have. Vehicles usually impact a solid concrete wall at a specified speed, but these can also be vehicle impacting vehicle tests. Frontal-impact tests: which is what most people initially think of when asked about a crash test.