Here we need to know about mechanical strength of LHB.
LHB coaches are made up of steel whereas in icf iron is employed. The elastic strength of steel is greater than icf.
Now, let's suppose a case: Two trains one lhb and other icf meets a head on collision(both are at 100kmph) . The higher momentum of heavier icf coaches will lead to deformation and major damage of icf coaches whereas LHB ones will suffer 60% lesser damage due to it's elastic strenght and property to absorb the impact applied.
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Thats why mega structures have steel bars due to its elastic strenght. In earthquake steel will absorb the impact and will show elasticity rather rigidity which will save the buildings to some extent.
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In last of all these, i must ask you a question that why ICF is not allowed above 110kmph and LHB goes upto 160kmph, Hybrid LHB (which icf with lhb shell) has potency to speed upto 120kmph?