Guardrail Schools of Thought

There is not an industry consensus on the benefits of guardrails and how they should be applied. They can catch a derailed truck and prevent it from running off of a trestle. They can also catch a derailed truck and cause a pileup on the trestle that would not have occurred had there been no guardrail.

Guardrails that converge to a point have the ability to catch and realign the most offset of derailed trucks. Without such a guardrail, a truck running at that degree of offset would be quite likely to run off the edge of a trestle. However, a guardrail capable of realigning such an offset truck might wreck the truck in the process the realignment, and cause a pileup. So this has to be weighed against the possibility that an extremely offset truck that might still make it across the trestle even if no guardrail interceded to realign it.

Moreover, if a derailed truck were running offset beyond a certain limit, the knifepoint of the converging guardrails could catch the truck wheels on the wrong side of the guardrail and throw the truck into the ditch.

So there are competing schools of thought about guardrails. Some are made to converge at a point. Others just bend inward slightly, but do not converge to a point. Others simply stub end while running parallel to the stock rails. And sometimes, guardrails are simply omitted. And while a guardrail might prevent a wreck, or might cause one, they are also a maintenance expense, so that figures into the equation as well.