As my year comes to a close on the railroad, I recently has a discussion with a senior manager about ALARP, a new acronym for the RR. The manager wanted to know more about using the Hierarchy of Controls to reduce risks; more specifically, how we would reduce the SEVERITY of the consequence of an event. So I used the scenario of…
A train striking a vehicle at a RR Crossing. The amount of energy involved in these events is huge; unfortunately, a RR can not rely on the public to behave properly at all crossings. So using the laws of physics, the easiest way to reduce the energy involved in these events is to require the train to STOP at all crossings.
But is that ALARP? ALARP stands for As Low As Reasonably Practicable.
So we must ask, is stopping all trains at all crossings Reasonably Practicable?
It would certainly reduce the energy involved in crossing accidents, dramatically impacting the severity (as well as frequency/likelihood) of these types of incidents – BUT is this Reasonably Practicable? What kind of impact would this have on the business?
We may successfully reduce the crossing accidents’ severity (and frequency), but we would put the RR out of business.
So we have established a “floor” in our risk assessment. Remember, there is no such thing as “no risk.”
So we begin to work our way up the risk scale to, let’s say, 10 mph. We would still get a major reduction in energy at this speed, and we would increase the efficiency of the railroad from the STOP plan. But is ten mph ALARP for a RR?
We can’t forget that whatever speed we end up on, controlling the speed is an ADMINISTRATIVE CONTROL that is placed on the train engineer. We will assume the general public will not abide by the signs/warnings (i.e. administrative controls). But these days, most trains these have Positive Train Control (PTC), which is very similar to what we call a Safety Instrumented System (SIS). If we could use this SIS to control speed, along with administrative control, it would improve our safety considerably.
We could also consider crossing controls that attempt to control the public from crossing the tracks as a train approaches. I would not give much consideration to these controls unless they were beefed up considerably, as I see tons of people driving around arms and actually getting stuck inside the arms as a train approaches.
But this is a very informal discussion on how we can view “risk reduction” by reducing the severity of crossing accidents.