Re: Derail and how common?

Minor de-rails are not terribly un-common on small NG tourist lines and there are a number of reasons why they occur.
I have some years of experience now with safety and industrial accident investigation and would like to share some thoughts on the subject of derailment.
Usually, there is no single cause of any industrial accident - 90% of the time accidents, such as derailments, are due to a convergence of circumstances, most of which are preventable with proper attention to detail (proper safeguards in place and equipment suitable for the use intended, etc.), training of personnel and timely (preventative) maintenance of track and equipment .
Recent reported de-railments would be regarded in the safety program as "near misses." A "near miss" is a reported incident which, when investigated properly, has the lead up characteristics/factors of a serious accident, but does not result in the loss of life or limb or measurable property damage.
All "near misses" should be subject to intensive and objective investigation to determine all lead up factors, as it has been documented time and time again, many serious lost time or catastrophic accidents have been pre-cursed by one or more "near misses." Casual investigation - or the "Oh, Well" attitude is not acceptable in any industry any longer.
Most industrial safety programs not only have carefully laid out instructions for proper investigation of all accidents and near misses, they also require that the loss prevention managers from their respective insurance agencies are brought into the circle and consulted. I had the pleasure to work with several of these folks and they tend to be very positive and extremely helpful. In addition, there is a vital portion of most safety programs that require immediate mitigation of all lead up factors. This part of the program always includes repair and modification of equipment, changes in procedures and, most important, behavior modification (training) of personnel. None of these should be overlooked in the quest for a flawless safety record.
A key factor for recent reported de-rails is the serious nature of the "near miss." Most NG de-rails are of the type where the maximum damage is to drop a car wheel in a switch. These are relatively minor and easy to re-rail. A locomotive de-rail requires a higher level of concern due to its weight, role in pulling/pushing cars, and potential for catastrophic failure and environmental damage. A small switching de-rail of a locomotive can pass as minor incident after a complete investigation with some basic repairs, tailgate safety talks and some procedural considerations. Where full safety follow-up is absolutely critical would be a case where a locomotive derails with all trucks, pulling a fully loaded passenger or freight train on a steep hillside, detaching and bending the guard rail (an excellent precautionary piece of engineering) and riding the ties for 20 or more feet. I would expect a professional and safety conscious operation to do a complete safety work up per their safety program before they ran another train on that piece of track. It would not be uncommon now for all operating personnel to be drug tested immediately following such an event, particularly if the incident involved property damage of any kind.
Safety first,
Karell