@chdot: They have the option of doing nothing??
The RAIB isn't a court of law, or a regulatory body. Its role is to investigate accidents and make recommendations about steps that might be taken to avoid them happening again. The RAIB cannot force anyone to follow their recommendations. The article is about the RAIB's report which was published today (you can have a read of it here if you want to) - whether anything further might come of it e.g. from the Office of Road and Rail to enforce compliance with the RAIB's recommendations is another issue. (You will I'm sure have noted the reference to the investigation being carried out by the Scottish Fatalities Investigation Unit under the aegis of the procurator fiscal, so legal action may yet be in the offing.)
So yes, in that sense absent any further action by body with the relevant authority Edinburgh Trams do indeed have the option to do nothing. But taking that option would certainly count against them in the event of another, similar accident in the future. You will again have noted their statement in the article, that they have already addressed the RAIB's recommendations regarding the audibility of their trams' warning devices, and reviewing risk factors associated with off-street pedestrian tram crossings, and a plan is in place to implement additional risk control measures.