Were the train conductors, railway workers, etc. who were involved in transporting Jews to concentration camps tried for crimes against humanity similar to the Nazis in the Nuremburg Trials? If not, what happened to them?

For the most part, major Holocaust-related trials have either been high-level players (Nuremberg Trials, Subsequent Nuremberg Trials) or camp staff (Frankfurt Auschwitz Trials). But there were more than 100,000 collaborators prosecuted across Europe in the post-war period, but I know of only one associated with railways: Jean Berthelot, the Vichy government's Secretary of Transport and Communications, who was sentenced to two years in jail. (See The Wiener Holocaust Library for more on post-war trials in general.)

For a deep dive about the experiences of railway workers who were involved with transports, Broch's Professionalism in the Final Solution: French Railway Workers and the Jewish Deportations, 1942-4 is an essential read.

So that's the individuals...but what about the railways themselves? Over the past 20 years, a number of lawsuits have been brought against them.

SNCF, the French railroad, was sued in US court in 2001 for its involvement.
SNCF was sued again by the Lipietz family in 2001 and awarded a judgment in 2006; it was unpopular and was overturned in 2007.
In 2012, the German railway, Deutsche Bahn, hired US lawyers in anticipation of lawsuits.
In 2015, Deutsche Bahn was sued over its involvement.
In 2019, Dutch railway Nederlandse Spoorwegen agreed to pay survivors and their descendants compensation.

At this point, it would be difficult for any remaining workers to be prosecuted; most of the individual perpetrators who have been brought to trial in the past few years have been found unfit, died before sentencing, etc. There may indeed be other railway staff among the 100k+ put on trial after the war, but it would be difficult to comb through all these records. (If someone else knows of others, please reply and share.)