On reflection, I should have expected that that CASTOR reference may not recall the background information I have on the issue - and that the protests may have been presented with in a sensationalist/biased/lacking in context way. So here is a summary.

Precedents
Preceding the anti-CASTOR protests was a long-running court and protest battle between locals and activists on one hand and the industry and the (federal) state on the other over the designated nuclear waste storage site. On one hand, there were (and are) more than serious doubts about the stability and water-impermeability of the silty ground near the Elbe river. On the other hand, the original site designation was more informed by going for the least resistance: to a sparsely populated area in an area right next to the Iron Curtain. As the years passed, the state repeatedly applied the method of promising an overview or let-up, then some time later presenting a fait accompli. The initial anti-CASTOR protests in fact aimed at preventing the activisation of the facility.

CASTOR containers and transports
The security measures, citing terror, technical accident and protest concerns, included and include:

1. The containers themselves: super-stong metallic containers designed to resist all kinds of chemical effects, extreme acceleration/deceleration (they were tested by throwing them out of airplanes, also in train crashes), electricity etc. (Later though, it was found that hard stresses and wear do cause structural damage on them.)
   
2. They are put in long trains with multiple locomotives which also serve as buffer. The locomotives are diesel-powered thus autonomous (and are fitted with protective gear themselves).
   
3. The routing of the trains isn't announced in advance, multiple lines are drawn up.
   
4. Along the possible lines, police checks for any hindrances the day before.
   
5. When the train comes, all other rail traffic is stopped on the section so that collision is not even possible. To limit the railway's inconvenience and to make the approach less apparent, the train is often routed along sparsely used or disused branchlines (which paradoxically make the protesters' 'job' easier, most major blockades happened in such lines).
   
6. The train is 'preceded' by a helicopter, which again checks for hindrances.
   
7. Along the route when the train passes through, policemen are called out to control the area in a half-hour or so, again checking for any hindrances.
   
8. The train advances at a slow speed. On some critical spots, at walking speed, surrounded by walking policemen.

Anti-CASTOR protesters' blockades
Most protests were/are organised by a loose network of varous NGOs and local initiatives. The bulk of the protesters, who included all kinds of groups from senior clubs to school classes with their teachers, held up the trains with 'human barricades': people staging a sit-in, a protest rally or rushing up in masses in front of the train, or climbing on the train where it stops. Policemen then carried people off one by one, and on to the next obstacle -  which often were the same people walking forward a few hundred metres.

I note that the police operation was provided by the Land [~federal state] and to a lesser part federal organs free-of-charge to the energy giants, thus the first and biggest protests were also with the hope that the Land (Schröder's BTW) will be the weak link who will refuse to further shoulder the costs. (Alas that wasn't to be.)

Both some locals and activists groups also made more serious obstacles: concrete sleepers, tractors, removed rails, people chained to rails. These were/are usually surrounded by a sit-in, preceded by one or more group of protesters who signal to the train, or warning tables planted ahead. Participants of such actions aimed/aim to be arrested and tried (and usually signed/sign statements in advance). Even such blockades are usually removed in minutes to an hour. (The longest blockade was caused by members of the traditional anti-nuclear group Robin Wood, who prepared a concrete cavity in the tracks of a disused line on the rightly guessed route, and chained-concreted the hands of three members into it the night the train came, causing a daylong delay.)

The dangerous "wild" protests
Unlike the aforementioned public activist groups, some anonymous idiots applied truly dangerous hit-and-run tactics: obstacles placed without warning groups or tables behind curves, obstacles placed the day before on branchlines, or hours before on mainlines, anchors thrown at catenaries.

These "wild" actions (if they are, see below) were both dangerous and unprofessional. For, they chiefly hit normal trains - and them hard, unlike the slow-moving quatro-secured CASTOR trains. Especially the last: the CASTOR trains with their diesel locos aren't affected by power losses, nor do they have pantographs for the anchors to get struck in and tear down the catenary, while regular train drivers have been hurt by the anchor cable itself.

On the other hand, we cannot know for certain if concrete plates on the rails or a throw-anchor attack is a "wild" anti-CASTOR protest. For, receiving less media attention, but troubling the German and other railways and their workers, such incidents happen with a worrying regularity, and culprits are almost never caught - probably a rather extreme form of teenager prankstery.

_{*Lunatic*, n.
One whose delusions are out of fashion.}