RATP anounces RER B closures from CDG into Paris
 

Service from CDG into Paris on the RER B will be dramatically altered on the following dates:

20 Oct
1 November through 4 November

Portions of the tracks will be closed and alternate (much less convenient) routes are purposed. If you plan on going to/from CDG and Paris on these dates, strongly consider taking a taxi or one of the bus alternatives, i.e. le Bus Direct or the Roissybus.

Not only that -- all trains are cancelled out of Gare du Nord tomorrow October 20th. Even the Eurostar and the Thalys are not operating in the evening. This is due to a total change of rail command post during a 19 hour period. 300 rail employees will be working on the project all day. All should be back to normal Sunday 21st at 5 a.m.