viraptor:because all the important engineering work can't be done during the week - that's what weekends are for
During the weekends a lot less people travel. Ergo engeneering that will likely cause delay is best done in weekends
People usually have more time during weekends. Delays will be less irritating for them. Ergo engeneering that will likely cause delay is best done in weekends.
The netherlands had a very good functioning railway system until 10 years ago. In the boomin end-90's economy and stock exchange the government decided to privatize public companies (which the railways were back then). To make more profit, the direction of the NS (the railway company) cut back on a lot of investment (e.g. maintanaince, new trains, railway expansion). So after a few years everything grinded to a halt with especially frequent long delays.
It's getting a little better now luckily. I take the train 2x5 times a week and have a delay of 30+ min less than once a month. 5-10 minutes delays happen about twice a week, but I calculate those into my shedule and I understand those can happen.