It's no fun travelling on the tube at weekends, is it? There you are, hoping to travel from A to B, but the line you want is suspended "due to planned engineering works". There's always an alternative route, but it's usually either inconvenient or time-consuming or both, and often involves the four-wheeled misery that is the rail replacement bus. Meanwhile services on the line segments that aren't suspended get less frequent trains, which are often packed to rush hour proportions, and what should be a simple day out can rapidly become a nightmare diversionary trek. Sure we're going to get better underground services as a result (or at least some signalling that works and a few shinier tiles), but this relentless inconvenience somehow feels a high price to pay. Plus it'll never finish, will it, because there'll always be more engineering work that needs doing when all this lot's finished. Sorry London, but our weekends are probably permanently blighted for the foreseeable future.
If you're feeling particularly pessimistic, you'll be delighted to know that TfL publish a regular pdf bulletin detailing all proposed tube line closures for the next six months. It makes for grim reading, especially if (like me) you live in one of the areas most affected by current ongoing engineering upgrades. Things are particularly unpleasant on the District and Jubilee lines, with only one single weekend between now and September when they'll be running a normal service. The Hammersmith & City and Metropolitan lines are almost as bad, and there's still no end in sight to part and total suspensions on the Victoria line.
I've summarised TfL's lengthy list in this easy-to-swallow table of weekend tube shutdowns. Every coloured blob indicates a weekend shutdown along part (or all) of a particular line. Now you can plan to be elsewhere as required (or maybe stick to the Waterloo and City line, just to be on the safe side).
Things are worse than this, of course. The London Overground is buggered every weekend between now and the end of the year, and there are also numerous DLR suspensions in the offing (although few of these are yet announced). Add in engineering work on various mainline and suburban rail services, and you might as well stay at home.
And in case you're thinking "it's a lot worse now than it used to be", you'd be right. Here's an equivalent table from four years ago...