The problems are ongoing from a few weeks ago. The weather was quite mild, followed by a big storm which brought almost all the leaves down in one go. That made the rails very slippery, resulting in trains skidding and putting flat spots in the wheels.Replacing the wheels is not a simple job like changing the wheel on a car. The wheels are integral to the axle, so the whole body of the carriage has to be lifted with a crane so the bogie can be accessed. Remember there are 6 carriages on each train and total of 24 axles. Each axle and pair of wheels will weigh over half a tonne. It's a lot of work.To compound that, there won't be hundreds of spare axles with good wheels on hand. There might be enough for a few trains, but if you have 15 out of service, you will be waiting for axles to go off and be refurbished, even if you had the capacity in the depot to do the replacements.If you get a major incident with lots of trains getting wheel flats, it can take months to recover. At the end of the very hot summer in 2003, the temperature dropped by about 10 degrees overnight. The grease in the track lubricators, which had been set for the hot weather, got a lot thicker and built up on the rails. There were a lot of incidents of C Stock trains on the Hammersmith and City / Circle line skidding. One or two even skidded through platforms and couldn't stop. Trains were still being cancelled 4 months (or more) later as a result of all the wheel flats from that.They did go out and get some different grease after that incident where the viscosity was much more consistent at different temperatures.
Al Webber ● 27d