Railtrack failed because it was a flawed idea from the start. In fact the entire privatisation model was flawed. The greatest period in Britain's railways was between 1923 (when dozens of small railway companies were merged into "The Big Four") and the outbreak of WW2. During that period, each of the four companies (London Midland & Scottish Railway, London & North Eastern Railway, Southern Railway and the Great Western Railway) were responsible for their operations in their entirety. They built and maintained their locomotives and rolling stock, laid and maintained the track, provided the signalling and station staff as well as the train crews and all the ancillary staff. This was the perfect model for privatisation and the railways flourished during that period. This was the time of luxury high speed expresses, streamlined locomotives, the "Race to the North" and the time when LNER's "Mallard" locomotive set the world record speed for steam traction, which still stands today. Unfortunately WW2 left the railways in a terrible state, having for six years been ravaged by the war and the demands wartime operations placed upon them.
This is how the railways should have been re-privatised in the 1990s. Unfortunately EU directive 91/440 put paid to that. This called for member states to arrange their railways so that infrastructure management and train operations should at the very least be financially separated, though it recommended that members should go further than that by completely separating train operations from infrastructure. Hence was born the TOCs (Train Operating Companies), the ROSCos (Rolling Stock Companies) and Railtrack (alongside the huge administrative industry required to keep track of the interactions and payments between these three entities). Alas Railtrack was doomed to fail from its birth.
So far as rail safety is concerned, two of the four most serious rail accidents (as far as deaths and injuries were concerned) since WW2 involved infrastructure failures. In 1967, 49 people died and 78 were seriously injured when a train derailed at Hither Green. The cause was a broken rail. In 1988, 35 people were killed and 69 seriously injured when two trains collided outside Clapham Junction. The cause of this tragedy was incorrect wiring made during a signal replacement. Both of these accidents, of course, took place under a nationalised railway regime. Since privatisation there have been only two accidents where the death toll reached double figures. These were at Ladbroke Grove in 1999 where a collision saw 31 deaths when one of the train drivers passed a signal at danger. Then in 2001 at Great Heck in Yorkshire, 10 people died when the driver of a Land Rover fell asleep and ran down an embankment onto the track where it was hit by passenger train and a freight train.