The Larne-bound platform at Whitehead station the day after the collapse:
And after the debris was cleared away:

Contrast this with the ordered but very lengthy (around 6 months) rebuilding of the platforms at Deptford Bridge DLR station to allow 3-car trains to run. This photo taken last Sunday shows the finished result - still closed off to passengers but bizarrely displaying an information board which includes out of date Christmas and New Year service information...
Nowadays of course many metro systems use platform edge doors, the Jubilee Line being one example. Even these do not provide absolute safety as this incident in Shanghai demonstrated.