Did he intend to push her to the ground and cause her injury, or did he intend to push her to her death in front of a bus he couldn't even see? Proving the latter beyond reasonable doubt would be next to impossible. I'd have thought Section 18 GBH would be more likely.
Not sure its just about intent. Perhaps it could be agrued that he acted in such a reckless manner that he should have realised that death or serious injury could result?