An 84-year old man was struck by a bus on Princes Street last Friday; the third pedestrian accident in the last fortnight.
Police said that he looked one way, but didn't check the opposite direction for diverted traffic.
Due to tram works, the street has been closed to one lane that allows both east and west-bound traffic.
The man was said to be in a serious but stable condition last week.
Inspector Jill Kerr, from the police's road policing unit said: "The man had been crossing from the northbound carriageway to the southbound.
"The bus was heading eastbound and it would look from our initial enquiries that he had only been looking to his left and had stepped out in front of the bus.
"The council are looking to put in extra lights and signage to try and make it even more obvious to look both ways."
A spokesperson for Lothian Buses said: "There's no confusion among bus drivers. They know the route they're following. I can only assume that people are used to doing things in certain ways and suddenly that's changed."
From 21 February, Princes Street will be entirely closed to traffic, which will be diverted along George Street and Queen Street. In addition, a replica tram will be stationed outside Jenners once the road closes. Council leader Jenny Dawe is encouraging residents to visit the full-sized model, which is set to arrive after the road closure.