The man, whose age has not been given, fell from the Scarborough Road bridge over the A64 near Malton at 5.10pm. He was pronounced dead at the scene.
A number of witnesses spoke to police at the time but an appeal has now gone out for anyone with dashcam footage or who saw the incident to contact officers.
Drivers who were travelling in either direction at around 5pm are asked to come forward.
The road was closed until 1am on Sunday.
North Yorkshire Police said: "As you can imagine this has been an extremely upsetting incident for all involved and our thoughts are with the man’s family at this time.
"We also know the impact an incident of this nature can have on those who witnessed it or assisted in the aftermath. We would strongly encourage those people to speak with someone, and if needed, to seek advice from a professional - there are a list of agencies who may be able to help on our website.
"If you are able to help officers with their investigation, please provide reference NYP-15012022-0367 when providing information."