Emergency services were called shortly after 1.30pm on Monday, January 31 to the junction of Guildford Road and Merryfield Drive in the town.
A man in his 70’s suffered serious injuries and sadly died at the scene. His next of kin have been informed.
Road closures remain in place in the area while the incident is investigated.
Officers investigating have asked anyone who witnessed the collision or anyone with relevant dashcam or phone footage to email information to: collision.appeal@sussex.police.uk or call 101 and quote Operation Sutcombe.