The Flying Scotsman is due to embark on its second visit to Scotland since its restoration in February last year.
About 800 passengers are due to take two trips on the iconic steam locomotive, which will depart Edinburgh Waverley on Sunday at about 11:00.
The engine will travel over the Forth Bridge before taking a tour of the Fife coastline and returning to Edinburgh.
A second trip across the Forth is also planned for later in the day, when the engine will also visit Forth Valley.
Police and transport officials have warned that drone use is not permitted within 50m of the line and that onlookers should stay well away from the tracks.
The Flying Scotsman, which is based at the National Railway Museum in York, made its first post-restoration visit to Scotland a year ago.
Hundreds of enthusiasts lined the route and were later praised for their responsible behaviour.Image caption
However, the engine's inaugural run in northern England in February 2016 was marred when some fans put themselves in danger by encroaching on to the track.
Additional staff will be deployed at key stations and along the engine's route for the locomotive's latest visit to Scotland and the Network Rail helicopter will be scanning for trespassers.
Claire Newton, from the tour operators Steam Dreams, said it was difficult to give precise details of the engine's route, but said it would travel over the Forth Bridge three times on Sunday.Image copyright PA
She said: "For many people this is the trip of a lifetime and some have been on waiting lists for this trip since February 2016.
"We will be going over the Forth Bridge and travelling along the Fife coastline and then in the evening we will hopefully go past Stirling Castle before returning to Edinburgh."
The engine is on a three-night trip across Scotland until Monday.
The Flying Scotsman was the first steam engine officially authenticated at travelling at 100mph in November 1934 though it had been claimed that another engine, City of Truro, travelled at 102mph in 1904. There was no second timekeeper on the earlier run and the record has long been disputed.