Overnight test runs between Norwich, Diss and Great Yarmouth are set to be carried out by two of Greater Anglia's new trains.
Road-users are warned to remain vigilant at level crossings where they not used to trains operating in the early hours in the next couple of weeks as the tests get underway take place.
Initial testing is taking place over night so that it does not clash with passenger services.
The 'bi-mode' trains, which switch between diesel and electric power, will travel between Diss and Norwich and Norwich and Great Yarmouth on various nights over the next fortnight, between 11.59pm and 5am.
Ian McConnell, Greater Anglia franchising and programmes director said: 'It's very exciting to have some of our new trains on our network now, but we are warning motorists, cyclists and pedestrians in Norfolk to watch out for level crossings in use at times when they're not used to trains being in service.
'There are a number of safety, performance and familiarisation tests we need to complete on our new trains before they come into service later this year.'
Test runs between Norwich and Diss will check the mechanical working of the train's pantograph - the device which picks up electricity from the overhead line – which raises and lowers as it switches from diesel to electric power.
At this stage, the pantograph will not be taking any power from the overhead line, the test is just to check the working of the machinery on top of the train.
On test runs between Norwich and Great Yarmouth, technicians will be checking the train's automatic selective door operation, which ultimately will be used if the train is longer than the platform it is calling at.
This is used on some of Greater Anglia's existing services when they call at small stations such as Kennett, near Bury St Edmunds.
The tests are the latest stage of a £1.4bn investment that will see all of Greater Anglia's diesel trains, which run on regional routes, including between Norwich and Sheringham, Great Yarmouth and Lowestoft, replaced with 169 brand new trains.
The new trains, made by Swiss manufacturer Stadler, will all be longer, with more seats, free fast WIFI, plug and USB points, air conditioning, wheelchair spaces and accessible toilets.
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