Businesses in Wales need to be ready to make the most of investment in major construction projects like the £1.1bn electrification of the main London to south Wales railway line, say experts.
That includes ensuring people have the right skills and that firms are in a position to bid for contracts.
"Businesses need to make sure they are positioned to take advantage," said Emma Watkins, director of CBI Wales.
The line to Cardiff and Swansea should be electrified by 2018.
A further programme for the south Wales valleys lines is scheduled to follow.
Once the new electric trains are operating between Cardiff and London in 2017 it will cut journey times by around 20 minutes.
Electrification is just one of a number of proposed construction projects that will require skilled workers including the M4 relief road, the Hinkley Point and Wylfa Newydd nuclear power plants and the Swansea Bay Tidal Lagoon.
Colleges, training providers and companies are already working together ahead of electrification.
But a plan needs to be put in place to ensure that enough skilled workers from Wales are available for all of the projects that go ahead, according to Wyn Prichard, the director of construction skills and strategy at Neath Port Talbot College.
"The dangers really for Wales are we miss out on opportunities for local people and (for) those skills to be developed at apprentice and graduate level," he said.
"There is an opportunity, given this investment, that Wales could lead the way in certain qualifications as it has done before."
Ms Watkins said Wales was sitting "on the verge" of a number of large scale projects which could boost local businesses if they and their employees were ready to take the opportunities ahead.
Apprentices in south Wales are getting hands-on experience of railway work without having to see a train.
A special track, the first of its kind in Wales, has been built at Coleg y Cymoedd at Nantgarw, Rhondda Cynon Taff, so apprentices can be trained to work on the huge project.
Health and safety and teamwork is key.
As well as electrification, Network Rail are looking ahead to the next 30 years and in a study last month forecast rail travel into Cardiff will grow by 20 million passengers by 2043.
source: BBC