Essential upgrades were completed on the Norwich to London rail line over the bank holiday.
The upgrades were part of a £250m programme to upgrade the overhead wiring system to provide a more reliable service for passengers.
This new wiring system will also allow Greater Anglia to run their fleet of new trains from 2019 and allow more trains to run in the future to meet growing passenger demand
The wiring system currently in place is one of the oldest in the country.
The new system adapts automatically to heat during the summer, meaning fewer delays and cancellations caused by wires sagging in hot weather.
Jamie Burles, Greater Anglia managing director, said: 'These engineering works are vital to the transformation of the railway in East Anglia so that passengers can enjoy the full benefits of new trains running on more reliable infrastructure.
'We had just under 240 rail replacement buses and extra staff on hand to make sure people could complete their journeys as easily as possible.'
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