Passengers are being warned to expect disruption to trains running through Derby, in the biggest upgrade to its railway in decades.
As part of the £200 million project, 17 kilometres of track will be replaced, new signals will be installed and a new platform will be built at the station.
Work began on Sunday and will continue for 79 days, until Sunday 7 October.
Rail operators hope the investment will improve the performance and punctuality of trains to and from Derby station.
While the work is carried out, there are changes to timetables, including replacement bus services for some journeys.
Network Rail, East Midlands Trains and CrossCountry have set up a dedicated website, where people can check for changes to their journeys.
They are advising people to plan ahead and check for changes to services before they travel.
In some cases, passengers travelling on certain routes will be offered a discounted fare.
Here is how some of the main routes will be affected:
- Midland Main Line services
From 30 July to 7 October, there will be one direct train between Derby and London St Pancras, calling at Long Eaton, East Midlands Parkway, Loughborough and Leicester - except for 13 August, 19 August and 2 September.
Between 3 September and 7 October trains between Sheffield and London will be reduced to one per hour and they will not call at Derby. Replacement bus services are scheduled between Derby and East Midlands Parkway, where passengers can connect to London.
There will be no train services between Sheffield/Chesterfield and Derby between 30 July and 2 September - instead replacement buses will be used.
There will be no direct trains between Derby and London St Pancras between 13-19 August. Passengers will have to get a bus service to East Midlands Parkway, where they can connect to London.
Between 3 September and 7 October CrossCountry will operate one train per house between Sheffield/Chesterfield and Derby. There will be no rail replacement services.
- CrossCountry services
Services between Nottingham, Birmingham and Cardiff - and to/from the North East and Scotland - will not call at Derby, Spondon and Long Eaton until 2 September.
Rail replacement services will be in place for journeys to Chesterfield, Nottingham, Burton-on-Trent and the North East and Scotland.
From 3 September - 7 October, services will operate as normal with slight alterations. Journey times to/from the North East and Scotland will be increased by 30 minutes.
You can find more information on other train services to/from Derby on the dedicated website.