We upgraded the Central line in the 1990s. It was the first line to get a complete overhaul - with new trains and new signalling.
The upgrade allowed us to increase capacity by adding additional trains, especially during peak periods. We now run 30 Central line trains an hour in peak periods, or one every two minutes.
The trains are also operated automatically which, together with new signalling, means they run more quickly and the journeys are smoother.
More comfortable and reliable trains
It's now time for a makeover. So we're refreshing the entire fleet of 85 trains, so you can look forward to a more comfortable journey in brighter surroundings.
As seats on the Underground normally only last around seven years, we plan to replace all seat backs and pads across the line's 25,000 seats and sitting perches.
These new seats will not only be more comfortable, they will also look good as we're covering them with a new fabric that will be used across all Tube lines in future.
Work has also begun on replacing train windows. At the moment, they take eight hours to replace and require testing every 90 days. As our new windows are bolted, not bonded, into place, they only take an hour to change and it also reduces the risk of them coming loose or letting in rain water.
While we're carrying out this work, we plan to replace around 250 body panels at the end of carriages. Together with new windows and seats, this will give a fresh, new look to trains across the line.
We're refreshing two trains every week, and it's all planned very carefully to ensure there is no disruption to your service as a result of this work.
At peak times, Bank is one of the most congested stations on the Underground. It's also a complex one as it's interlinked with nearby Monument.
To help remove some of the bottlenecks, we're refurbishing or replacing all of its 15 escalators. We'll also be introducing a one-way system in parts of the station, which should help ease congestion while the work's being done.
We aim to keep Bank open throughout the works, but it's a big, complex project, so please bear with us.
You may have noticed that work has started on the upgrade of Bond Street station. It's a key West End station that will become even more important when Crossrail arrives - with 24 trains an hour in both directions at peak times.
Right now, a lot of preparation is going on as we get ready to upgrade the station, and sometimes this may lead to changes that'll affect your journey.
We know it's disruptive but it'll be worth it because by the time it's complete in 2017, the station will have a bigger ticket hall, step-free access from street to platform, and extra escalators to get you moving more quickly.
If you've visited Tottenham Court Road lately, you may have noticed that one of the Central line's busiest stations is being re-built. It's a really exciting project that'll change the way the station and the area around it is used.
By the time it's complete in 2016, the station will have a new ticket hall, step-free access to the platforms, and a pedestrianised plaza outside the station.
It will also be an interchange station for Crossrail, with 24 trains an hour expected to pass through the station each way during peak periods.
There's a lot of work to be done, so please bear with us. We'll try to keep disruptions to a minimum.