The Tube has about 400 kilometres of tracks.

It has 276 stations. It carries more than 1 billion people a year.

Tunnelling underground

The idea of an underground railway in London was first brought up in the 1830s. There were many problems.

First, it was hard to find money for the project. The other problem was making the tunnels.

Today we have machines that can tunnel underground. In the 1860s, when work began, people had to dig a long hole and then cover it over.

When the first Underground line opened in 1863, the trains were steam trains. This added another problem. Openings - or vents - were needed on the surface to let out all the steam.

By 1900, the old steam trains were replaced by electric trains.

By this time, tunnelling had also become much more advanced. It became possible to make deeper and longer tunnels.

Mapping the Tube

In the beginning, the Tube was not very convenient. Passengers had to walk a long way to change lines. And as the network grew, it became confusing. The Underground needed a good map.

The first map came out in 1908. It had eight different coloured lines.

It was very confusing in the parts of London where there were many lines and stations.

In 1933, a man called Harry Beck came up with a solution. He based his map on a map for underground sewage systems. It showed how to get to a station and where to change.

It is considered a design classic. All subway system maps are now based on his design.

Flooding and ventilation

The London Underground is an amazing engineering success. But it still has problems.

Every day, tonnes of river water has to be pumped out. In the past, people worried it could one day be completely flooded if the Thames overflowed. In 1986, a flood barrier was built.

Ventilation is also a problem. In the summer, it can become dangerously hot. In 2001, some stations pumped a fragrance into the air. It was stopped after one day because it made some people unwell.

now do this

1 The London Underground is the longest city rail network in the world with ...

a. 276 kilometres of tracks

b. 400 kilometres of tracks

c. 1,000 kilometres of tracks

2 The Tube's classic map design came out in ...

a. 1933

b. 1908

c. 1863

3 The summer heat in the London Underground is a problem of ...

a. ventilation

b. engineering

c. flooding

Answers

November 18

1. b, 2. c, 3. a