Visit from a London Underground worker

Mr Bark came to visit us and told us all about keeping safe as a London Underground worker. We found out lots of facts about the underground system. How many facts can you remember? 

• Only half of the train tracks are actually underground. The rest are above ground.
• The shortest escalator is only as tall as a giraffe!
• If we add up all the journeys that ALL the trains make each year we could fly to the moon and back 90 times.
• There are half a million mice living on the tracks near the platforms. 
• The longest track is 17 miles. 
• Workers wear quick release jackets with poppers which will come off  immediately if their clothing becomes caught in a train. 

Then we tried on some of his safety clothing. It was very bright and very strong. Can you explain why?