Electricity from physical pressure?

A new experiment in France will use the pressure that is made by people walking on the street to electricity!
This Idea might also be used to create electricity from cars and trains movements.
This recycling idea is great, but some more experiments will have to be done to prove it's efficiency.
The estimation is that a system like that will be able to produce approximately 120 Kwh from trains traffic.
Lets hope it will work!