Traffic calming device

1. A traffic calming device comprising a moveable obstacle and a retraction mechanism for moving the obstacle when a vehicle is brought into contact with the obstacle, wherein the retraction mechanism comprises a release system for moving the obstacle at a predetermined speed,

wherein the predetermined speed is variable so that a user may set the predetermined speed in dependence on a speed limit,

wherein the obstacle comprises a cradle for engaging with one or more wheels of the vehicle, wherein the cradle is engaged with the retraction mechanism, the retraction mechanism comprising at least one hydraulic cylinder, the cradle being adapted for pivotal movement relative to a surface upon which the wheel proceeds, wherein the cradle is engaged with the at least one hydraulic cylinder so that the pivoting movement of the cradle commensurate with the forward direction of the vehicle compresses the at least one hydraulic cylinder, the release system further comprising a release valve engaged with the at least one hydraulic cylinder so that the at least one hydraulic cylinder has a maximum rate of operation, and so that the pivoting movement of the cradle is limited by the maximum rate of operation of the at least one hydraulic cylinder and

wherein the cradle includes first and second arms with a flat middle surface between the first and second arms.

2. The traffic calming device according to claim 1 wherein the obstacle is retractable.

3. The traffic calming device according to claim 1 wherein the retraction mechanism comprises a first and a second hydraulic cylinder, each hydraulic cylinder being connected to corresponding arms of the cradle so that pivoting of the cradle in a first direction engages the first hydraulic cylinder and pivoting of the cradle in a second direction engages the second hydraulic cylinder.

4. The traffic calming device according to claim 1 wherein the retraction mechanism comprises a fluid release.

5. The traffic calming device of claim 4 wherein the fluid release comprises an hydraulic piston.

6. The traffic calming device of claim 5 wherein the fluid release further comprises a release valve.

7. The traffic calming device according to claim 6 wherein a flow rate of the release valve is adjustable.

8. The traffic calming device according to claim 7 , wherein the predetermined speed is related to a fluid flow rate of said release valve.

9. A method for calming traffic including calming movement of a vehicle having wheels proceeding on a surface, the method comprising:

providing a moveable obstacle, the moveable obstacle being movable at a predetermined speed when the vehicle is brought into contact with the movable obstacle, the movable obstacle including a cradle having first and second arms with a flat middle surface between the first and second arms, the cradle being pivotably mounted relative to the surface, the cradle being adapted to engage with at least one wheel of the vehicle,

providing a retraction mechanism comprising at least one hydraulic cylinder for moving the obstacle when the vehicle is brought into contact with the obstacle, wherein the cradle is engaged with the at least one hydraulic cylinder so that a pivoting movement of the cradle commensurate with a forward movement of the vehicle compresses the hydraulic cylinder,

providing a release system including a release valve engaged with the hydraulic cylinder so that the at least one hydraulic cylinder has a maximum rate of operation, and so that the pivoting movement of the cradle is limited by the maximum rate of operation of the hydraulic cylinder,

setting a rate at which the release system will operate to set the predetermined speed, the predetermined speed being based upon a speed limit, and

moving the obstacle at the predetermined speed when the vehicle is brought into contact with the obstacle.

10. The method according to claim 9 wherein the obstacle is retractable.

11. The method of claim 9 wherein the obstacle is moved by a fluid release.

12. The method of claim 11 wherein the obstacle is moved by a hydraulic piston.

13. The method according to claim 12 wherein a flow rate of the release valve is adjustable.

14. The method according to claim 13 wherein the predetermined speed is related to a fluid flow rate of said release valve.

15. The method according to claim 9 comprising the further step of reversing a movement of the obstacle once the vehicle is out of contact with the obstacle.

16. The method according to claim 15 wherein the obstacle is moved back to an initial position.

17. The method according to claim 15 wherein the obstacle is moved back to a position varies from an initial position.