How do I stop my player falling through my physics bridge

I made the physics bridge using round logs and distance joints. But my player falls through it. I have the physics behaviour on the player but he still sort of slips between the joints, even when i place the bridge peices right up against each other. Its baffling my brain.

Thanks

You could add an invisible solid object behind the bridge for the player to walk on...

That worked in general but its still not perfect, ill fiddle with the settings and see what i get. Thanks for the advice.