How can I keep cats away from garden wall

[ironmanslady]

Our garden is behind a main road and there's a wall, lots of trees/hedges and then the road. Recently the council have cut the trees back and shut the road a little further along for major road works. Trouble is now the road is quiet, still used but a lot less traffic, my own cat plus all the neighbourhood ones are on my wall chasing birds. This isn't a problem but one went over and sadly got hit by a car at speed and it was horrible. I don't want this to happen again and I'm constantly out trying to get them down without scaring them and them jumping over. It's becoming a nightmare. What can I put on the wall to stop them going up there, it's never been a problem until recently with it being quieter as the constant stream of cars used to scare them enough not to venture over.

[RubbishMantra]

Could you put a trellis up, that won't bear their weight?

Or something like this?

[RubbishMantra]

Also have a look at ProtectaPet. They'll install it, but if you're apt at DIY you can install it yourself, at a lesser cost.