Cover your trampoline springs with pool noodles. I was pinched in springs so often when I was a kid. This is safe and looks awesome. Now I just need a house with a garden to put my pool-noodled trampoline in.
The city even has a tunnel for the cars to drive through, which is simply PVC pipe covered by mulch. Also, cement blocks painted and buried to create the roadway. (look out for spiders and snakes that may take up shelter in the pipe!