Playdate with friends

What a fabulous day we had. We invited a bunch of our friends out to the playground with us. I don't have pics of everyone but we had 10 moms and 20kids!!! It was such a wonderful start to hopefully a lot of nice weather this summer. My two ran almost non-stop the entire time we were there. And speaking about running, I am at a loss as to what to do with Sophia. She has gotten it into her head that darting into the road is a fun game. And I have NO IDEA how to stop this behavior. We have tried multiple time outs, we have actually left the playground/walk/our yard etc trying to punish her. Today she actually did this multiple times, to the point where the last while we were there I held her and wouldn't let her go, and she wasn't happy about it. But if you have any ideas on how to fix this let me know:-)