Basenjis are sighthounds…if they see it and want it, they chase it, no matter what. They are not impressed by roads and cars, hence the danger there. I would not recommend having a basenji off leash if there is any danger to them at all.
That said, I have trained most of mine over the years to come to a whistle (coach's type, as I can't whistle myself). It's pretty quick, I start in the house and blow the whistle and hand out a tiny very special treat. Repeat 5 or 6 times. Go for a walk in a safe place, blow the whistle and offer the treats a couple of times, then IN A SAFE PLACE ONLY take off the leash and in about 5 seconds blow the whistle while waving the treat toward them. Repeat every few minutes,along with lots of praise. After a few weeks, you don't have to treat each time, but do occasionally so they always want to come. Mine would turn on a dime to return to me...unless there was a squirrel, or rabbit of more interest. We had the advantage of finding a huge fenced area where I could take them back before there were dog parks. Now we go to safe parks, and I can't take treats into the park, so they are not as well trained and don't come immediately.
I think this is excellent training for a puppy, though they may not train as easily as an older dog, with that 2-second attention span a pup has. But the earlier you can imprint something like whistle=come to me and get a treat, the more likely you are to get them to come to you when (not if) they escape.
Anne in Tampa
I still keep a whistle by the front door, in case of an escape.