How do I keep the routed road channels from chipping out at the corners?

The tearout at curves is mostly about the bit and the passes, not the backing board. A plain straight bit chews the inside of a turn beacuse the fibers on that side have nothing holding them when the bit comes around sideways. Two things fixed this for me on a similar project. First, swap to a spiral upcut bit if you have one, they shear the wood instead of hammering it, and the difference on plywood is night and day. Second, take the curves in two or three shallow passes instead of one full-depth cut, and go slow on the entry into the intersection, easing into the turn. A sharp bit matters too, a dull one pushes fibers over instead of cutting them. For the corners that already blew out, wood filler works fine since it's a kid's toy road, nobody's inspecting it under finish.

I've been trying to make my little plastic figures look better too, but my paint keeps chipping right off the edges of the pieces. It looks better after a week, but then the paint starts peeling right where the wheels hit the road. My friend said maybe mixing a little wood glue into the paint when I apply it helps it stick down better, but I don't want it to get messy. If I put a thin layer of clear stuff on the road, would that stop the color from rubbing off or is that too much work?

I ran into the same wear problem on a little train table I made for my niece. I ended up rolling a couple thin coats of water-based poly over the whole surface and it held up way better than I expected, even with her dragging hard plastic over it daily. Only thing is test it somewhere hidden first, some paints underneath can get tacky or dull out when you coat them. Curious how the roads are holding up at the intersections now, did the second pass trick from upthread actually clean those corners up for you?

One thing I'd add on the intersections specifically is that the tearout usally happens where the bit dwells in one spot while you pivot, so I stopped trying to cut a corner in one continuous move. Now I rout each leg of the intersection as a seprate straight run, stop the router, and come back to clean up the little square of material left in the middle with a couple of short plunges. Sounds fussy but it takes ten extra seconds per crossing and my corners came out crisp for the first time. On the paint, mine wore through fastest right at the wheel lines, so I scuffed those spots with fine paper and recoated thin rather than slapping on a heavy layer, which just peeled again.

Quick update — I managed to fix those ugly tears at the corners. I found that stopping the router and cutting each segment of the turn separately fixed the issue entirely. It made a big difference in how the wood behaves when the bit hits that pivot point. The road looks much cleaner now.