I'm also getting this error. I have 9 tiles in play and a large, but not overly excessive road network and I've apparently maxed out my lane count. I cannot build any more roads and my city is really not that large.

Possibly the lane customization is consuming additional lane count? Anyway, I can't really fault the mod.

Edit: Grab the "Phantom Lane Remover" mod. It seems Traffic++ creates these extra lanes and this will push you to the object limit. The mod will allow you to detect and clean up these extra lanes.

I removed over 230k phantom lanes and saved my city as a result.

Thank you Vigilante! I have searched everywhere but would have never thought to search for that mod. You have saved my game! I can play again.

Yes, I just discovered this mod, and it cleaned up and completely fixed my city. This should help the traffic++ dev to figure out if it is indeed traffic ++ doing the damage by not cleaning up properly.

http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=536250255&searchtext=phantom