The roots will not grow across the sidewalk, however they are shallow and will be partially exposed as the tree matures. Also these trees need moist soils during establishment so you will need to irrigate it when it gets dry. They also produce small pods so if you are anal about stuff like that, it can be an issue. Tree guru loves this tree and says it makes a great street tree. I suggest you visit one of the botanical gardens in your area and check a mature tree out to better access it. Best And Happy Yardening, Nancy.