To many, a traffic signal isn’t more than just an everyday object.But for Solon, the installation of its first-ever traffic signal, at Highway 1 and Main Street, last month is a bellwether of its immense growth.Solon’s business and population growth rate increase — to which Mayor Steve Stange has had a front-row seat, growing up on Main Street — is matched by its small town counterpart of Tiffin.While still small Johnson County towns, both have seen new businesses spring up as their populations spiked more than 115 percent since the 2000 census.