This poster is on the Department Of Transportation’s (DOT) demonstration of backup and complementary technologies to the Global Positioning System (GPS), to support positioning, navigation, and timing (PNT) applications. NextNav was included in the demonstrations planned to be conducted at the NASA Langley Research Center in the Spring of 2020, for technologies capable of providing backup PNT services to critical infrastructure in the event of temporary disruptions to GPS. NextNav is contributing both equipment and engineering services for the planned demonstration at the NASA Langley campus. This poster discusses NextNav’s Metropolitan Beacon System (MBS), a standalone terrestrial network that delivers the backup PNT services sought by DOT, as well as some demonstration results and/or lessons learned from NextNav’s participation in the DOT demonstration.