<Li> Replacement (upgrade) </Li> <Tr> <Th> Issues and ideas </Th> </Tr> <Tr> <Td> <Ul> <Li> Air traffic control </Li> <Li> Brownfield </Li> <Li> Carbon footprint </Li> <Li> Containerization </Li> <Li> Congestion pricing </Li> <Li> Ecotax </Li> <Li> Ethanol fuel </Li> <Li> Fuel tax </Li> <Li> Groundwater </Li> <Li> High - speed rail </Li> <Li> Hybrid vehicles </Li> <Li> Land - use planning </Li> <Li> Mobile data terminal </Li> <Li> Pork barrel </Li> <Li> Rapid bus transit </Li> <Li> Recycling </Li> <Li> Renewables </Li> <Li> Reverse osmosis </Li> <Li> Smart grid </Li> <Li> Smart growth </Li> <Li> Stormwater </Li> <Li> Urban sprawl </Li> <Li> Traffic congestion </Li> <Li> Transit - oriented development </Li> <Li> Vehicle efficiency </Li> <Li> Waste - to - energy </Li> <Li> Weatherization </Li> <Li> Wireless technology </Li> </Ul> </Td> </Tr> <Ul> <Li> Air traffic control </Li> <Li> Brownfield </Li> <Li> Carbon footprint </Li> <Li> Containerization </Li> <Li> Congestion pricing </Li> <Li> Ecotax </Li> <Li> Ethanol fuel </Li> <Li> Fuel tax </Li> <Li> Groundwater </Li> <Li> High - speed rail </Li> <Li> Hybrid vehicles </Li> <Li> Land - use planning </Li> <Li> Mobile data terminal </Li> <Li> Pork barrel </Li> <Li> Rapid bus transit </Li> <Li> Recycling </Li> <Li> Renewables </Li> <Li> Reverse osmosis </Li> <Li> Smart grid </Li> <Li> Smart growth </Li> <Li> Stormwater </Li> <Li> Urban sprawl </Li> <Li> Traffic congestion </Li> <Li> Transit - oriented development </Li> <Li> Vehicle efficiency </Li> <Li> Waste - to - energy </Li> <Li> Weatherization </Li> <Li> Wireless technology </Li> </Ul>

How do structures like roads and bridges serve as a foundation or framework for the nation