A civil engineer must be able to design safe structures which meet standard codes in the regions that they are being built in. These structures must be designed with maintenance, efficiency, and other economic concerns in mind as well to ensure that they will endure through years of use.
In terms of transportation, civil engineers build bridges, tunnels, freeway interchanges, and other structures which are designed to facilitate the smooth, even flow of traffic while allowing for expansion and higher use rates. Water treatment includes sewage plants, delivery systems for fresh water, dams, and other facilities which handle both fresh and waste water, while government buildings run the gamut from police stations to city halls. A civil engineer might also work on projects like a city power plant or a major office building.
Pay for civil engineers tend to be reasonably high, considering that these professionals are highly trained and very skilled. Jobs in public service may not command as much pay, but they may come with benefits and prominent positions in the community, while private contractors can woo civil engineers with very attractive benefits and compensation packages. The position can also be dangerous, depending on how much time a civil engineer spends in the field, but it can also be very exciting, especially in regions which are integrating cutting edge technology and design techniques into their public works.