Goalposts are going to be needed for just about any school or athletic field, even if the field is only used for team practice. You cannot properly train a team if they cannot use the same equipment they will use during play, and this includes posts and markers. If you're responsible for providing equipment for any school or other facility's field and need to replace or purchase new goalposts, note a few things to consider so you're sure you get the right choice.
AFL, NFL, and other sports
Keep in mind that many teams and competitions today are widening out their area of play, and especially in schools. It's not unusual to see American NFL football being played in Australian schools, while Australian soccer and rugby both are also becoming very popular in the United States.
When choosing goalposts, opt for those that are interchangeable between as many sports as possible so you can accommodate this variety; this might include a crossbar for the NFL uprights and a net for soccer, as well as the staggered sizes needed for AFL games. You may even want posts with drilled holes at certain levels that accommodate a basketball backboard and net.
Lightweight aluminium can be very durable, but when choosing goalposts for AFL or soccer in particular, keep in mind that this might mean an added risk of a player running into the goalposts, not something that often happens with NFL games. PVC can be a better and safer option especially for schools, where inexperienced players may forget to watch for the posts and nets. The softer plastic of the PVC may absorb more impact from a player, reducing their risk of injury.
Backyard versus professional
Be very cautious about opting for what are called backyard posts, as these are exactly as they sound; lightweight posts that are used by casual players. They may be set up in a city park or other area that doesn't see regular play, but they may not be durable enough to withstand constant use in a school or a field for a professional team. Lightweight backyard posts may also have very poor-quality connectors that are meant for easily disassembling the posts when they need to be stored. These connectors might cause some swaying when the posts are assembled. For a school or professional facility, always opt for professional quality goalposts so you know they'll be rugged enough to last for years.
For more information, talk to a professional like Adda Flagpoles Pty Ltd.