>>1805635>but they're required to be 1/2 mile in lengthNah. The only limit is what the local authorities are willing to pay to upgrade to a QZ--the railroad doesn't cover the cost. Other crossings nearby get closed to save money when there's not enough to upgrade them all. For example, if there are two crossings near each other (presume no others nearby), then it doesn't make sense for only one of them to get the quiet zone treatment, because trains will still have to whistle for the other one. Often, the local authorities only have money to upgrade one, so the other gets closed during the process. Railroads like closing crossings as it means one less signal installation to maintain and less risk of a collision.
A city or county may be able to get the railroad to pay for some of the cost of a QZ if they agree to close nearby crossings permanently. That's all done on a case by case basis; some places dig in their heels and refuse to close crossings, others are perfectly willing to close them for upgrades to others.
