They are gaining capacity. The existing checkpoints cannot expand. Because each one only accesses one pier, they also cannot balance loads if there's a backup at one pier but no line at another. With DCA's passenger numbers rising, they need the additional capacity.

The other big reason AA is willing to foot the bill for this via higher fees they'll pay is because they'll now have their operation spread over three piers (two existing and one new pier), and the existing shuttle bus transfer operation is wholly inadequate for that.

MWAA also expects the retail, once behind security, to do much better. I don't think they get much business from unticketed passengers as it is. I do expect the retail mix will change a bit, with sit down restaurants behind security, there will be a chance for new opportunities.

Plus, the space now occupied by the security checkpoints will be a good opportunity for retail.