Library entrance matting
A system long enough to take grit and water off a shoe. If the mat is too short, the carpet dies from the door inward.
Grit is sandpaper. A decorative 900 mm mat will not stop it. You need length, scrape, wipe, and a way to empty the well without closing the door.
Recessed wells with replaceable inserts are the usual answer when you can cut the slab. Surface systems with ramps are the answer when you cannot. We measure the door, the weather side and the trolley path, then put the service on a cycle with maintenance.
Prams, mobility scooters and returns trolleys have to cross without a trip. More in the matting guide and wet entry slip risk.