Railroad-giant Union Pacific said Thursday it will spend $24 million on rail projects in Arizona.

The purpose is to upgrade and improve safety on existing rail and bridges across the state.

Almost 90,000 railroad ties will be replaced on lines between Casa Grande and Nogales. Twenty-eight miles of rail line between Cochise and San Simon will get new concrete pads.

The company spent $221 million in Arizona rail maintenance from 2012 to 2016.