Rail yards are starting to rumble with activity again as freight railroads invest in expanding capacity and improving service. The Wall Street Journal reports that Norfolk Southern and Union Pacific have recently reopened several “hump yards,” where trains are broken down and reassembled for their next destinations.

The yards were among operations that had been significantly curtailed in the industry’s years-long push to operate more efficiently by using fewer trains and holding them to tighter schedules.

The cost-cutting shutdowns helped boost profits, but shippers say they have paid the price through service disruptions and delayed shipments. Norfolk Southern says it has improved dwell time for its cars since reactivating a yard in Bellevue, Ohio.

Shippers say they see the railroads’ efforts to improve service, but added that they are still dealing with delays and have to use pricier truck transport more than they would prefer.