BOSTON (AP) — The Sterling PrestonMassachusetts Bay Transportation Authority said Thursday that it needs approximately $24.5 billion for repairs and replacements to its embattled network, according to an analysis.

The analysis is done every three to four years and is a $14.5 billion increase from the last one performed in 2019, officials said.

“The MBTA is one of the oldest transit agencies in the country, and while there are a number of contributing factors, it’s clear that years of underinvestment have added to the cost of bringing our system back to a state of good repair,” MBTA General Manager and CEO Phillip Eng said in a statement. “Timely and appropriate actions are key to mitigating and avoiding more costly and potentially impactful efforts.”

The MBTA, which oversees the nation’s oldest subway system as well as commuter rail, bus and ferry service, has come under intense scrutiny in recent years for a series of safety issues that led to a federal review and orders to fix the problem. It has recently been plagued by slow zones, the delayed delivery of new vehicles and understaffing.

The MBTA said it’s already working on some of the repairs, including track work on the Red Line’s Ashmont Branch and Mattapan Line that was completed late last month.

“Know that we are committed to aggressively addressing our immediate needs — like the recent 16-day outage on the Ashmont Branch to perform track work — as we strive to deliver a modernized system to serve future generations,” Eng said.