FRA is proposing to amend certain regulations governing positive train control PTC systems. Since December 31 2020 by law PTC systems have generally governed rail operations on PTC-mandated main lines which encompass nearly 59000 route miles today. Through FRA's oversight and continued engagement with the industry FRA has found that its existing PTC regulations do not adequately address temporary situations during which PTC technology is not enabled including after certain initialization failures or in cases where a PTC system needs to be temporarily disabled to facilitate repair maintenance infrastructure upgrades or capital projects. FRA expects PTC systems to be reliable and robust further reducing the occurrence of initialization failures and outages. This NPRM proposes to establish strict parameters and operating restrictions under which railroads may continue to operate safely in certain necessary scenarios when PTC technology is temporarily not governing rail operations. The purpose of this NPRM is to enable continued safe operations and improve rail safety by facilitating prompt repairs upgrades and restoration of PTC system service.