T officials explained state of good repair using as an example a car with an expected useful life of eight years. The officials said maintenance costs during the car’s first two years on the road are minimal but start increasing in year three through eight. Beyond year eight, the vehicle may continue to run well but the odds are that maintenance and repair costs will start rising to a point where the vehicle should be replaced.

Ronnie Valdivia, the MBTA’s director of asset management, said the car example illustrates the challenges of managing assets, deciding when it’s time to replace rather than repair.