MBTA OFFICIALS ON MONDAY said they are taking a number of steps to reduce Green Line derailments, of which there have been 10 since the beginning of 2015.

Jeff Gonneville, the chief operating office of the T, said five of the derailments were caused by a combination of track conditions and the operator driving too fast. Four other incidents were caused by other factors, such as a buildup of snow and ice on the track, human error, or a vehicle or switch defect. One derailment that occurred earlier this month at Copley Station remains under investigation.

The high incidence of derailments was first reported last week by the Boston Globe, which said the T had the highest number of light rail line accidents in the country in 2015. The Globe said there were seven derailments in 2015 and five so far this year.

Gonneville’s presentation to the T’s Fiscal Management Control Board indicated there were five derailments last year and five this year. Using the measuring stick of light rail derailments per 1 million train revenue miles, Gonneville said the T did not record the highest number of derailments in 2015 or 2016.

According to Gonneville, all but three of the Green Line trains that derailed were so-called Type 8 vehicles that entered service in 1999 and have a long history of derailment problems. The T addressed the problem many years ago by grinding down the wheels on the trains and the rails to create a better alignment. The T also mandated that the vehicles travel at much lower speeds. The problem abated for many years, but returned with a vengeance in 2015.

Gonneville said the T is planning to grind down the rails for the first time in nine years and is also taking a number of steps to better monitor tracks, train wheels, and driver speed. Officials are even installing a lubrication system that will avoid the type of friction between train wheels and track that can lead to derailments.