Body damage was the main enemy of the No. 4 EBT cars. They were well built, but operate in an area exposed to salt air and droppings from both sea birds and jet aircraft, which use a runway which lines up with Orient Heights Yard. The Cor-ten steel is good, but is welded with carbon steel in places. This allows oxidation to attack from within, creating the type of rust bubbles often seen on these cars. There is less on the Orange Line cars which have no roof attachments to speak of, but they can appear at any weld.
Since the Orange Line cars are less exposed, they have fewer problems. They were also the last cars for Boston to use traditionsl GE control systems, which are becoming difficult to locate parts for. I am sure the remaining No. 4 cars will be picked clean to keep the Orange Line cars going a few more years. The two cars going to Broadway Upper will never run again, and Seashore's pair will rust away ...
Gerry. STM/BSRA
The next stop is Washington. Change for Forest Hills Trains on the Winter St. Platform, and Everett Trains on the Summer St. Platform. This is an Ashmont train, change for Braintree at Columbia.