It's both reasons alluded to above, plus one.
Laws of physics, the white roof won't absorb sun/heat like a dark one, even aircon-fitted trains would thank you for that.
Physical access above the cantrail line brings safety challenges and obligations, and costs time.
And yes, less vinyl used means lower cost and slightly quicker fitment.
I think they look great, the white roof isn't incongruous like I had initially feared.
Laws of physics, the white roof won't absorb sun/heat like a dark one, even aircon-fitted trains would thank you for that.
Physical access above the cantrail line brings safety challenges and obligations, and costs time.
And yes, less vinyl used means lower cost and slightly quicker fitment.
I think they look great, the white roof isn't incongruous like I had initially feared.