The railway here was opened in 1854 by the St Helens Canal and Railway Company and was later absorbed by the London and North Western Railway. It is still in use for regular freight trains although the passenger service ended in the early 1960s. The attention of the weed killer train is evidently needed.
Thanks to Steve Parish for providing more information about The Eye...
Apparently, the mural was painted by a local man, Anthony Turk, who is a painter and decorator by trade. He originally intended to create an under water scene but planners knocked back this idea on the grounds that it would distract drivers.
Also, please check out this archived news item here