With no explanation, label each line with "O", "location-road/railway/highway/transit", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
The
line
was
doubled
in
1874
when
the
Clifton
Extension
Railway
opened
,
then
expanded
to
four
tracks
and
platforms
in
1888
.
The:O
line:O
was:O
doubled:O
in:O
1874:O
when:O
the:O
Clifton:location-road/railway/highway/transit
Extension:location-road/railway/highway/transit
Railway:location-road/railway/highway/transit
opened:O
,:O
then:O
expanded:O
to:O
four:O
tracks:O
and:O
platforms:O
in:O
1888:O
.:O