To my mind,computers are important in our life.A lot of schools buy computers,because it's necessary for pupils.for example,With computers they can use the internet and it's very comfortable and helpful even for teachers.Also pupils can write different articles and documents on the computers.
В Англии "подземный переход" называется subway. Я гарантирую это.
Железнодорожный: railway crossing, railroad crossing, road through railroad, train crossing, grade crossing, level crossing
Пешеходный: pedestrian crossing, crosswalk, а также zebra crossing, tiger crossing (в зависимости от цвета полосок)
"В трубе" - это скорее overhead walkway, или overhead crossing, или pedway или skyway
или (pedestrian) flyover в UK и overpass в US