1. The Alaska state government has proposed to construct a railroad, which will link the rail networks of the US, Canada and Russia via a 90km rail tunnel beneath the Bering Straits - Власти Аляски предложили построить железную дорогу, которая соединит системы ж/д США, Канады и России через 90км-вый тоннель под Беринговым проливом. - has proposed (present perfect active) to propose - will link (simple future active) to link
2. The underground railway is the quickest, safest, most reliable and comfortable means of public transport, which is currently operating in 80 cities all over the world. - Подземная железная дорога - это самый быстрый, надежный и удобный вид общественного транспорта, который существует в 80 странах мира. - to be (is) (Present simple active) - is operating (Continuous present active) to operate
3. Sleeping cars were being used on American railroads since the 1830s; however, early sleepers were very uncomfortable for traveling over long distances. - Cпальные вагоны используются на железных дорогах США с 1830-ых годов; однако, первые вагоны были неудобны для долгих путешествий. - were being used (past continuous passive) to use - were (simple past active) to be
4. It has been calculated that East Japan Railway Company sells 1,000 tons of tickets annually. These tickets are now being collected and re-used in the manufacture of cardboard and toilet paper. - Подсчитано, что Восточная японская железнодорожная компания продает 1000 тонн билетов каждый год. Эти билеты собираются и используются повторно в производстве картона и туалетки. - has been calculated (present perfect passive) to calculate - sells (simple present active) to sell - are being collected (present continuous passive) to collect - are being reused (present continuous passive) to re-use