Definition: Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.
Input: Over 6,000 navvies were hired for up to two years building, blasting and clearing rubble beneath the South Downs to create Clayton Tunnel.

Over 6,000 ships were hired for up to two years of building, blasting and clearing rubble beneath the South Downs to create the Clayton Tunnel.