Commuters in Barcelona were expecting delays on Tuesday as metro workers called a two day strike that is set to hit travellers particularly hard during rush hour.
Only 50 percent of trains will be running during rush hour in the city - from 8am to 10am and from 5.45pm to 8pm and 30 percent of trains will be running between 8pm and 9pm.
The strike comes at a particularly awkward time; the city is currently playing host to the Alimentaria food trade fair - many attendees could be affected by the transport strike.
Fira de Barcelona, where the trade fair is taking place, is running extra buses from the city's main hotels and has made available more parking spaces for people attending the fair.
Metro workers staged a similar strike during February's Mobile World Congress trade fair, which took place in the city.
Metropolitan Transport Barcelona (TMB) has advised people to take alternative modes of transport if necessary.
Workers will strike on Tuesday and Wednesday, when transport officials estimate that only one in three trains will be running for much of the day.
TMB has also announced that the strike could affect the Montjuïc cable car, a popular tourist attraction that is run by the city's metro.