As countries loosen lockdown restrictions, one key to getting life and the economy back up and running is how to be sure people can (safely) get around.

Cities in particular face the tricky puzzle of public transportation in the face of the acutely contagious nature of COVID-19. How can people respect social distancing inside packed buses and subways? But as the clamor to restart shutdown economies grows louder, countries and cities are busy implementing new rules. Here is how four major cities around the world are adapting public transports:

• Milan: The capacity of the Italian city's subway will be reduced by up to 30%, carrying just around 350,000 passengers a day instead of 1.3 million, reports Corriere della Sera. The access to train and metro stations will also be controlled and limited from May 4, when the lockdown starts to loosen. The city is also testing solutions to help people respecting social distancing, like putting red stickers on the floor to tell them how far apart to stand. Many seats will be removed as well, which will divide by two the numbers of passengers in the same car.

• Paris: France recently unveiled its plans to gradually end the lockdown beginning May 11, including new rules for the RATP, the state-owned public transport operator in the region of Paris and its daily 12 million travelers. Like in Milan, the use of face masks will be compulsory and markings on the ground will be used to make passengers respect safety distances. But contrary to the Italian city, traffic will increase. For Prime Minister Edouard Philippe public transport is a "key measure for the economic recovery" and therefore, he required the RATP to increase traffic to 70%, as it had been functioning at only 30% of its capacity in March and April, according to Le Parisien.

A staff member disinfecting a subway train carriage in Beijing — Photo: Chen Zeguo/Xinhua/ZUMA

• Beijing: Beijing metro was one of the firsts to test high-resolution sensing cameras which can identify whether passengers are wearing masks. Now the Chinese capital is lowering its restrictions from the top level to the second level starting April 30 and is going to increase traffic in public transportation. According to Xinhua, the maximum allowable passenger capacity will be raised from 50% of full capacity to 75% on buses and to 65% on subway trains. However, the buses and subway carriages will still need to be disinfected and ventilated regularly and all passengers will be required to wear masks and have their temperatures taken. Eating in public transport has also been banned, as Beijing has implemented a new set of regulations to promote "civilized behaviour" and improve public hygiene.

• Tehran: As the Iranian capital increasingly returns to work, the head Tehran's anti-coronavirus task force, Alireza Zaali, estimated that 570,000 people using public transport each day, ILNA reported. But in a separate report, the agency cited Zaali as saying that only half of metro passengers are currently using masks and gloves. The city council is debating the "mechanics' of enforcing the obligatory use of face masks, the daily Hamshahri reported. Some have suggested the government sell cheap masks to transport users at metro stations and bus terminals.