One such close call happened on Monday, when, according to an eyewitness, one of the driverless buses did not yield to a police car with its lights flashing when crossing the intersection at Mere Avenue, despite the Traffic Act requiring vehicles to yield in such situations.

As can be seen in photos, ERR photographer Rene Suurkaev also witnessed a situation in which one of the buses ignored a pedestrian green light and drove through the crosswalk, surprising pedestrians.

The intersection at Mere Avenue and Ahtri Street is the only point at which the driverless shuttle buses come in direct contact with live traffic, as the remainder of its route follows the tramway currently not in use due to track work further up the line. As this is the case, the driverless vehicle traffic is generally safe, but special attention must be paid, and human intervention engaged if necessary, at this intersection in order to avoid collisions with emergency vehicles or pedestrians, for example.

Humans ready to intervene

Both driverless shuttles operate with human escorts travelong on board, which are compulsory according to Estonia's Traffic Code. While they are, on the surface, present to explain the driverless techology to passengers, they have also been trained to intervene in the operation of the vehicle if necessary.

"The artificial intelligence must do everything, but just in case, there is a person on board, a human escort, who has a button with which they can stop the vehicle," explained Talvo Rüütelmaa, director of the Traffic Management Department of Tallinn Transport Administration, the agency responsible for the safety of the driverless vehicles. "The artifical intelligence is designed so that if it has any doubts, it will come to a stop, so if anyone steps in front of it, it will stop in any case."

The technology guiding the bus would not be able to yield automatically to an emergency vehicle, as the shuttle only registers the go-ahead signaled by a green light. Why the human escort on board the bus in question did not manually intervene to stop the bus in Monday's close call is another question, however, and one that must be asked of the employee directly, according to Rüütelmaa. The city transport official considered it likely that the human escort may have judged such a sudden stop to be dangerous, although the shuttle buses are traveling at maximum speeds of just 20 kilometers per hour. The buses are capable of maximum speeds of 50-60 kilometers per hour, but will not exceed the 20 kilometer per hour limit during the current testing phase.

The buses' human escorts should also intervene in situations such as the one captured on photo by ERR's photographer, in which one of the shuttles did not yield to a pedestrian green light.

"Currently there has not been one substantial incident," Rüütelmaa concluded. "People who have ridden the bus have been very pleased — they only say that it should go faster."

Police: Driverless vehicles will take getting used to

Police and Border Guard Board (PPA) spokesperson Seiko Kuik confirmed to ERR that they are not aware of any incidents with the shuttle buses that have required police intervention.

He also noted that emergency vehicle drivers themselves must also always take the safety of drivers and pedestrians around them into account, even when responding to a call, and that police working in Central Tallinn are all aware of the new type of vehicle being showcased during Estonia's presidency of the Council of the EU.

Kuik pointed out that driverless vehicles are yet unfamiliar to all road users. "Years ago it was probably a similar situation with the first automobiles," he added.

Tallinn is the first city in which driverless buses will come in direct contact with live traffic. While the twin Easymile shuttles only officially began operating on Saturday, its training began long prior, with a specialist flying in from France to help the vehicles practice traveling along their route.

The driverless buses will not remain in Estonia long, however; the testing phase will conclude at the end of August, after which the vehicles will be returned to France. Following the month of operation, synopses will be compiled on experiences employing the driverless vehicles, based upon which it will later be decided whether or not to continue testing the technology on different routes in the future, according to Rüütelmaa.

Driverless shuttles to operate through end of August

Visitors and residents interested in trying out the driverless buses are encouraged to do so before the end of the month, as no more test runs with the Easymile buses are planned for the rest of the year — in part due to the fact that tram service will be restored along Mere Avenue beginning in September, and also due to the fact that while it may be possible to put winter tires on the vehicles, the French buses as currently equipped would not be able to safely handle icy and wintry conditions.

The driverless buses, which service a limited route between the Mere puiestee (Mere Avenue) stop and Tallinn Creative Hub, will operate from 8:30 a.m. to 5:30 p.m., Monday through Saturday, through the end of August.

The shuttles, which were introduced as part of Estonia's EU presidency, one of the priorities of which is the development of technology and its impact on society, are free of charge for everyone.