From Wikipedia: Hasselt#Transport
Hasselt made Public transport by bus zero-fare from 1 July 1997 and bus use was said to be as much as “13 times higher” by 2006. The town lines (called H-lijn) have been free for everyone including tourists since Tuesday 1 July 1997. Other bus lines are free for the inhabitants of Hasselt while travelling in the territory of Hasselt.
The regional transport services, or so-called Red lines, are free for residents of Hasselt, who can travel without fare as long as they show their identity card to the driver of the bus. Red regional route bus stops are marked with signs indicating the beginning or end of the Hasselt bus network.
Non-residents of Hasselt pay the usual area tariff, except for children under 12 who have zero-fare travel. “Blue” regional lines incur a fare in the normal way.
The mobility policy in Hasselt developed into an example of cooperation between the bus line, the Flemish government and the city of Hasselt, under the motto “the city guarantees the right of mobility for everyone”.
Following the introduction of the new zero-fare policy, the usage of public transport immediately increased by 800-900% and has remained high, being currently more than 10-fold compared to the time of the old policy.