The state Department of Transportation says bridge tolls on State Route 520 have brought in $50 million since tolling began a year ago.

Saturday is the first anniversary of the electronic tolling system.

Transportation officials predicted traffic on the bridge would be cut in half as drivers found other ways across Lake Washington. But a year later, bridge traffic has risen to 70 percent of pre-toll volume.

The tolls are being collected to help pay $1 billion needed for construction of a new bridge.

Transportation officials say the tolls have also encouraged more commuters to take the bus instead. King County Metro and Sound Transit have added 140 daily trips across the bridge to accommodate new bus riders.