Motorists took more than 610,000 trips on the I-75 South Metro Express lanes in their first four months of operations, the State Road & Tollway Authority announced Tuesday.

The reversible toll lanes in Clayton and Henry counties opened Jan. 28 and topped the 610,000-trip mark through May 31. The tollway authority also announced it issued 59,395 Peach Passes – which are required to use the lanes – from January through May.

SRTA originally projected an average of 6,000 trips per weekday after six months of operating the new lanes. In May motorists averaged 7,600 weekday trips.

The two new lanes are open to northbound traffic in the morning and to southbound traffic in the afternoon and evening. Motorists pay 10 cents to 90 cents per mile to use the lanes, depending on traffic. The current average toll is 50 cents – the minimum cost of a trip.

The South Metro Express Lanes are part of a larger network of tolled express lanes under construction or planned throughout metro Atlanta. The Northwest Corridor project on I-75 and I-575 in Cobb and Cherokee counties will open next year. The state also is extending express lanes on I-85 northeast of Atlanta.

Eventually, the network will include express lanes on along the northern half of the Perimeter and on Ga. 400.