The Northwest Corridor Express Lanes in Cobb and Cherokee counties will open to traffic mid-morning Saturday. Here’s what you need to know.

The lanes: The Northwest Corridor consists of 30 miles of toll lanes on I-75 and I-575. The lanes are separated from regular traffic. They stretch from Akers Mill Road to Hickory Grove Road on I-75 and from I-75 to Sixes Road on I-575.

The lanes are reversible – they will carry traffic into Atlanta in the morning and out of town in the afternoon.

How to use them: You must have an active, registered Peach Pass on your vehicle, which allows the State Road and Tollway Authority to assess the toll electronically. You can register for a pass at www.peachpass.com.

The toll: For the first 14 days, the cost is free (you still need a Peach Pass). After that, the minimum toll on the lanes for most of the day is 10 cents a mile. The toll will rise as traffic gets worse.

There is no maximum toll. But state officials expect the cost to be minimal at first, as the lanes likely will be lightly used.

Overnight (roughly midnight to 5 a.m.) the cost is just 50 cents per trip, regardless of the length of the trip.

More information: Visit www.peachpass.com.