Drivers using express lanes to quickly navigate highways through Colorado’s Rocky Mountains can expect to pay more or less depending on traffic, as part of a new “dynamic tolling” system coming later this fall.

The Colorado Department of Transportation said in a news release that the new tolls will be similar to current rates depending on the time of day, ranging from $1.50 to $4.75 on the South Gap segment of the Interstate 25 between Monument and Castle Rock and up to $9 on the South Gap segment of Interstate 25 between Monument and Castle Rock. Mountain Express Lane segment of westbound Interstate 70 between the Veterans Memorial and Empire tunnels.

However, starting in late fall, tolls will be adjusted based on traffic volume. rather than fluctuating in a predictable way, with higher tolls designed to minimize traffic in the express lanes during peak hours.