A study released by Johns Hopkins last November gained widespread attention for demonstrating that 9-foot lanes are often safer than wider lanes. The researchers note, however, that most state DOTs set minimum lane widths between 10 and 12 feet and require design exceptions for anything narrower. Even in Vermont, where 9-foot lanes are allowed, the researchers found they have not been implemented. Therefore, paving the way to narrow lanes means understanding all the factors that make them challenging in the first place.