Interstate 93 north of Boston is the most important express highway connecting Boston with its northern suburbs, the Merrimack Valley, and New Hampshire. It experiences severe peak-period congestion, a condition partially mitigated by an existing high-occupancy vehicle (HOV) lane that operates in the inbound direction at the southern-most approach to Boston. In view of the success of the existing HOV lane, this study explores implementing a more extensive “preferential” lane between the start of the existing HOV lane and a point south of I-495. The envisioned preferential lane would be reversible and operate in the AM and PM peak directions. By limiting access to the lane based upon occupancy, toll payment, or some other eligibility rule, a significantly higher level of service would be experienced by the preferential lane users, while maintaining or even improving the level of service in adjacent general-purpose lanes. This study discusses at a conceptual level the design, benefits, construction impacts, and other challenges of this examined system.