January 10, 2012

Key Highway / Light Street Update

An intersection design that actually works -
Without the drama
The intersection of Key Highway and Light Street is totally inappropriate for a roundabout. Here's a simple design solution that actually works. Essentially, the two existing islands on Key Highway and Light Street would simply be enlarged to tighten up the intersection of northbound Light Street and the southbound left turn movement that crosses over it. This very tight intersection with minimum length pedestrian crosswalks would be controlled by a simple two-phase traffic signal. Pedestrians would cross Key Highway while Light Street through traffic moves, and would cross Light Street while Key Highway traffic moves - so simple even a BC-DOT employee could do it.

A third median island would then be constructed to totally remove southbound Light Street from the intersection. This island would start at Montgomery Street and extend as far north as desired. Essentially southbound Light Street would function as a quiet single-lane local service road with parking and any other appropriate desired traffic calming measures such as speed humps and "Stop for Pedestrians" pylons. It would also be possible to extend the southbound Light Street island separating "arterial" traffic destined for Key Highway and "local " traffic destined for Federal Hill as far north as Conway Street. While this would be an excellent way of minimizing the heavy traffic exposure on the adjacent land uses (Christ Church Apartments, Harbor Court Condos/Hotel), it would tend to make this seem like a permanent solution.

This design should be much cheaper than a roundabout. The railroad track wouldn't even need to be removed, unless the city wanted to. It would probably be preferable to keep this as cheap as possible, in keeping with the idea that it would only be temporary until the city comes to its senses and decides to create a more permanent solution with a narrower Light Street along the entire Inner Harbor.

Proposed intersection design, with a new median island starting at the Montgomery Street intersection (left/south end) to totally separate southbound Light Street through traffic from the Key Highway intersection. This median could be extended as far north (right) as desired. The two existing islands (center) would also be enlarged, with a new "bump out" (center left) to tighten up the remaining intersection as much as possible. The Science Center is at the lower right.


  1. Makes sense to me. Just make sure the islands aren't so big they preclude bike lanes, especially for southbound bikes on Light Street, both those turning left onto Key Hwy and those continuing south on Light.

  2. Dear Mr. Neily,
    I live in Christ Church Harbor Apts. in the 600 block of Light St. I came upon your blog quite by accident when I "Googled" the roundabout. I was immediately impressed with the simplicity, effectiveness, practicality and economy of your plan. This traffic drama takes place daily beneath my balcony. Your plan solves the existing problems and the anticipated problems of a roundabout. Is City Councilman Bill Cole aware of this? If he has not completely committed to the roundabout, he could help.
    Alan Cherry 410-659-7117 I have 2 suggestions. Contact me if you like.

  3. Very simple and elegant plan! I hope you're aware of and possibly attending the open house tonight:

    -- Key Highway and Light Street Roundabout Project
    The Baltimore City Department of Transportation (DOT) is hosting a Community Open House to discuss the proposed roundabout

    DATE/TIME: October 10, 6 pm – 8 pm
    PLACE: Maryland Science Center, 601 Light St., 1st floor classroom; Key Highway entrance