In livable streets/tactical urbanism circles, a sneckdown is (sorta) naturally occuring traffic calming that demonstrates that a street is wider than it needs to be. A neckdown or curb extension is a traffic calming measure where the curb line is extended into the street to slow cars and shorten the time that pedestrians need to be in the street to cross. Sneckdowns are neckdown-like snow acccumulations that appear when plows don’t plow right up to the curb.
The picture above is the intersection of Hammond St. and Ward St. just north of Commonwealth Ave. Hammond goes north/south from left-to-right across the picture. Ward runs east/west from top-to-bottom.
Hammond/Ward is a terrible intersection. It’s way too big. Tightening it by building out the intersections would improve pedestrian safety crossing the intersection and would slow cars that turn from one street to the other.
The sneckdown demonstrates that the intersection operates even when substantially narrowed (at one point). Look at how much of the crosswalk is eliminated!
This picture is Beacon St. and Centre St., in Newton Centre. Beacon runs east/west left-to-right. Centre runs south/north from top-to-bottom.
The sneckdown is in the top left; it substantially reduces the one eastern Beacon Street crossing. There are no tire tracks through the sneckdown, largely because there is a slip lane for northbound traffic on Centre turning right/east onto Beacon, indicating that it has no negative impact on vehicular traffic.
What these sneckdowns show us, vividly, is that we could have safer streets with some relatively minor design tweaks.