I’m in Massachusetts for a folk festival. The town I’m in, Marlboro, has granite curbs (kerbs) almost everywhere. I had first seen these many years ago in New Hampshire, but apparently they are quite common in New England. Most historic districts require them, and they are used in many other areas as preferred by the town or city.

There are distinct advantages of granite curbs over the traditional western model of curb and gutter:

• granite curbs last practically forever
• granite curbs can be moved inward to narrow streets or widen sidewalks
• gutters are not required

If a western street is changed, the transportation agency will almost always neglect the sidewalks in part because they don’t want to move curbs. Digging up and discarding curb and gutter is expensive and wasteful. Granite blocks are about 16 inches deep, but depth and width may vary. With granite curbs, simply dig a new trench and move the curb blocks to the new trench. If the curb needs to be reset, it can be done in short sections rather than tearing up long stretches of concrete.

Granite for curbs is more expensive on initial installation than concrete, roughly 1.5 times. However, concrete curbs may last as little as 30 years, while granite curbs are as much as 200 years old. Life cycle cost analysis indicates that granite is far less expensive in the long run than concrete, because the concrete must be removed, disposed of, and replaced. Looked at over a long period of time, granite is by far the most cost effective. It may be that granite would be more expensive in California. New Hampshire, after all, is ‘The Granite State’.

So called ‘modern’ curb and gutter is claimed to direct water flow away from the roadway to reduce roadway damage, but after looking at dozens of website about this design, not a single one actually explained why gutters were better than roadway profile where the drainage is to the granite curb. I suspect it is one of those street design engineering mythologies that has propagated without any research or proof.

Note that in the photo below, concrete sidewalk has been replaced or patched several times, but the granite curb is original.