Granite and concrete blocks are installed as part of Operational Projects as hardening in order to provide safety for pedestrians. Many granite blocks have been repurposed from bridge rehabilitation projects across the City. These blocks are a sustainable solution that integrates seamlessly into New York City’s urban environment. NYC DOT also purchases new blocks when needed.
There is quite a bit of contrast between the road and sidewalk, if someone is driving on the sidewalk and don’t see the rocks then maybe they’ll learn not to drive on the sidewalk next time