Details are starting to emerge about how Seyfullo Saipov planned Tuesday's attack on the bike path in Lower Manhattan.

WNYC's Robert Lewis and Beenish Ahmed spoke to All Things Considered host Sean Carlson about questions that have arisen about Saipov's use of surveillance and how bicycle lane safety measures may have prevented the deaths.

Below, an image of a typical intersection on the bike path, and an intersection with the sort of metal bollards advocated for by activists.