DOT has proposed painting four new pairs of crosstown bike lanes through the heart of Midtown, an exciting statement and a necessary move in preparation for the launch of bike-share. The lanes would be tightly spaced, located on 39th and 40th Streets, 43rd and 44th, 48th and 51st, and 54th and 55th.

But the design of the lanes themselves is a little odd, changing from painted lanes to sharrows block by block and ending at Eighth Avenue, before the southbound protected Ninth Avenue bike lane [PDF]. We checked in with DOT for more information on how the lanes were designed. All answers via the DOT press office:

Streetsblog: How did DOT decide which blocks to put sharrows on and which to give painted lanes?

DOT: The width of the streets on these crosstown routes varies, in some cases block-to-block. Where there is sufficient width for a lane, we proposed one, and where there is not, we proposed shared lane markings.

SB: Why do the bike lanes go only to Eighth Avenue? Why not connect to the Ninth Avenue bike lane or the Hudson River Greenway?

DOT: The decision to bring the lanes as far west as Eighth Avenue was merely an issue of planning logistics, and we wanted to address the Midtown core at the outset. There is nothing in the proposals that would preclude an extension and in fact these streets were first considered based on the viability of potential westward extension.

SB: Why is there a more frequent spacing of crosstown pairs in this Midtown section than further downtown, where crosstown bike lanes are painted every ten blocks?

DOT: The spacing is necessitated by the density and major trip generators (e.g. Grand Central, Port Authority) in Midtown.