The original plan was developed by the Friends of POPS, which included addition public spaces in its plans, though there are only so many intersections that can be reasonably built.

The idea is to connect and encourage the use of the arcades, lobbies and galleries that comprise this secret boulevard.

In an effort to unclog Midtown, the Department of Transportation is creating a new public passageway from 51st Street and 57th Street, running through Midtown towers between Sixth and Seventh Avenue.

What if the city built a huge public park in the heart of Midtown, stretching half a mile over seven city blocks, about as big as the first phase of the High Line? What if that park already existed, dating to the 1980s, largely ignored but for the most knowing New Yorkers?

“We’re basically building a new pedestrian avenue in the heart of Midtown, one of the densest, busiest places on Earth,” Transportation Commissioner Janette Sadik-Khan said during an interview last week.

Call it 6½th Avenue.

As Midtown began to creep West toward Times Square in the 1970s, a quirk in the zoning between Sixth and Seventh Avenues led to a string of towers in the middle of the block, all with public plazas, atria or arcades running through them. Everyday, thousands of people traverse this secret boulevard stretching from 51st Street to 57th Street, according to Department of Transportation data. They wind their way between parked cars, oncoming traffic and other obstructions, all in the hopes of shaving a few minutes off their walk and maybe avoiding the crowded avenues on either side.

Now, in an effort to create safer connections between these spaces while encouraging their use and also unclogging the avenues along the way, the Department of Transportation is creating a series of traffic interventions to link up these disparate shortcuts. The result should be somewhere between the Brooklyn Heights Promenade (though the Brooklyn Bridge may be more apt, given the crowds) and the Winter Garden at the World Financial Center. It should be a nice place to pass through, but also possibly to stop for a coffee or lunch, without fear of being mowed down on the way back to the office.

“We’ve been working very hard on the spaces between buildings and now we’re working very hard on the spaces within buildings,” Ms. Sadik-Khan said. “We’re reprogramming underutilized road space while enhancing pedestrian spaces we already have and encouraging their use.”

Update: Community Board 5 Transportation Committee Unanimously Approves 6½th Avenue. >>

The plan calls for creating new pedestrian crossings between these public spaces, which generally are directly across the street from one another. Stop signs will be installed in front of new raised crosswalks. Warning markings—BUMP, STOP, chevrons and stripes—will all alert drivers to the new intersection while curbed cuts and painted street space will make crossing easier and prohibit parking. The goal, as with so many Sadik-Khan-era projects, is improved pedestrian circulation and traffic “calming.” The plan is currently parking neutral.

A tiny piece of the plans was implemented last fall, when a crosswalk was installed in the middle of 57th Street, with a traffic light instead of a stop sign. Commissioner Sadik-Khan said the results have been positive, with fewer illegal crossings and a reduction in accidents.

If it seems strange that all these public passageways should line up, that is how it was always meant to be. These spaces are a legacy of the same era that brought us Zuccotti Park. Privately Owned Public Spaces, or POPS, as they are often called, have been much in the news lately, thanks to Occupy Wall Street. The spaces in Midtown are at once similar and different. While none are as big as Zuccotti, they were all built to add precious square footage to the towers to which they are connected.

Sometimes this meant little more than opening up the lobby to the public, while other times developers would build soaring open air arcades. The stretch contains one of the greatest POPS in the city, the UBS Gallery at 1285 Sixth, the southern anchor of 6½th Avenue, which houses works from the Smithsonian and not only runs north-south but also east-west. These spaces were not only created through POPS bonuses but also The Special Midtown District, codified in 1982 but in the works for almost a decade, that actively encourage developers to have their POPS line up with those of their neighbors. Without this provision, 6½th Avenue would have been almost impossible to create.

Even so, the city might not have developed its plan were it not for a ragtag band of planners, architects and urban obsessive known as the Friends of Privately Owned Public Spaces. The group seeks to promote POPS, encouraging awareness of the nearly 550 POPS in the city while pursuing landlords seen to be privatizing or otherwise violating their POPS—the wrong chairs, signs or hours, for example.

“It’s amazing that we have this vast wealth of public resources that is all too often ignored,” said Brian Nesin, founder and executive director of Friends of POPS. “This is the perfect opportunity to bring life to these POPS.”

It was Friends of POPS that first came up with the idea of connecting these spaces, which the group dubbed Holly White Way, in honor of the influential planner and public spaces advocate who championed the creation and regulation of POPS. Friends of POPS even held a parade through Holly White Way last fall. This was partly a public awareness campaign, partly a celebration of how far the group’s plan had come. The year before, it had partnered with the 54th Street Block Association in trying to make the pedestrian thoroughfare a reality.

The plan was then presented to Community Board 5, which liked the possibility and thus asked DOT to study the feasibility of such a plan, sending a formal request last May. The idea was embraced wholeheartedly by the commissioner and her staff, and tonight they will present their plan to the board’s Transportation Committee. It could be voted on within a week or two an implemented as soon as July.

“I’ve got to give DOT a lot of credit,” Mr. Nesin said. “Most city agencies wouldn’t take an idea presented to them from the public and really, really run with it like this.”

But with Occupy Wall Street taking hold of the city once again after its wintry hibernation, it would seem landlords would be loath to encourage anyone occupying their buildings, even for the simplest and most lawful reasons, like walking to work, stopping for lunch or grabbing a quick smooch from a companion. Not that landlords should have much choice in the matter, as they have already reaped the lucrative benefits of these POPS for decades now. Some built 10, even 20 stories extra atop their towers, earning millions of dollars in rent in the process.

And yet so far none of them seem to be terribly concerned. One official at the Real Estate Board of New York, who was not authorized to speak publicly about the plan since it had not officially been released, said that only one landlord had approached the industry group about the project, and then only to express some minor concerns about loading docks.

According to Commissioner Sadik-Khan, the city had conferred with every building owner and, she said, “the response has been good to neutral.”

That does not mean the project will pass unopposed. While the community board is eager to see what potential these blocks hold, there is still concerns about specifics and implementation. Beyond issues of loading and unloading—on-street parking is not much of a concern, since almost no one lives in this part of town—the board is most worried about increasing vehicular congestion.

Some of these streets, like 53rd Street, are designated through streets, where the DOT tries to funnel crosstown traffic to keep others clear and keep vehicles moving. There are also concerns that stop signs, or even yield signs, could create havoc, particular during lunch or at the end of the work day, when the office rats come streaming out of their dens and into the crosswalks. On the flip side, late at night, when the streets are quiet, will this simply slow down cabs and other cars unnecessarily. The question is, just how disruptive is one extra stop sign?

“These spaces are already here, so we should be doing what we can to improve them,” one member of the community board’s transportation committee told The Observer. “But what are the details? Will it make streets better or worse, more cluttered or less?”

There is also a certain amount of resistance on the board to anything Commissioner Sadik-Khan might propose, given the amount of tinkering she has already done within the district. This includes everything from the re-engineering of Times Square and Broadway to traffic-light cameras and the coming bike share program.

“Change is uncomfortable, especially when you don’t know what the end result will be,” the board member said. “There are some people who may oppose this no matter the merits.”

Should the plan proceed, Friends of POPS views it as a test case for what is possible across the city. Just find the right community group or community board, come up with the right plan, and suddenly a new public park or promenade appears as if out of nowhere. “We want to empower New Yorkers to take ownership of these spaces, especially when the landlords don’t really take care of them,” Mr. Nesin said.

And when they are ready, Ms. Sadik-Khan will be more than happy to help. “Different communities have different jigsaw puzzles that you have to solve,” she said. “This one had the right pieces come into place to create a great new pedestrian right of way.”

mchaban [at] observer.com | @MC_NYC