For years, planners and residents have been trying to understand why Haddon Township isn't more like Collingswood, the millennial enclave that is South Jersey's answer to Fairmount and East Passyunk. Situated side by side in Camden County, the two towns are old-school commuter suburbs, with small house lots, good sidewalks, and great transit to Center City. They even share a main street, Haddon Avenue, which runs through the center of both.

The pair are models for what smart-growth advocates call walkable urbanism, but Collingswood's downtown is by far the buzzier place. You can stroll for blocks along its part of Haddon Avenue, poking into vintage stores, stopping for coffee, enjoying an al fresco meal at a BYOB. In the evenings, it's common to see pedestrians toting a wine caddy or pushing a stroller.

In Haddon's downtown, known as Westmont, you might not see any pedestrians for blocks.

Westmont is a frustrating example of potential unrealized. Like Collingswood, it boasts a burgeoning restaurant scene and a weekly farmers' market. It has some great blocks filled with early 20th-century storefronts that would look at home on Passyunk Avenue. But those destinations are just lonely islands in a stream of dreary strip malls and parking lots.

As many inner-ring suburbs have discovered, it's no simple matter to bring back a downtown that has been fragmented by auto-centric designs. But after years of sending mixed signals, Haddon appears ready to give it a shot.

On Tuesday, the Township Commission took the first step by freeing up a seven-acre tract in the heart of Westmont for a traditional, town center development.

Once the site of the Dy-Dee diaper laundry, the project has languished for more than a decade because of the town's resistance to affordable housing. The logjam was finally cleared when the commission voted to settle a lawsuit brought by New Jersey's Fair Share Housing Center, which claimed Haddon Township had failed to provide its state-mandated share of affordable apartments.

It's such a good deal it's hard to believe it took this long to reach the agreement. Haddon's chosen developer, Fieldstone Associates, will get to build 252 housing units - apartments and townhouses, mainly - along with 12,500 square feet of retail on Haddon Avenue across from Westmont's PATCO station. Fieldstone has agreed to incorporate 25 units at below-market rents into the development, and the township has promised to create an additional 13 units elsewhere.

If the town center project sounds a bit like Collingswood's five-story, mixed-use Lumberyard development on Haddon Avenue, well, that's no accident. The Lumberyard is just a few steps from the Collingswood PATCO station. The future residents of Fieldstone's town center will be able to zip into Philadelphia in under 20 minutes on a line that runs like a subway at rush hour.

Yet for years, suburbs such as Haddon Township and Collingswood were deeply suspicious of any project that didn't involve single-family homes. Eager to emulate newer suburbs such as Cherry Hill, they also adopted a me-too approach to car-friendly projects in their downtowns.

Nando Micale, an urban planner who grew up in Haddon Township in the 1970s and now lives in Collingswood, vividly recalls watching the destruction unfold in his hometown. One by one, Westmont's solid buildings gave way to convenience stores fronted by parking lots, even though most residents were in the habit of walking to shops.

"It doesn't feel walkable now," he says.

Collingswood suffered less, Micale believes, because its progressive mayor, Jim Maley, embraced smart-growth ideas early and "was able to find creative ways to fight off the auto-centric development." Collingswood was also better at accommodating a variety of housing types, including low-cost rentals. Having that mix, and a more intact downtown, helped leverage Collingswood's revival.

As millennials have replaced first-generation suburbanites, the Collingswood approach is spreading. When Fieldstone first proposed building on the Dy-Dee site in 2006, many Haddon Township residents were shocked by the proposed density. Some even questioned the idea of including shops on the ground floor.

The town spent years - and many thousands in tax dollars - fighting to keep affordable rentals out of Westmont. It even objected when the Fair Share Housing Center proposed a measly eight units in the Rose Hill apartment project, an 80-unit development the Walters Group is building a few blocks from the Dy-Dee site. Despite all the talk about income inequality, many suburbs still act as though it's the job of big cities to provide housing for low-wage workers.

But attitudes are changing. Jason Miller, a Burlington County planner who recently moved to Haddon Township with his wife, welcomes the new developments, even with the affordable units. "This is something this town really needs," he argues, because "the only way to change Haddon is with more people and housing" in Westmont.

Together with several like-minded residents from the area, Miller recently helped start a group called South Jersey Urbanists to promote pedestrian-friendly developments such as Fieldstone's town center. Because Collingswood is a dry town, their preferred meeting spot is Keg & Kitchen in Westmont, where they can legally order a round of beers. The group's numbers seem to grow at every meeting.

Miller was startled when Fieldstone suggested it could meet its affordable-housing obligations by dropping the retail portion of the town center project. What would be the point of building a large development on Haddon Avenue without public uses to anchor the block and draw pedestrian traffic?

If anything, the amount of retail now planned for the Dy-Dee site is too little. Fieldstone's original proposal included twice as much, but it reduced the total to make room for the affordable rentals.

There's no reason the township can't encourage the company to reconsider. Even if township planners had to approve an extra floor for the project, it would be worth it. A five-story building would not be out of context with a seven-story office building right across the street. Density isn't right everywhere, but it's what Westmont needs on the Dy-Dee site.