Despite having left its mark on some 3,000 walls around Philadelphia, the Mural Arts Program has always yearned to work on a larger canvas. Now it's found a way: It just finished wrapping two blocks of Germantown Avenue storefronts in a tapestry of painted stripes, drenching almost every surface in vibrant color - save for the "For Rent" signs.

As big as this project is in scale, the claims for its transformational powers are even more outsized. During a two-hour dedication ceremony last Saturday, a parade of speakers boasted that the dramatic new artwork, Philly Painting - by the celebrated Dutch duo Hahn & Haas - will revive the battered shopping district at Germantown and Lehigh, and turn it into an offbeat tourist destination. "There is no reason," one giddy participant told me, "that this street can't be the next SoHo."

Ahem. A little reality, please.

While speakers like City Council President Darrell L. Clarke were exulting over the "changed street" from the comfort of a nearby community center, Mohammed Sisco, a Bangladeshi immigrant, sat huddled in his underheated store, hoping for a customer who might purchase one of his scented oils, special soaps, or even something from the dollar bin. It was the first Saturday of the busiest shopping month of the year, yet only a trickle of pedestrians wandered the sidewalks outside.

Not that the absence of Christmas shoppers surprised Sisco or his fellow merchants. Once an important retail hub for North Philadelphia, this stretch of Germantown Avenue between Cumberland and Somerset has been skidding downhill for more than a decade. The local Rite-Aid, which is what constitutes an anchor store in these parts, abandoned its corner location three years ago and nothing has taken its place. The avenue's shuttered security gates and plywood-covered upper windows aren't exactly a big retail come-on. Too bad no merchant was available to give his take at Saturday's event.

Whatever you think of murals - and I am not their greatest fan - there is little doubt that this retail strip cries out for an intervention. Make that the whole neighborhood just north of Temple University, which has shed seven percent of its population since 2000.

Purely as a composition, there is much to admire about Haas & Hahn's luminously colored mural. It recalls the famous grid paintings by their 20th century compatriot, the Dutch artist Piet Mondrian, whose jazz-inspired work also celebrates the city. Their grid moves to a hip-hop beat, and that injects the appearance of energy into this anemic commercial corridor. That, if nothing else, argues Alan Greenberger, deputy mayor for commerce, "will be a source of pride to people who use the corridor every day."

But it's naive to think that painting over this depopulated blightscape can do anything more than mask the avenue's failure. It's a feel-good strategy being passed off as an economic development one.

Mural Arts spent $500,000 on the cover-up, including $215,000 from the Commerce Department. Like the program's other murals, it provided employment for local youth and gave them, as one speaker said, "something they can put on their resume." Having celebrity artists Haas & Hahn (their real names are Jeroen Koolhaas and Dre Urhahn) on the project ensures that Philadelphia will be getting international attention for the mural.

Jane Golden, who runs Mural Arts, also believes "what happens afterward matters." The Commerce Department now says it will invest an additional $3.5 million in regular street cleaning and new sidewalks and lighting.

It's an astonishing sum, and it suggests the commerce department doesn't fully understand what makes retail tick.

For starters, retail follows people, not the other way around. This retail corridor failed because it lost its local market. It's a fantasy to think other Philadelphians and tourists will travel to Germantown Avenue to poke around the dollar bins.

It's not impossible to resuscitate a dying shopping street, but there are proven strategies, best articulated by the National Trust's Main Street Program - and none of them involve murals. No shopping street is revived without a strong corridor manager and a strategic plan. Germantown Avenue has neither.

Although the neighborhood conditions are different, North Philadelphia should look to two recent success stories: 13th Street in Center City and East Passyunk Avenue in South Philadelphia. One was saved by a private developer, the other by a nonprofit. But in both cases, the corridor manager started by gaining control over the real estate in the shopping district.

Control is essential because people won't invest their own money to fix up buildings if they feel they will be undermined by a blighted neighbor. On 13th Street, the late Tony Goldman, a New York developer, was able to buy an entire block. It's also possible for a corridor manager to achieve the same result by organizing the district's owners into a nonprofit partnership.

Once Goldman had control, he began to repopulate the upper floors with residents and offices, and install distinctive retail tenants. In little over a decade, he transformed the stretch between Chestnut and Walnut Streets from a prostitute's haven to a dynamic boutique street. Of course, it helped that Center City was already on the rebound.

Even if the city does use the Main Street strategy to help Germantown Avenue, it's not clear that the North Philadelphia shopping district can be salvaged in the near future. It lacks the convenience and good transit of close-in neighborhoods - like Northern Liberties or Hawthorne - that have rebounded. Not to mention that those places hadn't suffered the extreme population loss of North Philadelphia.

Murals have been used as a cheap crowd-pleaser for years. Maybe it's time for city officials to acknowledge that it's just not possible to paint your way out of blight.