Just for the sake of argument, imagine a very different street-level downtown than the one we have in San Jose today, one designed for lingering rather than quick passage.

As you stroll underneath Highway 280 on First Street, you look up and see an underpass decorated like Lego bricks. On Almaden Boulevard, you see people stopping at exercise hubs, roller-skating, or biking on green lanes.

At the corner of San Carlos and Market streets, you spot a two-story mural designed to resemble a forest. You stop to plug your laptop into a mobile solar energy post. Then you cross the street on a blue crosswalk etched with markings that resemble teeth.

When you finally turn left on Santa Clara Street toward the SAP Center, you see a huge sculpture in the middle of the street, maybe even a shark crushing a hockey stick.

If there’s one word to describe all this, it might be playfulness. The notion is to infuse life into downtown’s streets by giving people things to do and see and enjoy.

A 191-page booklet prepared by San Francisco landscape architectural firm of CMG, the guys who were also picked to help Facebook, turns San Jose’s conventions on their head.

The original planners of downtown’s rebirth 30 years ago wanted a well-mannered center city. These guys embrace thoughtful clutter (see the plan at http://sjdowntown.com/groundwerx)

Filling space

At a recent meeting of the San Jose Downtown Association, which commissioned the study, landscape architect Willett Moss, a likable man in his early 40s, explained that the idea, in its most basic sense, was to fill up San Jose’s empty spaces.

And he did have one word of caution about the massive sculpture: “We’re not saying it should be a shark, but something heroic, something big,” he said. “As long as it’s big, it will work.”

All this is could be described as the hip-hop son of that once-stern master, the Redevelopment Agency, which died suddenly after Gov. Jerry Brown took office three years ago.

With the bankroll from daddy cut off, downtown’s boosters must find their own way, with the Downtown Association trying to serve as Idea Central.

Hence the emphasis on the unexpected, the amusing, the not-too-costly. Are spaces in San Jose — bus stops, say — too hot in the sun? Put up shades hung from pillars.

Is Almaden Boulevard too wide, too designed for cars to foster much street life? Put in exercise hubs that let people do pull-ups or check their pulse.

Does the Fallon Statue sit on an empty island that people rush past on their way to the freeway? Think about putting a downtown dog park nearby.

Vegetation

And everywhere, give people more vegetation and places to linger — blocks, or benches, or even places where they could barbecue in the parking lot while waiting for a game to begin at SAP Center.

After the Downtown Association meeting, I took a walk around downtown with Moss and his colleague, Calder Gillin, and it’s clear they’ve thought long and hard about how to create more street life.

They told me that downtown has good bones, and unbelievable space for an urban center. “It just has to do with that urban scale, giving people a place to linger,” Gillin said “The idea is to make the space inviting and comfortable.”

Homeless issues

The obvious issue that will occur to anyone who reads their document is the problem of the homeless. If you create more places to linger, you’ll create more spots for homeless to sleep.

Ex-Mayor Tom McEnery, who attended the downtown Association meeting, made exactly that point: People have to feel safe first before the new street furniture makes sense.

(Responding to perceived issues of safety, the San Jose police have recently announced a new five-member walking patrol in downtown on weekdays).

Moss and Gillin, meanwhile, are optimistic. As they see it, downtown can be transformed by a collection, or aggregation, of many smaller things. If a piece of furniture doesn’t work, it can be moved.

“We have confidence that these things will be get used,” Moss told me. “All of these little projects can be taken care of by property owners.”

In a profile I did in the 90s of Tom Aidala, the architect who ruled over San Jose’s urban design, I likened downtown to an elegant dinner table that attracted few diners.

Moss and Gillin want to make that dinner table fun, with colorful centerpieces, goofy spoons, asymmetric vases. Will it work? I don’t know. But it’s worth considering.

Contact Scott Herhold at 408-275-0917 or sherhold@mercurynews.com. Twitter.com/scottherhold.