But Courtney Kanagi, an outreach worker, has learned how to decode bits of urban detritus that most people ignore. She knows what these signs mean: the crawl space beneath the stairs was someone's home.
So Kanagi climbed out of her van and, after a few minutes of poking through the bushes, found a woman sound asleep with a white sheet drawn across her face.
Los Angeles County has more homeless people -- estimated at roughly 73,000 on any given night -- than any other metropolis in the country. It also has a topography in which dense urban areas frequently brush up against tiny pockets of wilderness.
For those without houses, this landscape offers many opportunities for ingenious solutions -- aeries beneath bridges, riverbed encampments, ad hoc tree houses with million-dollar views -- to the problem of where to sleep.
Kanagi and her co-workers at the nonprofit People Assisting the Homeless have become experts in the creativity and resourcefulness of homeless architecture, in the surprising and heartbreaking ways that thousands of people -- up to three-quarters of them suffering from mental illness or physical disabilities -- manage each evening to protect themselves from the elements and from predators and tuck into bed, often in plain sight.
Spend some time with Kanagi and you'll never look at the city's hidden corners the same way again.
To understand the scope of homeless architecture in Los Angeles, it helps to begin with some numbers:
Fewer than 20% of the region's homeless can be accommodated in shelter beds on any given night.
About one-third of them, including thousands of families with children, retreat to motel rooms, basements, garages and parked cars, according to the Los Angeles Homeless Services Authority's 2007 census of homeless.
That leaves tens of thousands of people sleeping outdoors, at the mercy of the elements.
Their options are stark:
* They can hunch in groups on the sidewalk or in alleys behind dumpsters, putting up with disturbances because of the promise of safety in numbers.
* They can find a hidden stairwell or doorway, abandoned building or freeway underpass.
* They can venture into the brush and make their own living spaces, or encampments.
"Nobody can know what it is like until they've lived one night. One night out here," said a woman who lives with her dog beneath a bridge in the San Gabriel River watershed.
The woman, who did not want her name or exact location printed, had set up camp between a concrete bridge support and a chain-link fence on a little ledge above a bike path. She and her husband had created sleeping quarters and a makeshift office, with a mug full of pens and a stack of library books on supernatural events that the woman said she liked to read because they give her comfort.
But she warned that no one should romanticize her situation. Her little abode next to the riverbed might seem out of the way and even peaceful, especially when morning sun etches the landscape with gold. But the woman, who is 34 but is missing teeth and looks much older, said she lives with pressing fear that police will force her to move or that gang members will menace her. And it's frequently cold at night.