At the top end of Gurney Street in Fairhill, Philadelphia, there's a dirt path that forks through some trees and winds behind an old car repair shop, down to the rail tracks below.
Follow the path and you'll find a makeshift shooting gallery under a bridge, where heroin addicts gather out of sight and the ground is a sea of used syringes, cookers and needle caps. Users stand around a wooden table to fix, tying on tourniquets and tapping in the crooks of their arms to bring up their veins. One man leans into a mirror to find a spot on his neck, carefully pushing a needle through the skin and rolling back into a chair, his eyes glazing over. Others line up along a long steel beam that forms part of the bridge, unwrapping fresh syringes and preparing to inject. For anyone too nervous, or too far gone, to find a vein, there's a man in a wooden shack a few metres away known as "the doctor", who will stick you for a dollar.
This is "El Campamento", the busiest and most built-up of a handful of hidden-away injection sites along a half-mile stretch of freight track between 2nd Street and Kensington Avenue. For more than 20 years homeless people and drug users have sought refuge in this gulch, and today there are about 70 people living along the tracks and up to 200 passing through every day to shoot up. As nightmarish as it feels, users here say it's a safe place, away from the police and the rest of the public, where people look out for each other and outreach workers visit regularly. Narcan - a nasal spray that reverses overdoses - is never far away.
But next week the city will begin to clear this stretch of track and force the users out. After months of negotiations between officials and rail company Conrail, contractors, guarded by police, will enter at the Kensington Avenue end and work their way up, disposing of an estimated 500,000 used needles, tearing down structures, and eventually paving over El Campamento and installing concrete rubble under the bridges to ward off new camps.