The air in the Union 76 truckstop, or transport cafe, at Harrisburg, Pennsylvania is a concoction of fried food and testosterone. It's a place where the toilet seats are left up and the groans from a blue movie fight with the noise from Space Invader games.

Parked outside the television room is an old articulated lorry. Its days of hauling goods have been given up to God. Eight years ago its 40ft trailer was converted from cargo carrying to chapel, and pews now line up where packing cases were once stacked. On the side, in large blue lettering, are the words 'Mobile Chapel'.

Harrisburg's truckstop was the first in America to add a chapel to its list of amenities, once the Transport for Christ mission had persuaded the owner that the chapel would not scare truckers away. Now it is as much a feature of the Union 76 stop as the movies and the slot machines.

Since the mid-Eighties the missionaries of the road have opened 14 fixed sites from Ontario, California to Ontario, Canada. 'Before we had permanent sites, we had mobile chapels which would travel from truckstop to truckstop,' said 45- year-old Steve Pearson, one of two chaplains at Harrisburg. 'But the truckers would never know where we would be and it was hard to get into some stops.'

For Steve life as a Christian and life as a trucker sat uneasily together. Pulling over at a truckstop was rarely a pleasure. He didn't do drugs and had no interest in the prostitutes who hung out waiting for the cowboys of the open road. 'Satan's territory,' he declared.

Following a serious accident, Steve gave up trucking for a job as a salesman, but the call of the road proved too strong and now he spends one week in two working at the very truckstops he so despised. Travelling the 100 miles from their home to Harrisburg every other week, Steve and his wife, Patty, spend seven-day stretches in a cramped compartment at the front of the trailer chapel.

For Steve it is familiar ground. 'I love the smell of diesel fuel. After I stopped driving trucks, I found it hard to sleep without the rumble of the engines,' he said.

A pull-out bed is barely big enough for two, a desk and chair the only space to prepare sermons for the Sunday morning service and a microwave the only way to heat up home-cooked meals. 'The Lord blessed me with a wife who can cook,' Steve said. 'I get considerably better food than the truckers.'

Mobile churches were the brainchild of Ralph Winter, a pastor who diagnosed America's 8.5 million truckers as 'one of the largest groups of unreached (sic) people in the world'. Wanting to see 'truckers touched by Christ' he started up Transport for Christ in 1961. Thirty- three years on, it is a multi-million dollar enterprise with plans to open more than 100 chapels (at dollars 100,000 apiece) in the next six years.

Like the truckstops, the chaplains work round the clock and the chapel never closes. 'One night we were asleep and we heard someone come in. I saw a guy with North Hill Motorcycle Gang written on his leather jacket. To be honest I was a little fearful, but you often only get one chance to help someone, so I went out,' remembered Steve, who wears biker-style boots and a brass belt buckle bearing a cross.

'When I went out to the chapel he had his head in his hands crying. He talked for an hour and a half. He was married, he had had a relationship with another woman, and he knew he had to deal with his guilt. I try and listen more than advise.'

After months, even years of anguish, drivers knock on the chapel door, looking not for religion, but for someone to talk to. 'Some skulk up to you, worried that their macho image might be destroyed talking to the chaplain, so you have to respect them,' said Steve.

Marital stress, loneliness and family issues take their toll on long- distance truckers. Away for weeks at a time, with only the radio for company, their minds often begin to wander. 'There isn't a truck driver who hasn't wondered if his wife is sleeping with someone else that night,' admitted 'Jimmy', a trucker and convicted murderer, whose estranged wife lives in Mexico with his children.

'I like coming to this stop,' he added. 'The chapel makes a real difference. I have time to do a lot of thinking and prayer.'

The breakup with his wife has hit Jimmy harder than spending time in the California State Penitentiary - where he says he found God - and by the time he arrived at Harrisburg he was depressed and desperate to talk to John Lentz, the other chaplain.

John, 38, a former hot-rodder and delivery driver, has helped dozens of lonely truckers, who are undaunted by his jeans and leather waistcoat. He is as happy to talk about V8 engines as about the Book of John. In two-and-a-half years as Harrisburg's pastor, John has witnessed 60 truckers become Christians. 'The truckers live in a world virtually untouched by the church. They can listen to Christian radio stations, but they can't exactly pull over on a Sunday morning with their 18-wheelers and pop into a church.'

The Sunday morning service is becoming more and more popular. 'I have had as few as three here for a service,' John said, as a healthy turn-out of 12 truckers dribbled into the chapel. He recruited his congregation by knocking on cab doors.

Jeannie Manners, just 5ft 2in but the driver of a mammoth pounds 50,000 Freightliner 'rig', played a worn upright piano to accompany a flat rendition of 'The Solid Rock'. The sound of air brakes and diesel engines added percussion.

After the service, plaid shirts and paunches were everywhere in the restaurant. The Christians stood out, their heads bowed in prayer before eating. 'I think that's real nice,' a waitress smiled. 'We don't see a lot of that in here.'

Since Transport for Christ parked their chapel at Harrisburg, things have changed. Drug use and prostitution are virtually non-existent and few truckers resent the presence of the church. 'This place is really different,' one trucker bellowed. 'You don't even get propositioned in the washroom any more.'

(Photographs omitted)