Off the dry, dusty road near Nakhu jail, amidst the junk and machinery, serenely pedalling through the air on their tar bato is David Sowerwine with the boys from his EcoSystems workshop. The contraption looks like a ski lift, bicycle and Santa Claus's sleigh sans reindeers, all rolled into one.

The front has two tandem seats for drivers with a bicycle's gear, pedal and brake system. Behind are passenger seats followed by cargo carriers. The route is fitted with poles through which the cable connects, much like that of a trolley, so when the drivers begin pedalling, the complete entourage lifts off and follows the wire route.

"It would be great if we could have this at various places in Kathmandu," says David, "It does not pollute, is pretty cheap, does not need roads and would add to the charm of the Valley."

The 'wire road' was built by EcoSystems, a company that David and his wife Haydi set up in Nepal in 1996 to work with energy and transport solutions. The American couple have been a fixture in the alternative technology sector in Nepal for nearly 15 years, but they are now heading home. They leave behind a lifetime of work in setting up workable and sustainable technological solutions to Nepal's topographical barriers.

In the early 1990s, after their efforts at solving the garbage problem of the capital were thwarted by red tape, the Sowerwines began to work on wire bridges (tar pul) for rural transportation. It wasn't long before the people from Milche, a village down Bagmati, heard of their work and walked for a day-and-half to Kathmandu to ask if they could have a tar pul.

"We weren't very sure but they sent delegations again and again and finally, we relented," says Haydi, "they were so happy, one villager even sang a song about our bridge at the inauguration." Two weeks after the Milche bridge was built villagers from Gadi near Hetauda came asking for one "just like that".

"Gadi had a real problem because the high school was across the river and , the children had to cross it everyday. One of the villagers was very determined about acquiring the bridge, his mother had drowned while crossing the river. But they didn't have enough funds and neither did we," says David. Help from the German and Canadian embassies has enabled the Sowerwines to bridge distances at critical points across the country.

The average cost of building a tar pul is $15,000. "It is reasonable as it includes the direct cost of labour, steel, safety measures and everything else," says David. EcoSystems has set up more than 30 bridges all over Nepal, most of them in remote areas such as Rukum and along the Kali Gandaki. "We do run risks with the Maoists but we make it a point to clarify things first," says David, "our latest project is installing two bridges in Rukum for user groups. Getting to the countryside with the insurgency is a problem for us especially since the bridges need regular maintenance."

The enthusiasm of the local people helps. "They are so eager, readily participating in building foundations, getting equipments there or contributing whatever they can to make sure the work is smooth," says David. One of their latest projects in Rukum connects a village with a health post which would otherwise take a day to reach.

The tar pul technology has evolved and the Sowerwines are leaving EcoSystems in the capable hands of coordinator Nanda Lal Bhandari and his group of dedicated Nepali bridge builders. But even though they are leaving, the tireless couple are working on yet another project that could help with rural electrification. In their garage in Patan is a pedalling device that generates electricity to light up a 100 bulbs that have the cut-off tops of plastic coke bottles for lampshades.

Says David: "The person who has this can work like a power company and make money generating electricity or recharging batteries for distribution. With some fine tuning, it'll fly."