From the inital group of 17, only 4 of us did travel through Nepal.
We had a nepalese guide, Tongka which was really a very nice guy, telling us a lot about nepalese lifestyle and habits.
In order to reach the Trisuli river, 80 km south from Katmandu, you have to leave the Katmandu Valley. The road, which raise until a 6000 ft high pass, was definitively the most dangerous and scarry I saw since Delhi.
This is the main transit road between Katmandu and North India.
On top of the same TATA trucks and Indian driving habits, you follow permently a 500 ft deep precipice.
On local bus or trucks, you may travel either inside, either on the roof of the vehicle. Some says travelling on the roof is safer : in case the driver lose control, you may have time to jump before it crash at the bottom of the precipice.