We have taken many trips to Cambodia over the years, focused on the primary schools project.
The project is run with Save the Children and the Provincial Education Office of Siem Reap.
More at http://www.yatesweb.com
The road to Anlong Veng from Siem Reap is about 120 km. At the start of the project, roughly half was decent road, the rest "cart track". And there were land mines by the side of the road for much of the way.