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← Uses of Nepal’s Slopes

Green roads instead of dozer roads

Hill roads built to fit the slope, with the dug soil used again, drains from the first day and plants on the banks, instead of a bulldozer pushing the hillside into the valley.

Who can take it up
Business, Local government
Where
Chure, Middle hills, High hills
The slope
Protects the slope

How it works

A dozer road is made by driving a bulldozer along the hillside: it cuts into the slope and shoves the loose soil over the edge, often with no drains. In the first monsoon, water runs down the road, and the steep cut above and the loose spoil below give way.

A green road is planned to move as little earth as possible. Its line is chosen to cut as little into the slope as it can (in Bhutan, moving a road’s centre line 1 m towards the valley cut the digging by about a third), and it is kept narrow. The soil dug from the uphill side builds up the downhill side, balancing cut and fill, so none is tipped down the slope. Drains, culverts and outlets are built before the first monsoon. The banks are planted with grasses, shrubs and trees (bioengineering), with small stone or gabion walls where needed.

Nepal’s first green roads were dug by hand by local workers. Bhutan does the same with excavators, which load the surplus soil onto trucks and carry it to chosen dumping sites.

Where it has worked

  • Bhutan’s Department of Roads (Bhutan, since 1999): With the Dutch organisation SNV, Bhutan builds feeder roads by Environment Friendly Road Construction: excavators instead of bulldozers, spoil carried to chosen sites, drains and gabion walls in the first contract. Such a road cost about 30% more to build, but lower repairs and monsoon damage made it the cheaper road after about nine years (2005). research4cap.org
  • FAO study of forest roads (Bhutan, since 1998): The FAO timed an excavator and a bulldozer building forest roads. The excavator cost US$9.28 a metre against the bulldozer’s US$6.07, but the study found it far better for the environment and warned that the bulldozer’s saving was short-lived, since the slopes it left would keep failing (1999). fao.org
  • Roads for Water (Tigray and Amhara, Ethiopia, since 2015): MetaMeta, Mekelle University and the Ethiopian government redesign road drains to send runoff into ponds, check dams and fields instead of gullies, and protect springs uncovered by road cuts. By 2020 the programme reported over 4 million people reached and 55 institutions using it; at one site, gullies up to 30 m deep were filled in. globalresiliencepartnership.org

Why it fits Nepal’s slopes

Nepal’s hills are steep and wet: 93% of its landslides happen in the four monsoon months (Robson and others, 2025), exactly when a dozer road’s loose spoil and missing drains fail. Green roads were first worked out here, in Nepal’s hills, and Nepal has developed its own simple, labour-intensive bioengineering with local plants (Dhakal, 2011). Building by hand also suits hill villages: the money spent on digging is paid to local people as wages.

In Nepal now

Green roads began in Nepal. From 1988, engineers on GTZ’s Dhading Development Project built roads by hand with balanced cut and fill, and the name “Green Roads” came from them (SIDeF; Department of Roads). The UK-funded Rural Access Programme later built district roads the same labour-based way with bioengineering, paying poor families in road-building groups (Itad, 2018). But most of the local road network, which grew from 4,780 km in 1998 to 57,632 km in 2016, was dug by bulldozer, often by the dozer owners themselves, without grading or drainage (Sudmeier-Rieux and others, 2019). Local governments now build these roads, and their engineers often go by rule of thumb (Robson and others, 2025). The new step: a municipality that requires green methods on every road it pays for.

Where in Nepal

Any municipality in the Chure, middle hills or high hills that builds or widens earth roads, starting with roads across slopes that already slide each monsoon, like the Palpa, Gulmi and Arghakhanchi roads hit in 2020 (Kathmandu Post), and new roads into villages that have none yet, before the dozers arrive.

Safe for the slope?

This use cuts landslide risk: less digging, no spoil tipped downhill, water led off the road in lined drains, and planted banks. Roads matter: in Sindhupalchok, 45% of monsoon landslides were within 100 m of a road, against about 21% of earthquake ones (McAdoo and others, 2018), and in Darchula most failures along new roads came as they were cut, often on dry days (Awasthi and others, 2026, not yet peer-reviewed). What would add risk: a road “green” in name only, with drains emptying onto a bare slope, or spoil dumped in a gully for a stream to wash out.

What it costs, and who pays

Building green costs more at first. Bhutan’s green feeder roads cost about Nu 4.8 million (about US$110,000) a kilometre in 2005, about 30% more than its old dozer roads, and paid back in lower repairs after about nine years (Visser and others, 2005). In the FAO’s 1998 Bhutan test, an excavator built road for US$9.28 a metre against US$6.07 for a bulldozer. What a green local road costs per kilometre in Nepal, next to a dozer road: no reliable figure. Local governments pay; on labour-based roads much of that money goes to local workers as wages.

The catch

  • Costs more up front, and pays back only over years.
  • Politicians are judged on road length and width, not stable slopes.
  • Local governments often can’t pay for land, so cuts are made steeper.
  • Needs engineers who check work on site, and upkeep of drains and plants after.

Where to learn it

SIDeF, the consultancy founded in 1994 by engineers of the Dhading green roads, has trained engineers, overseers and contractors in bioengineering and environment-friendly road building. The Department of Local Infrastructure (DoLI) supports local road projects, and the Institute of Engineering’s Centre for Disaster Studies is preparing road-cut slope guidelines with it (Robson and others, 2025).

First steps

  1. Walk a new road near you after the monsoon: note where spoil was tipped, where drains are missing and where it slid.
  2. Ask your ward office who designs and checks the roads it pays for, and whether it requires drains and spoil sites.
  3. Visit a labour-based road, such as one built in Dhading or by the Rural Access Programme, and compare it with a dozer road.
  4. If you study civil engineering, take a bioengineering or green road training, or join a road users’ group that keeps drains clear.

Sources

Facts checked October 2026. The places and projects named are examples, not recommendations.