Annex materials - Economic estimation of the impact of rural earthen road construction in Phewa watershed
Along the roads surveyed (42% of the watershed roads network), of the 179 cases of erosion and roadside failure events detected, 155 affected directly the road network and 21 affected agriculture lands. Both have an economic impact for communities in terms of road maintenance costs and losses of agriculture income. Both potential economic losses are calculated separately and summarized then according to 3 different scenarios of road maintenance.
Maintenance scenarios
Based on UNDP (2011), three scenarios of maintenance are considered:
- Labor-based technology for maintaining roads is based on local labor only (LB or Labor-based maintenance). All tasks are done by hand and using hand held construction tools. This technology is sometimes inappropriate in case of large deposits that would be impossible to remove by hand.
- Mixed technology is used to clean roads based on locally based labor (LB maintenance) and machines to clean big deposits (boulders), which could be impossible to remove by hand, requiring equipment-based maintenance (EB);
On the 148 cases of roadside failures, 36 require EB maintenance whereas 112 can be cleaned by hand (Table 5). Moreover, the 7 cases of road shoulder cuts can be undertaken also using LB maintenance.
Table 5: 36 road affected cases need a machine to remove the deposit.
Maintenancetechnology / Count / Ratio
LB / 112 / 76%
EB / 36 / 24%
- Equipment-based technology that proposes to maintain roads using only machine (EB maintenance).
Labor-based costs
The idea to involve community members in the road maintenance process is based on the concept of team-based maintenance of rural road. It is the traditional way of building and maintaining roads in Nepal and has been promoted by many organizations as the most environmentally friendly way and best for local economies as local jobs are created through the road construction and road maintenance. The International Labor Organization (ILO) promoted it and has already piloted team-based maintenance in Nepal (Van Dissel, 2009).
The volume removed or repaired by one person in one day is defined by Government of Nepal (2014). Daily wages in the Pokhara district are also given by the government. Operation cost (per volume of material to remove or repair) depends therefore on these values and is calculated for the worst-case situation (Table 6). Assuming LB maintenance guarantees by road maintenance groups (Government of Nepal, 2014), cost of tools and safety equipment, different allowance and the accident insurance is estimated at 30 USD.km-1.year-1. Additional cost, as workers transport costs, would be considered at 50 USD.km-1.year-1 (Government of Nepal, 2014). Considering an annual maintenance volume per kilometer of about 39 m3.km-1.year-1 (as estimated before), this amount would give an additional cost of 2.05 USD/m3 (80 USD.km-1.year-1 per 39 m3.km-1.year-1), or the total operation cost (Table 6).
Table 6: Labor-based technology operation costs calculated according to the concept of team-based maintenance.
Labor-based maintenance parametersMaintenance work / Remove deposit material on road / Repair road shoulder
Task rate (m3/workday) / 3 to 4 / 2 to 3
Cost rate -Daily wage in Pokhara district (USD/workday) / 5 / 5
Operation cost (USD/m3) / 1.67 / 2.5
Additional cost (USD/m3) / 2.05 / 2.05
TOTAL operation cost (USD/m3) / 3.72 / 4.55
Equipment-based costs
The use of three types of machines of different production capacity is compared for EB maintenance. The total cost rate (Table 7) of each machine depends on the machine hire rate (Government of Nepal-Ministry of physical infrastructure & transport website, 2015), the fuel consumption (Caterpillar Inc., 2001) and the operator hourly wage. We consider moreover 1 USD as the price for 1 liter of fuel in Nepal. Then, machine production capacities (task rates) are defined according to literature and website (Methvin, 2015; Abeli, 2009) to calculate operation costs (Table 8) for each machine. Note that the references come from different sources, especially for the fuel consumption document and the machine for rent proposed by the Government of Nepal; power and consumption equivalence were therefore checked.
According to UNDP (2011), the cost of machine transportation from rent source to use point and back is about 1.92 USD per kilometer, which amounts, for the total watershed of earthen road network maintenance, to a fixed cost of about 595 USD.
Table 7: Cost rate estimation for each machine.
Machine Type / Hire rate(USD/hour) / Operator cost (USD/hour) / Fuel consumption (L/hour) / Fuel cost (USD/hour) / TOTAL Cost rate (USD/hour)
Caterpillar excavator 307 B (0.3 m3 bucket) / 6 / 1.5 / 8 / 8 / 15.5
Daewoo excavator Solar 130LC-V (0.5 m3 bucket) / 18 / 1.5 / 9 / 9 / 28.5
Caterpillar bulldozer D6H / 30 / 2 / 21 / 21 / 53
Table 8: Equipment-based technology operation costs.
Equipment-based maintenance parametersMachine Type / Cost rate
(USD/hour) / Task rate
(m3/hour) / Operation cost
(USD/m3)
Caterpillar excavator 307 B / 15.5 / 10 / 1.55
Daewoo Solar excavator 130LC-V / 28.5 / 23 / 1.24
Caterpillar bulldozer D6H / 53 / 129 / 0.41
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