Use of the Trolley Assist Module in MineSight Haulage
MineSight Haulage uses material routings to generate cycle times and to ascertain haulage requirements. It combines
with MineSight 3D (the graphical user interface) and MineSight Interactive Planner (the reserves tool) to create a
haulage network graphically, rather than by using ASCII profile files. The tool will soon be integrated with MineSight
Schedule Optimizer (the short term mine planning and scheduling tool) and will allow short term schedules to be created
considering their haulage needs.
Several mines already use MineSight Haulage for their haulage needs. It pre-calculates the times for each road segment
and uses a combination of haulage nodes and roads to find the best haulage path through the network. This paper
explains the Trolley Assist module of MineSight Haulage.
Trolley Assist is an alternative power source for diesel haul trucks, which are outfitted with pantographs to draw power
from an overhead power line. This allows trucks to use the diesel generator on level or downhill drives while employing
electric power for climbs. The greater power of the electric drives speeds the truck faster on the uphill drives. The diesel
engine can idle during uphill drives, reducing fuel consumption. This is especially useful for deep mines with many uphill
drives. Siemens estimates that loaded travel on uphill grades accounts for 70-80% of a truck’s fuel consumption. Using
Trolley assist instead of diesel drives is faster and saves fuel.
The speed on a grade is given by (equation 1):
v= Power / tractive effort = Power / Gross Weight * 9.8 * Grade(%)
settInG uP trolley AssIst In MsHAulAGe
Setting up trolley assist in MSHaulage requires these minimal additional details:
1. Route segments appropriate for trolley assist are tagged as ‘Available’ in the ‘Trolley Flag’ column on the
2. Maximum trolley speed on the road denotes the speed limit for a trolley assisted hauler on that road.
3. Trolley Utilization of the road is a percentage to account for maintenance of the trolley assist infrastructure.
4. Pantograph mechanical availability, set on the equipment panel, pertains to the mechanical availability of the
5. Operator efficiency, set on the equipment panel, conveys how fast the hauler operator tacks the pantograph
onto the overhead lines. For example, if an operator has a 95% efficiency, it indicates that 5% of the trolley assist
haul route is traveled by diesel traction as the operator couldn’t tack the pantograph at the start of line.
6. Trolley fuel burn, set on the equipment panel, is the idle fuel burn rate of the hauler when the trolley assist is
7. Trolley power, set on the equipment panel, is the power of the hauler’s AC/DC motor, which is used for the ad-
8. Maximum Speed on trolley, set on the equipment panel, denotes how fast a hauler with trolley assist can travel
while trolley assist is engaged. The speed calculated from equation 1 is capped to this value.
1-3 are input in the Routes panel (Figure 1) while the rest are input in the Equipment panel (Figure 2 and 3)
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á Figure 1
Figure 1 Routes panel in MSHaulage
Figure 3 á
Figure 2 Equipment panel in
¥ ¥ ¥
Figure 3 Trolley Assist inputs in
ß Figure 2
HoW MsHAulAGe cAlculAtes tHe cycle tIMe
MSHaulage calculates the times of all road networks by assuming trolley assist is unavailable. It then checks for specific
route segments where trolley assist is available. It calculates the time taken by the hauler using trolley assist. It calculates
speed in that segment from available power to the AC motors, road grade (which includes rolling resistance), and gross
weight of the truck (empty weight + payload). Note that the ‘GrossWeight’ attribute in the list of hauler attributes
pertains to the empty weight of the truck. The time is calculated based on the distance traveled in that route segment
and the speed. The time is weight averaged with the non-trolley time based on the efficiency and availability factors
to get the actual time used by the truck to travel the trolley assist route. To illustrate, let’s assume that t1 is the time
taken by a conventional hauler to cover the route and t2 is the time taken by the trolley assist hauler. If the pantograph
availability, operator efficiency, and route trolley utilization is 90%, 90% and 80%, respectively, then the total availability
of trolley assist over the route is assumed to be 0.9*0.9*0.8=64.8%
Then the time taken by the trolley assist hauler, t = (64.8*t2+33.2*t1)/100
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A sIMPle exAMPle to IllustrAte trolley AssIst
To illustrate use of Trolley Assist in MineSight Haulage, let’s consider the small haulage network shown in Figure 4. The
road from Pit Bottom to Tie has no trolley lines so diesel is used. The road from Tie to Pit Exit has trolley assist power lines
so the trucks use trolley assist electric power from Tie to Pit Exit. The roads from Pit Exit to Mill and Waste Dump are flat
and don’t use trolley assist. The setup of the nodes and road segments in MSHaulage is in Figure 4 below.
Figure 4 Sample Haulage network to
illustrate trolley assist
ß Figure 4
Two equipment sets both using the same shovel for loading were considered. ESet-1 was a truck outfitted with an electric
motor and pantograph for trolley assist; ESet-2 had the same truck without trolley assist, as shown in Figure 5 below.
ß Figure 5
Figure 5 Equipment sets
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Compare the cycle times of both the equipment sets (Figure 6). The equipment set with trolley assist has lower cycle
times compared to the equipment set without trolley assist. This is because the trolley assist allowed for faster speeds
on a portion of haul road equipped with trolley assist.
â Figure 6
Figure 6 Snapshot of cycle times
To understand the implications of this increased speed, let’s assume that we need to route a cut from the pit bottom
to the different destinations. The cut has 456555.85 tonnes of waste and 526740.68 tonnes of ore, which are routed to
Waste Dump and Mill destinations, respectively. We would need to mine this cut in 120 hours (1 week @5 days a week
and 24 hrs a day).
The figures below (Figure 7a and b) show the material routing report for both the equipment sets. The table below (Table
1) shows the relevant data extracted from both the material routing reports.
Figure 7 a & b á
Figure 7 Material editor in MSHaulage - a) Results using ESet, b) Results using ESet1
Material Tonnes Cycle Time Num Trips Num Truck Hrs
With Trolley Assist
Waste 456555.85 19.71 2369.05 9.66 984.98
Ore 526740.68 22.48 3044.74 12.71 1295.44
Without Trolley Assist
Waste 456555.85 27.85 2639.05 12.18 1242.01
Ore 526740.68 27.62 3044.74 15.62 1592.99
Table1: Comparison of Material routing results
The material routing reports show that with trolley assist, the mine uses fewer trucks. Since both trucks’ payloads are
the same, they would have the same number of trips. However, with faster haul times, trucks equipped with trolley
assist make more trips per day compared to conventional trucks. So the number of trucks in use goes down. Similar
comparisons of the truck requirements can be made to see if trolley assist may be helpful. MSHaulage can help in this
analysis. The material routing reports also output the power consumption, which can be used by mine planners to
ascertain their trolley assist power requirements.
MSHaulage successfully determines the effectiveness of various haulage systems. The trolley assist module helps a mine
planner to check if a trolley assist might help the mine.
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