Performance Settings

To access this screen:

Select a haul truck item on the Scheduling Setup screen. Activate the Performance tab.

The Performance screen is used to select a performance model type. The contents of the Model Settings group change based on the selected model type.

This screen is provided as part of the Haul Trucks settings.

The following groups of controls are available on this screen, accessible using one of the radio buttons on the left.

Linear – Select this option to define a linear model type.
Rimpull and Retardation – Select this option to define a Rimpull and Retardation model type.

Gradients, Speeds and Stopping Distances

The vehicle speeds are entered with reference to a specified gradient. This is typically the ramp gradient used in the mine and is usually in the range 8 to 10%. The reference gradient should include the Rolling Resistance (RR), which is typically around 2% for a well-maintained haul route. For example, if the ramp gradient is 8% (8 m vertical lift per 100 m horizontal distance) and RR is 2%, then the reference gradient is 10%.

The vehicle speeds are given for the reference gradient for loaded and empty, for up, down and flat gradient scenarios. This allows for all possible combinations of haul route configuration.

The speed on any other gradient can be calculated as a linear function of the speed difference on the flat (loaded or empty) and the speed on the reference gradient (loaded or empty). This is a reasonable linear approximation of the rimpull pull or retardation curves for most haul trucks.

Acceleration distance at the start of each road segment is calculated from the vehicle specifications and vehicle performance curves. This means that if a vehicle is travelling at a constant speed when entering a new road segment and the effective gradient changes, then the accelerating or decelerating force can be computed. This is used to determine the acceleration or deceleration distance and time. The terminal speed for the new road segment depends on:

The length of the road segment relative to the acceleration distance.
The vehicle performance characteristics (speed vs effective gradient).
The effective gradient of the road segment.
The maximum speed allowed on the road segment.

At the end of each haul route, the vehicle slows down at the dumping point or at the loader. You enter this distance as Stopping Distance, and this distance is added to the total length of the haul. You can see this by inspecting the haul route log.

Sourcing Rimpull and Retardation Model Parameters

Rimpull and retardation data is supplied by haul truck manufacturers. Refer to their data tables for the relevant modelling parameters if you want to use this option.

Defining and Using Stopping Distance

Stopping distance is the distance the truck takes to decelerate at the end of the outward journey to the destination and on the inward journey to the loader.

In the case of the outward journey, this distance is added to the route length and represents the turnaround distance when dumping. Similarly, a turnaround distance is also added to the inward journey.

Acceleration or deceleration distance (AccelDist) is computed in your product using the vehicle performance settings and the rimpull/retardation curves. If AccelDist is greater than the road segment length (Distance), then the terminal velocity (VEnd) for the road segment is:

Less than the maximum speed (Vmax) if VStart < Vmax.
Greater than the maximum speed (Vmax) if VStart > Vmax.

Where:
- Vmax is the minimum of the theoretical speed (calculated from the vehicle performance settings, effective gradient) and the maximum allowable speed for the road segment.
- VStart is the vehicle speed at the start of a road segment, which is equal to VEnd for the previous road segment, or zero if this is the first segment of a road.

How Distance Is Computed

Distance is computed between two nodes that define a road, or the distance between two points of a road string that connect the two nodes.

Therefore, when digitising roads with short segment lengths that are less than the deceleration distance, it is feasible that the calculated terminal speed (VEnd) is greater than the specified maximum speed for the road segment. This is a limitation of the methodology, which could be overcome by having a “look ahead” function to start slowing the truck down before reaching the start node of the road segment.

This potential over-speed can be compensated for by limiting the speed on the approach segment.

Defining Linear Model Parameters

To use the linear model parameters, select a haul truck item on the Scheduling Data Setup screen, activate the Performance tab, and select Linear.

Defining Rimpull and Retardation Model Settings

To use the rimpull and retardation model settings, select a haul truck item on the Scheduling Data Setup screen, activate the Performance tab, and select Rimpull and Retardation.

Configure Performance Settings

To define linear model parameters:

Display the Performance Settings screen.
If you are using the linear model, select Linear and enter values in the Model Settings group.
In Rel Effective Gradient (%), enter a value (%) for the relative gradient.
In Max Effective Gradient (%), enter a value (%) for the maximum effective gradient.
In Minimum Speed (km/h), enter a value (km/h) for the minimum truck speed.
In Speed Loaded (km/h) - Up(+), enter a value (km/h) for the uphill loaded truck speed.
In Speed Loaded (km/h) - Down(-), enter a value (km/h) for the downhill loaded truck speed.
In Speed Loaded (km/h) - Flat, enter a value (km/h) for the flat loaded truck speed.
In Speed Empty (km/h) - Up(+), enter a value (km/h) for the uphill empty truck speed.
In Speed Empty (km/h) - Down(-), enter a value (km/h) for the downhill empty truck speed.
In Speed Empty (km/h) - Flat, enter a value (km/h) for the flat empty truck speed.
In Stopping Distance (m), enter a value (m) for the truck stopping distance.

To define rimpull and retardation:

Display the Performance Settings screen.
If you are using the rimpull and retardation model, select Rimpull and Retardation and define the loaded and empty parameters in the Model Settings group.
In the Loaded grid, enter the following settings:
- Effective Gradient (%) – Enter a value (%) for an effective gradient when the truck is loaded.
- Speed (km/hr) – Enter a speed value (km/hr) for the loaded truck.
- Rimpull (kg x 1000) – Enter a rimpull value (kg x 1000) for a loaded truck.
In Stopping Distance (m), enter a value (m) for the truck stopping distance.
In Graph Type, select Speed vs Rimpull or Gradient vs Speed to change the type of graph displayed in the right-hand pane.

Note: You need to define all rimpull and retardation parameters before applying changes.