Property

Description

Truck

This retrieves and sets the SimpleTruck Object associated with the current set of calculations. The object will be described in full below.

HaulRoute

This retrieves and sets the HaulRoute Object associated with the current set of calculations. The object will be described in full below.

HaltOnErrors

Use this Boolean property to signify whether the calculation object should show message boxes in the event of an error.

Note: By default, this value is set to TRUE.

You can use GetLastError to retrieve the last error, regardless of the settings of HaltOnErrors.

GetLastError

This function returns the most recent error encountered by the travel time calculations.

If the last calculation did not encounter any errors, then this value will be blank (Empty). This means that you can check GetLastError to test for whether the calculation was successful or not.

StartingVelocity

This retrieves and sets the StartingVelocity of the Haul Route. The starting velocity is the velocity at the start of the first haul segment. (All other haul segments use the final velocity of the preceding segment as their initial velocity). The starting velocity will initially be 0 km/h (0 mph). This value is specified as a double.

MinimumAcceleration

This retrieves and sets the MinimumAcceleration of the Haul Route. At low speeds, the retard forces available are very high and therefore the deceleration rates may be very high. It is often not practical for a large, heavy vehicle to decelerate at the rate determined from the retard curve. An operator will not normally apply the retarder to the maximum possible, rather they will decelerate at a rate that is comfortable to them. For this reason, a limit can be applied to the deceleration rate.

TravelTime allows users to specifiy Maximum Allowable Deceleration for both loaded and unloaded trucks. This allows the user to better simulate the effect of driver caution when travelling under load down steep slopes. The Maximum Allowable Deceleration will initially be set to -1.5 km/h/s (-3.1 mph/s) for both loaded and unloaded. This is the highest deceleration rate that will be allowed for a truck under braking. This value is specified as a double.

MaximumAcceleration

This retrieves and sets the MaximumAcceleration of the Haul Route. At low speeds, the rimpull forces available are very high and therefore the acceleration rates may be very high. It is often not practical for a large, heavy vehicle to accelerate at the rate determined from the retard curve. An operator will not normally put their foot flat to the floor, rather they will accelerate at a rate that is comfortable to them. For this reason, a limit can be applied to the acceleration rate.

This is the upper limit of acceleration in km/h/s or miles/h/s. This value must be in the range 0 to 35.28 km/h/s. The maximum allowable acceleration will initially be set to 1.5 km/h/s (3.1 mph/s). This value is specified as a double.

MaximumTraction

This retrieves and sets the MaximumTraction of the Haul Route. This value is 0.0 by default and is specified as a double.

IncrementalVelocity

This retrieves and sets the IncrementalVelocity of the Haul Route. All calculations for vehicle motion are based on increments of velocity. The smaller this value, the greater the accuracy of the travel time calculation and the longer it takes for the procedure to run. The initial value for incremental velocity is 1.0 km/h (0.6 mph). This value is specified as a double.

CoefficientOfTraction

This retrieves and sets the CoefficientOfTraction of the Haul Route. The coefficient of traction is a factor applied to the mass of the vehicle to determine the proportion of rimpull that can be used to move the vehicle. It is also used to determine the braking distance when retard data is available. Use of the coefficient of traction is based on the following equation:

UseableRimpull – CoefficientOfTraction x WeightOnDrivingAxle

The coefficient of traction cannot be greater than 1.0. The initial value for the coefficient of traction is 0.36. This value is specified as a double.

BrakingRelianceOnTraction

This retrieves and sets the BrakingRelianceOnTraction of the Haul Route. The braking reliance on traction represents the reliance on the traction coefficient to slow the truck when it is braking. It is expressed as a percentage. If it is less than 100%, the distance required to brake will be proportionally increased. This factor represents, on average, how close the operators of the truck will approach the critical limit, where the available traction for braking is less than that required (ie. where skidding occurs). The initial braking reliance on traction is 70%. This value is specified as a double.

EmptyTruckWeight

This retrieves and sets the EmptyTruckWeight of the Haul Route. This value is 150000.0 by default and is specified as a double.

FullTruckWeight

This retrieves and sets the FullTruckWeight of the Haul Route. This value is 370000.0 by default and is specified as a double.

RetarderSpeedLimitsUse

This retrieves and sets the RetarderSpeedLimitsUse of the Haul Route. Where retard speed limits are applied, TravelTime calculates the maximum speed at which the retarder can just maintain the truck at a constant speed. This limit is only applied on downhill sections where the grade is greater than rolling resistance, ie. when there is a net downhill force on the truck. TravelTime determines at what speed the retarder forces and the downhill forces cancel out. Retarder forces are derived from the retard curve associated with the truck. If the maximum speed for this section of the haul cycle is greater than the speed calculated from the retard data, TravelTime will automatically limit the truck to the calculated speed.

The use of retarder speed limits may be set to:

This option is initially set to ALWAYS (0).

RetarderSpeedLimitsMaximum

This retrieves and sets the RetarderSpeedLimitsMaximum of the Haul Route. On sections where retarder speed limits are applied the maximum speed limits can be further reduced. Heat is generated from the use of a retarder. The amount of heat generated is proportional to the retard force applied. A truck's heat exchanger is rarely big enough to dissipate the heat generated from maximum usage over extended downhill hauls. This factor allows you to limit the use of retarder force, to allow for heat dissipation. In general, the longer the downhill segments, the lower the factor should be. The initial value for the maximum use of retarder force is 70%. This value is specified as a double.

ActualPayloadForTruck

This retrieves and sets the ActualPayloadForTruck of the Haul Route. This value defaults to 0 which means that the override is disabled. This value is specified as a double.

FinalVelocityForTruck

This retrieves the FinalVelocityForTruck of the Haul Route. This value defaults to 0 prior to calculation and requires Calculate() to be called before the calculated value will be available. This value is specified as a double.