By Ch.Jayaramakrishna, Project Officer, PK.OC

HAUL ROAD

Introduction:

• The roads which are prepared for plying of heavy earth moving equipment for carrying of coal and Overburden in Opencast Mines are called Haul Roads.

Design of the Haul Road• To maintain good health of the

equipment, the haul road should be designed considering the specification of the equipment like

Width HeightWeightWheel Base.Type of Braking System.Steering ability.Retarded performance.Speed range on grades etc.,

Advantages of good Haul Road

• A good haul road will result in numerous advantages like:

Reduced cost of maintenance of equipment

Reduced breakdown of vehicles and their better availability

Reduction in fuel consumption

Achieving better safety standards

Improved working environment and ergonomics for the operators

Increase in tyre life

Cont..

Con..

• A Good Haul Road will:

Increase in production by 30 %.

Reduced fuel consumption by 30 %.

Width of Haul Road:

No road shall be of width less than 3 times the width of the largest dumper plying on the road plus 5 Mts, if the movement is on single haul road.

– Width of 35T Dumpers: 4.4 mtrs– Width of 85T Dumpers: 5.8 mtrs– Width of 100T Dumpers: 6.6 mtrs

Thus the width of the haul roadFor 100 T Dumper = 24.8 Mts. ( 6.6 X 3 + 5)For 85 T Dumper = 22.4 Mts. ( 5.8 X 3 + 5)For 35 T Dumper = 18.2 Mts. ( 4.4 X 3 + 5)

If the road is provided for single traffic of vehicles with a strong road divider at the centre, the width shall not be less than two times the width of the largest dumper plying on the road plus 3 Mts.

Characteristics of Haul Road as per Mine Statute

Gradient: At any place on the haul road – not more than

1 in 16. In case of small ramps over small stretches, a

gradient upto 1 in 10 may be permitted.

Visibility: All corners and bends in roads shall have a clear

view of distance not less than three times the braking distance of the largest HEMM working at 40 KMPH.

Con..

Con..

Embankment and Bund:

Where any road exists above level of surrounding area, it shall be provided with strong parapet wall / embankment with the following dimensions.

Width at top not less than 1 Mt.

Width at bottom not less than 2.5 Mts.

The height of the bund lot less than the diameter of the tyre of largest vehicle plying on the road.

Con..

Haul road Lighting: Required standard of illumination shall be

0.5 to 3.0 Lux (Horizontal).

Traffic Signs: Traffic Signs may be speed limit signs,

stop signs, curving and intersection warning signs which shall be provided at required locations all along the haul roads.

Parameters governing good haul roadConstruction of good haul road depends

on good planning and design of haul road.

The parameters that govern in making a good haul road are

Base Material.Surface Material.Site distance.Gradient.Haul Road width, road side berms and guard rails.Traffic rules and signs.

Con..

Drainage provisions, slope above and below haul roads.

Haul Road lighting

SUPER ELEVATION

• The amount by which the outer edge of the road has to be raised is known as super elevation. It is expressed in Mtr/ Mtr.

• Here tan = Centrifugal force / truck weight = mv2 / r . mg

= v2 /gr

Here, it is noted that angle is independent of the weight of the truck.

• Vehicles negotiating curves are forced radially, outward by Centrifugal force. Counter acting forces are the frictions between the tyres and the road surface, and the vehicle weight component due to the super elevation.

• The basic formula is • R min = V2 min / 127(e+f) where • V min = minimum design speed in KM/H • R min = minimum curve radius in Mtrs• e = rate of super elevation• f = co-efficient of lateral friction.

SUPER ELEVATION

Forces acting on the truck while moving

Centrifugal Force

weightResultant

The truck moving along the curve is subjected to the following two forces as shown in the figure

Why Super Elevation?

• If the road is made level the resultant force will be inclined at an angle with the vertical and thus the reaction at inner and outer track will not be the same.

• At certain speed of the truck the reaction at inner track will become negative leading to toppling of the truck.

• To counter balance this effect and to maintain the equilibrium of the machine the surface of the haulage road has to be made perpendicular to the resultant reaction by raising the outer edge of the road.

• The amount by which the outer edge has to be raised is known as super elevation.

Con..• Effect of motion of the truck along a curved

road is skidding away.

• This is counter balanced by the frictional force between the tyres and roads which is fully effective when the reaction at inner and outer tracks is equal.

• This is restored by proper super elevation.

• When the centrifugal force is balanced by the vehicle weight component, the slide friction factor would be zero.

Recommended Max super elevation at various speeds

Radius of curves in

MtsSpeed in Km / hr

25 40 60

15 0.04 0.04 0.04

30 0.04 0.04 0.05

45 0.04 0.04 0.05

75 0.04 0.05 0.06

Occurrence of Incidents and Accidents

With changing scenario and introduction of higher capacity equipment, the no. of incidents and accidents has taken place due to

1. Head on collision of dumper on haul road due to poor clear view.

2. Front and rear collision of dumpers on haul road

3. Inadvertent movement of steering wheel along with tyre while maintenance of dumper where engine is “ON”

Con. 4. Due to work person crossing the blind

space in and around.

5. Dumper getting-off haul road due to inadequate parapet wall / embankment.

6. During reversal of dumper movement.

Traffic Rules and Procedures Introduction:

The following rules are designed for safe operation of vehicles in and around the mine. The operators of vehicles shall observe these rules and any other special instructions given by the Mine Manager. The Mine Manager and officials appointed by him shall ensure that all persons in the mine comply with these rules.

Rule-1 Procedures: Authorized persons shall only drive or operate the

vehicles as assigned by the Mine Manager.A private vehicle shall not be driven in the mine

premises unless authorized by the Mine Manager. A driver working temporarily shall request and

receive permission to enter the mine premises from mine Manager prior to driving a vehicle in the mine premises.

Rule-2 Speed Limits:Permanent or temporary speed limit set by the

mine Manager for any area of the mine shall be adhered to.

Where visibility or road conditions are poor, the driver shall reduce the speed of the vehicle to maintain effective control.

Rule-3: Right of Way: All drivers shall give way to emergency vehicles. Vehicles used for grading, rolling, watering and

repairing of roads shall have right of way over all vehicles.

Light vehicles shall give way to all HEMM

Rule-4: Parking and Standing: A driver shall not park vehicle in a position that will

endanger other traffic, or opposite to another vehicle on a haul road.

Shall not park within 30 Mts of the working area of mobile equipment.

Shall not park within 30 Mts of swing radius of any shovel.

While parking shall chock the vehicles if parked on a slope.

Rule-5: General:

Vehicles shall not be driven over electric cables, air hoses or water lines unless these are properly protected.

Seat belts shall be provided and shall be worn by operators at all times while operating the vehicles.

Transport of persons in the vehicles is not allowed.

The drivers shall sound one blast of horn before moving off from parked position.

No spillage on vehicles during transportation is allowed.

The vehicles shall be correctly illuminated during hours of darkness.

Shall observe adequate clearance particularly when reversing, parking, passing other vehicles.

Rule-6: Overtaking:

Overtaking any other Vehicle with caution may be done provided:

The speed limit is not exceeded.There is sufficient visibility of the road ahead.The vehicles are clear of any road intersection or

junction.

Rule-7: Signs:All Traffic signs are to be obeyed.Warning signs are to be noted at all times.Temporary signs shall be removed as soon as

possible after need for them ceases to exist.

Rule-8: Mechanical Condition of vehicles: The Driver of each heavy vehicle shall make daily examination

of the vehicle for safe operation Any defect observed in the vehicle as well as damage to the

vehicle shall be reported forthwith to the superiors.

Rule-9: Definitions: The following vehicles are classified as Heavy vehicles: Haul trucks ANFO trucks Fuel and water trucks Wheel dozers and Loaders Buses The following vehicles are classified as Light vehicles: Jeeps / Maruthi Gypsy's Station wagons

Permission Conditions at OC-II Section

1. The Height of benches in Overburden ,Coal shall not be more than the height of the machine used for digging, Excavation or removal.

2. As a final operation, the width of the bench may be reduced to not less than 3 mtrs.