- If you have a haul road design standard, please share.
- Do all your haul roads have berms?
- Do they differentiate between safety berms and other berms (ie: road delineation berms, etc)?
- Does any of your standards include cut outs and road maintenance requirements? Please provide if applicable.
Our standard is 1 ½ width of a loader bucket on the property( only for single lane traffic)
We have road berms, rule of thumb is the berm has to be half the height of the largest tire traveling on the road.
We do not different berms for different locations. All berms onsite are the same.
We don’t include cut outs for our site. Road maintenance is a constant due to access road to pit is up against a mountain. Rock falling down all the time.
30m Road Width
8% max ramp grade (this is a target, we've increased to 10% depending on the situation, but likely temporary in nature)
All haul roads have safety berms. Typically we only see "delineation" berms on the dump to separate the dump working area from the washrooms. Also found separating a maintenance area from a haulage area (ie. Shovel pads).
In terms of other considerations ("cut outs" for example), when we're designing intersections we do our best to align traffic so that the haul trucks come perpendicular to the intersection allowing better line of sight. Again not formalized, just something we aim for.
To expand on the “cut outs” (bullet point #4 below), we install them in sensible drainage areas at irregular intervals. I am assuming that they are referring to “rock slots” in berms for drainage.
All our haul roads have berms, they are built half height of our biggest haul truck tire, we use 789’s.
When using wiggle wagons, we build berms to half height of that tire.
777 same as above.
Road Widths
All mine roads are Right hand drive with minimum running surface width of 35 metres and a maximum 2% centerline crown.
35-metre specification is based on the width of the widest truck in use in the mine. Running surface width for single lane access must be twice the width of the widest vehicle or 18
metres. All single lane roads must be identified with signage.
Super-elevating road curves will be done whenever possible to maintain truck efficiencies and minimize spill. Ditches alongside haul roads are sloped at 2H:1V
Road Grades
Permanent haul-roads will be graded to no steeper than 5% unless mine development dictates
otherwise to ensure extraction of the resource. In situations where permanent ramps will exceed 5%
but do not exceed 8%, adequate signage and run-out lanes will be installed.
Roads that are built to grades exceeding 5% can only be used for a defined temporary period and subject to the following design criteria:
• a temporary haul road ramp is defined as a ramp travelled by mine haul trucks that is
designed at a maximum grade of 8% and a maximum vertical elevation change of 30 metres.
The ramp is designed and planned to be in place for a specified period of time which will be
agreed upon by Mine Engineering and Mine Operations
• a temporary haul road ramp must not exceed a vertical distance of 30 metres.
• a temporary haul road may exceed 5% grade but not exceed 8% along any portion of its
length.
• a temporary haul road exceeding 5% but not exceeding 8% grade must have signage in
place that identifies the ramp as being up to 8% grade.
• the temporary ramp must comply with berm requirements as stipulated in the Alberta OH&S
Code Section 539(3).
• any temporary haul road exceeding 5% grade must incorporate at least one emergency
escape route at the bottom of its slope.
• the emergency escape route must be a minimum of 150 metres in length measured from entrance
of the emergency escape route to the impact berm.
• at the end of the emergency escape route, an impact berm across its full width shall be
placed using competent material that is piled to one-half the height of the largest haul truck
tire in use on the temporary ramp.
• the emergency escape route must be of a level grade, as practically close to 0% as possible.
• where road systems allow it, the emergency escape route must be adequately marked with
signage at its entrance.
• no parking or stopping on a temporary ramp shall be permitted within 50 metres of an
entrance to an emergency escape route.
• where road systems allow it, the emergency escape route must be clearly marked and
delineated along its entire length.
• the emergency escape shall be established so as to be free of any physical obstructions
such as windrows or equipment, at all times.
• the emergency escape route shall be maintained so that it is passable at all times for
equipment requiring its use in an emergency. This includes maintaining adequate drainage
and clearing of snow.
• where road systems allow, controls must be implemented to prevent the travel on or across
the emergency escape route throughout its full distance.
• any temporary haul road ramp that exceeds a 5% grade shall be surveyed and its location be
displayed on mine plans posted for viewing.
Note: Any ramp that does not meet the above criteria must be designed and approved
by Mine Technical Services.
Road Construction Specifications
• a typical mine haul road cross section can be broadly subdivided into Subgrade (road base), Subbase, and Base Course and Surface course.
• the Subgrade is the existing ground surface on which the road is built, and Subbase, Base Course and Surface Course are layers of good quality granular fills that will be successively placed above the Subgrade.
• if the Subgrade lacks sufficient bearing capacity to support the applied heavy hauler loads, it will be improved through suitable measures such as sub- excavation of soft material, compaction and or bridging over with suitable Subgrade fill. Geosynthetic products can also be used outside the mine pit for subgrade separation and mechanical subgrade reinforcement.
• the average thickness of the granular road fill is about 2.5 metres and it will be placed over a 2-metre thick competent in-situ or compacted road base.
Only where required by OHSC – otherwise delineators berms are used to defined the width of the haul road. Part 36, section 539(3) of the Alberta OHS Code: Berms must be used on roads or lifts that expose mobile equipment to a vertical fall of 3 metres or more.
Berm Specifications
• berm height – 1/2 height of largest tire using the haul road
• berms are pulled back 30 metres from intersection
• berms are to be constructed from suitable material i.e. no large lumps or snow
• side slopes of berms are 3H:1V
In situations where Part 36, section 539(3) does not apply, or where there is no risk of mobile equipment collision or potential for rollover, traffic can be controlled by a “working berm” or delineation berm. Working berms are short-term earthen berms of at least 0.3 metres of height to prevent mobile equipment from entering an area being excavated. Delineation berms are smaller berms that act to define the sides of the haul road or to guide mobile equipment to a specific passage, direction or crossing route. Our internal policy and procedure manual allows the supervisor to determine the suitable dimensions of the delineation berm, as well as to choose whether an alternate manner of delineation is established, such as manual systems, flagging, stakes, cones, reflective devices, etc., or any combination of these with earthen material. Often, a grader windrow is sufficient to satisfy road delineation requirements. Another benefit of haul road delineation is that is limits the areal extent to which road maintenance activities must be conducted, saving time and resources.
Berm breaks – driven by road profile. Part 36, section 539(3)b of the Alberta OHS Code states “Any breaks in the berm of a surface haul road must not be greater than the width of the smallest haul truck in regular service on that road”. Berm breaks, cut outs or slot cuts are established by mine supervision as required for access and drainage purposes.