Guides

Best Practices to Mitigate Injuries and Fatalities from Rock Falls (PDF, 1971 KB, 2000)
This paper presents an overview of the most significant ground control hazards facing today's mineworkers, as well as best practices to reduce these risks.

A User's Guide for the Bplane, Bstepp, and Bwedge Computer Programs (PDF, 2108 KB, 2007-03)
This user's guide covers the operation of a suite of three computer programs - Bplane, Bstepp, and Bwedge. These programs can be used to evaluate the potential for plane shear, step-path, and wedge failures along the crest of a slope bench. The theoretical basis, application, and operation of these programs are described.

Measurement & analysis

Effects of Specimen Age on the Uniaxial Compressive Strength of Weak Coal Measure Rocks (PDF, 764 KB, 2008)
This paper presents the results of a NIOSH study to evaluate UCS changes occurring in a broad range of weak coal measure rocks over a one-year time span.

An Evaluation of Microseismic Activity Associated with Major Roof Falls in a Limestone Mine: a Case Study (PDF, 253 KB, 2007)
Roof falls are often preceded by a period of elevated microseismic activity, but not all periods of elevated activity result in a roof fall, nor do all roof falls occur after some amount of elevated activity. The objective of this study is to review periods of elevated microseismic activity and determine whether fracture activity rate can be used to anticipate the initiation of roof falls. The results show that limited success would have been achieved by the microseismic system as a roof fall alarm trigger. However, the trigger would have been successful at warning of the onset of elevated activity, allowing mine employees to respond appropriately.

Failure Characteristics of Roof Falls at an Underground Stone Mine in Southwestern Pennsylvania (PDF, 617 KB, 2001)
The location and time of 2,007 microseismic emissions from a limestone mine in southwestern Pennsylvania were compared with the development of mine faces and the characteristics of the mine layout. Based on analyses of these results, the occurrence of roof failure zones appears to be associated with certain characteristics of the mine plan.

Methods for Determining Roof Fall Risk in Underground Mines (PDF, 322 KB, 2007-11)
This paper discusses a method to determine the roof fall risk using a qualitative risk analysis technique.

Engineering controls

Design of Primary Roof Support Systems in U.S. Coal Mines Based on the Analysis of Roof Fall Rates (PDF, 588 KB, 2001-06)
A study is described where information was collected at 37 coal mine on roof falls, and other geotechnical, mining, geologic and roof bolting factors. A statistical analysis was conducted on the data with the roof fall rate being the outcome variable.

Evaluating Techniques for Monitoring Rock Falls and Slope Stability (PDF, 3017 KB, 2002)
Several remote-sensing technologies are being evaluated as tools to monitor slopes for hazards and to assess slope stability.

Ideas to Reduce Roof Fall Injuries (HTM, 1997)
A range of ideas to deal with reducing roof fall injuries from miners, mining safety professionals, and NIOSH research.

Personal Bolter Screen: Surface Control to Protect Underground Workers in Coal Mines (PDF, 297 KB, 2003-08)
The Personal Bolter Screen is simply standard wire mesh, produced in approximately 5-ft square sheets. The small sheets provide much of the same protection as traditional 13-16 ft wide wire mesh, but are much easier to handle, store, and install. The results of the trials conducted underground have been extremely positive.

Roof Screening for Underground Coal Mines: Recent Developments (PDF, 1421 KB, 2007)
This paper describes some successful techniques and machine modifications that were evaluated for ergonomic considerations and are being used in productive mines to assist with roof screen installation.

Administrative controls

How to Prevent People from Going Under Unsupported Roof (HTM, 2002)
Ground fall accidents have been the leading cause of fatalities in the underground coal mining industry for many years. Statistics from MSHA indicate that approximately one-quarter of the victims of these fatal accidents were in an area where no devices had been installed to support the mine's roof.

Technique to Assess Hazards in Underground Stone Mines: the Roof Fall Risk Index (RFRI) (PDF, 2535 KB, 2007)
A roof-fall hazard-assessment technique was developed based on engineering judgment acquired from extensive underground stone mine experience and on examination of the related literature. This technique utilizes observational processes to determine roof fall likelihood. Case-study scenarios offer a realistic picture of model implementation.

Equipment

Roof Hazard Alert Devices (HTM, 2001-06)
Miners have been known to unknowingly venture beyond the last row of roof bolts in underground coal mines. To help discourage miners from going under unsupported mine roof, NIOSH researchers have developed two flashing light roof hazard alert devices that direct a miners attention to a written message, warning the miner to avoid the hazard beyond the device.

Training exercises

Bulls Double Header: Too Much Unsupported Roof
You work at a mine that has approval to make 34 ft cuts using a remote controlled continuous miner. The roof bolting machine has broken down. The continuous miner has just been refitted with a new cutting head and bits that cut the coal much faster. The two roof bolter operators have been having a hard time keeping up with Bull, the continuous miner operator. At the face of #4 entry, Bull makes a 40 ft extended cut, trams back from the face, and then turns the miner and cuts the left-hand crosscut all the way through to the #3 entry. When the roof bolter operators discover Bull's "double header", they get the section foreman, and then try to plan a safe way to bolt this large area of unsupported roof. Shortly after they complete their assessment and plan of attack, a large roof fall occurs. Now the face crew must decide how to safely clean up the fall while advancing roof support.

Bernie's Feeder Accident
A feeder in the reclaim tunnel under the product pile at a phosphate ore processing plant has failed and fallen on the belt conveyor. The belt is stopped. You and two workers are moving timbers to prop and jack the failed feeder so it can be repaired. Bernie, one of your co-workers is tired. He places himself in a dangerous position. He is hurt. You must provide first aid and remove him from the tunnel.

Pete's Predicament: Unsupported Roof
The preshift examination has been completed. The entire section has been rock dusted. John and Eddy advance the miner to the face of the #3 entry and begin cutting coal. Pete is standing near the right rib watching the mining machine to observe its new water spray system. A shuttle car comes up close to the right rib. After watching the miner cut coal for less than a minute, Pete starts to get worried that he is in danger of being squeezed between the continuous miner and the rib. He steps back around the comer into the right-hand crosscut which is rock dusted. Then he notices that half of the crosscut is unbolted and the top is dribbling small pieces of shale! Pete cannot escape into the #3 entry because the miner tailboom and shuttle car block that route. He sees that the far end of the crosscut is bolted. Pete must decide what to do to escape and to warn Eddy, John, and the shuttle car operator who are inby an unbolted crosscut. After Pete and Eddy escape, John must decide whether to abandon the mining machine and make a run for safety or to stay in the miner operator compartment under the canopy.

Roof Fall Entrapment
A group of miners are extracting pillars in an unsafe manner. There is only one escapeway from the area where they are working. Earlier roof falls have blocked the other escapeways. The top is bad in the one entry being used for the haul road. The posts and crossbars that support it at the intersection of a crosscut begin to sag so much that the shuttle car you are driving can't come out from the face. The foreman yells at you to tell the miners to get out. But it is too late! As you are about to come out, there is a large roof fall that completely blocks the one escapeway. You and the other miners are lucky. No one is hurt. But now you must decide what to do.

Roof Fall Entrapment: Eyewitness Account by Dave Garry
Dave, a miner helper, tells about witnessing a roof fall that covered a continuous mining machine. He discusses efforts that were made inby supports to rescue the trapped, but unharmed operator and recognizes that danger could have been minimized by installing temporary supports before continuing rescue.

Roof Fall Entrapment: Eyewitness Account by Dave Murone
Dave tells about the experience of having to recover the body of a friend who was killed by a roof fall. The individual who was killed was inby supports at the time of the accident. Dave speculates on why his friend was under unsupported top and discusses the effect that witnessing this accident had on him.

Roof Fall Entrapment: Eyewitness Account by Larry Strayer
This video consists of an interview with a miner who tells about a fall that occurred while he and another miner were attempting to bar down top just inby the last row of supports.

Roof Support in a Primary Escapeway
On a recent run of the escapeways, the section boss notices that the brow of a high fall area has begun to deteriorate. On this particular day, the face boss asks the miner operator and helper to follow the escapeway out from the face and take down any loose top at the high fall area. After correcting this problem, the workers encounter another hazardous roof condition nearby. This involves deterioration of the immediate roof around the bolt heads as a result of moisture in the mine air.

Sammy's Loose Roof Decisions
During your routine survey work as a transit-man, you observed in recent weeks that an idle section in 2 North mains, about 3 miles from the portal, has been experiencing serious roof problems. You were told by one of the mine engineers that the problems are due to the sudden presence of slips in the roof running in the direction of mining. Several falls and significant downtime have forced the company to reconsider the development of 2 North. On this particular day, the general superintendent informs you and Sammy that the company decided to reactivate the idled section beginning next shift. You are to enter the mine and set sights in 2 North to re-orient all the entries by 45 degrees to the east before the regular daylight crew arrives. You are beginning your work when you notice a section of top lower than the surrounding area. You must decide whether this is a problem that can wait or if it should be taken care of immediately.

Unsupported Roof Rescue
You are the pinner operator. Your helper, Marvin, goes under unsupported roof. As you yell to him to get back, there is a roof fall. It catches Marvin's legs. Marvin is lying face down and screaming. The roof is dribbling across the whole entry. You have to figure out how to rescue and help Marvin without getting yourself or other miners injured.

Videos

Make it Safer with Roof Screen
Using extensive underground footage, this7-minute video shows how well screens keep loose rock from falling in difficult roof conditions. Techniques for installing screens for both outside-controlled and walk-through roof bolting machines are shown. The video also provides safe handling tips, best practices, and information about machine technology that can greatly improve material handling.

Rock Falls - Preventing Rock Fall Injuries in Underground Mines
This video teaches the importance of proper roof scaling in underground mining to avoid injury and improve work conditions.