Spreadsheet: 732722d1621184709-if-function-with-and-imbedded-field-compliance-follow-up-sheet-v1
Sheet: 12  months

ITA Guidelines for good Occupational Health and Safety practice
in tunnel construction
 | Compliance field inspection follow-up
OHS Aspects | Requirements | Date of assessment | Score achived | Date of re assessment | Scrore achived | Variation | Date of re assessment | Scrore achived | Variation | Date of re assessment | Scrore achived | Variation | Date of re assessment | Scrore achived | Variation | Date of re assessment | Scrore achived | Variation | Date of re assessment | Scrore achived | Variation | Date of re assessment | Scrore achived | Variation | Date of re assessment | Scrore achived | Variation | Date of re assessment | Scrore achived | Variation | Date of re assessment | Scrore achived | Variation
3 | Emergency Plans
3.1 | These should be prepared for foreseeable emergencies which could arise during the tunnelling operations. Such emergencies could include:
 | Serious and multiple accidents including personal injuries
 | Plant or other power failures (especially in compressed air tunnels).
 | Ground collapse at the tunnel face.
 | Failure of temporary or permanent ground support some distance behind the excavated face.
 | Substantial water or mud inflow leading to floodin
 | An explosion, perhaps caused by a concentration of a naturally occurring gas such as methane.
 | [NAME] deficiency.
 | Fire in the shaft or tunnel.
 | Misfires in the use of explosives.
 | Transport accident
3.2 | In contingency planning, particular attention should be given to:
 | Means of escape in an emergency situation. (Specific escape routes should be marked by signs).
 | The maintenance of essential power, firefighting, inundation pumping, atmospheric monitoring, lighting and communications systems during an emergency.
 | Clear labelling of power supplies and switches – including emergency lighting, pumping, ventilation and signalling.
 | Ensuring a reliable and clear means of communication from, to and within the tunnel even in the event of power failure
3.3 | On every site there should be a clearly defined chain of authority for emergency action. Contingency and emergency plans should be made known to all the workforce.
3.4 | The authority for directing emergency action should rest with one postholder - for example the site manager or other nominated senior site person.
3.5 | The first priority in any emergency action is to minimise the risk to persons working underground. To achieve this objective it is necessary to know the number of persons working within the underground system at any one time.
3.6 | The site management should discuss the handling of possible emergencies with the public rescue services. Such discussions should be commenced before the construction stage of the project begins. There is a need for on-site familiarisation of the emergency fire and rescue services.
3.7 | It shall be the duty of every person on site to report any circumstances that could lead to an emergency, thereby enabling effective action to be taken at the earliest moment.
3.8 | Contingency planning should ensure that essential equipment and personnel for major emergencies (for example rescue equipment, fire fighting equipment, suitable breathing apparatus, stretchers, temporary lighting etc) can be obtained at short notice if they are not already on site.
3.9 | If the underground works are complex, a clear, durable and up-to-date diagram
4 | Personal Safety Equipment
4.1 | General
4.1.2 | Personal safety equipment should be provided, e.g. hard hats, high visibility overalls, adequate foot protection, hearing protection, eye protection, respiratory protection.
4.1.3 | Means of identifying and accounting for personnel in an emergency situation.
4.2 | Equipment to be provided
4.2.1 | Hard hats for head protection should be issued to every person entering the works and the wearing of hard hats should be made compulsory.
4.2.2 | During shotcreting operations eye protection should be worn.
4.2.3 | Where noise levels exceed the threshold limits (see Section 11) and levels cannot be reduced then hearing protection should be used, e.g. ear muffs or ear plugs.
4.2.4 | Under all conditions where dust levels are high (see Section 11) or where specified by local statutory requirements, appropriate respiratory protective equipment should be used, e.g. during shotcreting operations.
4.2.5 | All underground workers should be provided with safety boots of acceptable quality. Such boots should be suitable for both dry and wet conditions.
4.2.6 | Hand protection in the form of gloves should be provided where the type of work requires some form of protection. A general purpose type of glove may be adequate for most types of work but special conditions would require special gloves, e.g. special gloves required for welding operations.
4.2.7 | High visibility clothing including waterproof clothing, should be provided and used by all workers underground.
4.2.8 | [NAME] lamps should be issued to all persons entering the underground works except where adequate lighting and emergency lighting systems are installed. The minimum operating time should be 12 hours.
4.2.9 | Recharging facilities should be provided.
4.2.10 | A register of each cap lamp issued should be kept in which the condition of lamps is recorded.
4.2.11 | Self-rescuers should be issued to each worker underground. They should always be carried by the worker or in close proximity to his working place.
4.2.12 | Where necessary, safety harnesses should be provided and used for persons
5 | Underground Traffic
5.1 | Pedestrians
5.1.1 | All pedestrians in the tunnel should be equipped with high visibility protective clothing incorporating reflective stripes on body, arms and legs.
5.1.2 | The tunnel should be equipped along its full length with adequate lighting and emergency lighting (the latter could include the use of cap lamps).
5.1.3 | Pedestrians should only be allowed to walk on one side of the tunnel. For this purpose, suitable signs should be erected at the tunnel portal and in the tunnel, indicating the side where pedestrians will be allowed. All signs should be reflective or illuminated
5.1.4 | A pedestrian walkway of adequate width and with adequate overhead clearance should be provided. In choosing the side of tunnel where the walkway is to be provided, the type of equipment in use should be considered.
5.1.5 | Each pedestrian or group of pedestrians should carry a flashing or steady light depending on local practice. Pedestrians must be seen as well as being able to see. This requirement may be dispensed with where no moving plant is in use.
5.1.6 | An access control system should be operated to account for all personnel underground and to restrict access to the underground workings to authorised persons only.
5.1.7 | No person should be alone at any work site underground. If this precaution cannot be observed, an adequate alarm system must be provided.
5.1.8 | There should be procedures for the handover of safety critical information from the outgoing to the incoming shift. A written record of this information should be maintained.
5.1.9 | Visitor groups should only enter the tunnel when they are not endangered by operation and traffic. Visits shall be organised accordingly.
5.2 | Transport Infrastructure
5.2.1 | Safety aspects, including adequate separation between pedestrians and vehicular traffic, should be considered in the layout of the transport infrastructure.
5.2.2 | Roadways and rail tracks shall be carefully laid out and properly maintained. Vehicles and rolling stock shall be chosen according to the gradients to be traversed.
5.2.3 | Where there is a risk that a runaway vehicle (road or rail) could unintentionally enter a workplace, means of diverting or stopping that vehicle should be provided.
5.3 | Road and Rail vehicles
5.3.1 | [NAME] and free steered vehicles for use underground should be designed, assembled and equipped, so that the operator can fully observe the danger zone of his vehicle in both directions. Where the driver cannot fully observe the danger zone, a CCTV camera
5.3.2 | All rail or free steered vehicles underground should be equipped with an audible warning signal.
5.3.3 | Road and rail vehicles should be provided with two white lights in the direction of travel and with red rear lights. When the direction of travel is reversed, the colour of lights should be reversed automatically.
5.3.4 | Special transport units (explosives and emergency units) should be equipped with a special signal (revolving orange lights for example).
5.3.5 | All vehicles on the surface should be similarly lit at night.
5.3.6 | Vehicles should be capable of stopping within the sight distance of the operator.
5.3.7 | Braking systems should be properly maintained.
5.3.13 | All vehicles should be properly maintained
5.4 | Transport of personnel
5.4.1 | Passengers should be transported within specially equipped enclosed vehicles.
6 | Mouvements in shafts
6.1 | Ladders
6.1.1 | Rest levels large enough for at least two persons should be provided at intervals not exceeding 8 metres.
6.1.2 | Ladders should be inclined and secured. They should be located away from other activities.
 | Persons operating mechanical hoists should be competent and duly authorised in writing to operate the equipment. Such authorisation should be kept in a safe place and a copy thereof displayed in the engine room.
 | Persons entering or leaving a hoist cage should do so under supervision.
 | If ladders are vertical they should be provided with safety cages.
 | If the shaft is used for movement of materials and spoil, this activity should be physically separated from ladders used by personnel. In narrow shafts where this cannot be achieved by means of a partition, the simultaneous movement of personnel and materials shall be prohibited
6.2 | Mechanical hoists, etc.
6.2.4 | There shall be alternative means of emergency escape from a shaft This shall be either by the provision of an emergency hoist which is supplied by a power source separate from that of the main hoist, or by the provision of ladders.
6.2.8 | Properly designed barriers to prevent vehicles, plant, materials or persons falling down the shaft should be erected around the top of the shaft.
6.2.9 | The area around the shaft should be fenced off on all sides and no storing or stacking of materials should be permitted within the fenceline. The size of the area on each side should be commensurate with the length of the largest item normally transported in the cage.
6.5.4 | Persons should only be raised or lowered in a purpose-built cage.
7 | Ventilation
7.1 | General
7.1.1 | A purpose-built forcing, exhausting or circulation ventilation system should be employed, depending on the contaminants which have to be rendered harmless.
7.1.2 | The concentration of oxygen, dust, toxic or potentially explosive fumes or harmful gases in the tunnel atmosphere should be routinely monitored and steps taken as necessary to ensure contaminant levels do not exceed those laid down by national legislation or guidance. Where a specific work activity known to generate significant contamination, such as welding, is being carried out, local monitoring should be undertaken.
7.1.3 | As a guide, the quantity of air supplied or extracted from the face should be such that the     average flow in the full cross section of the tunnel or shaft should be between 0,3 m/s and 2m/s at all times.
7.1.4 | In the absence of national legislation or guidance, legislation or guidance from another nation giving contaminant exposure levels should be selected as the base standard. Records of all routine monitoring should be maintained.
7.1.5 | Minimum quantity of air for personnel to be 1,5m3 per minute per man and 4m3 per minute per kW rated power for diesel machines. Additional air may be required for cooling purposes.
7.1.6 | Ventilation air entering a tunnel should be free from dust, smoke or other impurity.
7.1.7 | Ventilation should be such that in every underground working area, healthy conditions exist and fumes or gases shall be diluted to the extent that they are rendered harmless. A minimum oxygen concentration of 19% should be maintained at all times when persons are at work underground.
7.1.8 | The wet globe bulb temperature should not exceed 27oC. Ventilation can be used as a means of removing excess heat from the workings.
7.1.9 | To minimise dust generation, wet drilling techniques should be used in a tunnel in preference to drilling machines fitted with appropriate dust collection equipment. Other machines and processes creating dust should be fitted with appropriate dust suppression and collection equipment.
7.1.10 | Diesel-driven internal combustion machines should be fitted with particulate filters. These machines should be kept in good order and should not be left idling in the tunnel.
7.1.11 | In a tunnel with risk of potentially explosive atmosphere, safety critical equipment such as fire fighting equipment, pumping equipment, ventilation equipment, communications and atmospheric monitoring equipment should be explosion protected as necessary so that it remains operational even when potentially explosive gases are present.
7.2 | Control of contamination/contaminants
7.2.1 | The air in tunnels should be continuously tested for oxygen concentration and the presence of toxic gases. Tests for dust levels should be conducted at regular intervals whilst work is in progress.
7.2.2 | Dust levels in working areas should be maintained within national limiting values of acceptable dust concentrations. In the absence of national limits those from another country should be adopted.
7.2.3 | Dates, locations, conditions and results of tests should be recorded in a register.
7.3 | [NAME] deficiency
7.3.1 | Accidents have occurred when workers have entered unventilated tunnels and been overcome by a lack of oxygen in the air.
7.3.2 | It is imperative when entering underground works which have not been ventilated, to keep this risk in mind. When the oxygen content falls below 19% the works should be evacuated until ventilation is installed to restore the oxygen concentration to above 20%.
7.3.3 | If the old workings still have forced ventilation equipment, it is essential to adequately ventilate the works and test the return air flow before entering. No one should enter the works without being equipped with both CO and CO2 detectors and also an oxygen monitor
7.3.4 | During freezing operations where liquid nitrogen is being used, it is essential to continuously monitor the oxygen concentration in the air as the fracturing of a freezing pipe can increase the nitrogen content of the air and result in oxygen deficiency.
7.4 | Explosive atmospheres
7.4.1 | Checks using electronic atmospheric monitoring equipment should always be made to ensure that methane or other potentially explosive gas (e.g. Hydrogen) is not present in the ground to be traversed. Tests for potentially explosive gas should be specifically carried out before charging a face and after blasting.
7.4.2 | Where water (in which gas such as methane can be dissolved) or gas is expected, and probe boreholes have been drilled, tests should be carried out to identify and quantify any gas emission from the probe holes.
7.4.3 | If potentially explosive gas is detected further precautions including the use of explosion protected equipment, the use of special explosives, specific training for operators and supervisors etc should be considered.
7.4.4 | In potentially explosive atmospheric conditions, water cooled engines should be preferred because of lower surface temperatures than encountered in air cooled engines.
7.4.5 | If more than 20% of the lower explosive limit of the gas is detected in the tunnel atmosphere, all persons must be withdrawn, and all non-explosion protected electric and mechanical power switched off until a competent person has supervised the venting of the gas.
8 | Illumination
8.1.1 | The methods of lighting and levels of illumination in all parts of the tunnel and works should meet the requirements of national legislation or guidance, In the absence of national legislation or guidance, legislation from another nation or guidance such as this document should be selected as the base standard.
8.1.2 | All working areas should be constantly illuminated throughout their length to an intensity of 60 lux at floor level. Access ways should be constantly illuminated to an intensity of 10 lux at floor level.
8.1.3 | Adequate fixed lighting should be provided at all established stations, working faces, landing and loading places and other similar places in vertical and inclined shafts, tunnels and underground workings, and at night at all places on surfaces where work is being carried out.
8.1.4 | Where static machinery is used, the area should be illuminated so that the external moving parts of such machinery are clearly visible. The recommended level of illumination is 100 lux at the moving part.
8.1.5 | When work is taking place under potentially explosive atmospheric conditions, only an explosion protected light or lamp, approved by the appropriate Authority, shall be permitted underground.
8.1.6 | An emergency lighting system should be provided.
9 | Drilling
9.1 | General
9.1.1 | Appropriate precautions should be taken before drilling commences including barring and scaling the tunnel face and crown adjacent to the face, clearing the face and examining it and the muck pile for misfires. These should be dealt with in accordance with appropriate regulations.
9.1.2 | Mark round on tunnel face with material which can easily be seen and not removed, e.g. paint. Avoid drilling into existing sockets.
9.1.3 | Accurate marking, drilling and loading of the round will minimise shattering of surrounding rock
9.2 | Drilling machines
9.2.2 | Flush with water to prevent dust formation.
9.2.3 | Use well maintained equipment to reduce noise and vibration emissions
9.2.4 | Further reduce exposure to noise by using hearing protection during drilling.
9.2.5 | In many underground projects drilling is done by jumbos. These are normally hydraulic or compressed air driven from electric engines. [NAME] rigs should conform to EN 791 ([NAME] rigs, Safety) (see 22.1.9). Diesel power may be used for moving between drilling sites. Each power source gives rise to specific risks and in the design of drilling machines the matters set out below should be considered:
9.2.6 | Electric equipment should be designed and constructed to minimise the risk of electrocution to workers.
9.2.7 | Hydraulic and compressed air fittings should be properly fitted and maintained.
9.2.8 | Diesel engines should be of a low emission type and fitted with adequately designed and maintained particulate filters.
9.2.9 | Petrol engines should never be used underground.
9.2.10 | Suitable access to the various operating and maintenance points should be provided on all equipment. In the design of these accesses consideration must be given to the fact that surfaces are always oily which could lead to such hazards as slipping.
9.2.11 | Where there is a risk of falling, working areas must be properly protected with suitable guardrails.
9.2.12 | Adequate safe working space for operators should be provided. Control systems should be protected from inadvertent operation and be laid out in an ergonomically correct way. Adequate numbers of emergency stops devices should be provided.
9.2.13 | Machines should be fitted with adequate floodlights.
9.2.14 | When installing and removing the jumbo the basic recommendations for traffic movements set out in Section 5 should be observed where applicable and in particular every backward movement should be controlled by a signal man who should also safeguard the workers and the power cables
9.2.15 | Detachable bits should not be replaced whilst drilling is in progress. Changing bits or rods can be dangerous and adequate care should be taken. Correct equipment must always be used.
9.2.16 | Before withdrawing drilling rods the holes must be flushed.
10 | Use of Explosives
10.1 | General
10.1.1 | Only competent shotfirers should be authorised to handle and use explosives. They should be aware of local regulations, if any, and manufacturers recommendations.
10.1.2 | At change of shifts the shotfirer should fully inform his relief of the state of the work at the face.
10.2 | Explosives
10.2.1 | Explosives and detonators not required for immediate use should not be stored in the tunnel.
10.2.2 | Only water resistant explosives should be used in tunnelling.
10.2.4 | The destruction of old or damaged explosives is a hazardous operation and should be done in accordance with accepted safe practice.
10.2.5 | Explosives should in all cases, be used in accordance with local or other appropriate regulations.
10.3 | Detonators
 | Various types of initiation systems are available and selection should be made with local conditions in mind. Detonators should be stored and transported separately from explosives
10.4 | Firing Sets - Firing Lines
10.4.1 | The initiator should match the detonators used.
10.4.2 | Initiators should be adequately maintained.
10.5 | Blasting
10.5.1 | A blasting plan should be drawn up before any blasting is undertaken.
10.5.2 | All blasting should be carried out in accordance with the plan.
10.6 | Transport of explosives
10.6.1 | Detonators and other explosives should be transported separately and should be stored apart until used.
10.6.2 | Only sufficient explosives for immediate use should be transported to the working face.
10.6.3 | Explosives should be transported in containers and/or vehicles specially designed for the purpose. Such containers and/or vehicles should be clearly marked to distinguish them from other vehicles.
10.6.4 | A responsible person should always accompany the explosives during transport.
10.7 | Charging of the Rounds
10.7.1 | Charging should not be undertaken until all drilling in that area has been completed
10.7.2 | In the event of the threat of thunderstorms, charging with electric detonators should be stopped immediately and the working face evacuated. Non-electric detonators should be used in that case.
10.7.3 | Charging and blasting should be done by authorised persons.
10.7.4 | Electric detonators shall only be used where stray currents can be excluded.
10.8 | Precautions before Blasting
10.8.1 | Before proceeding with continuity testing of the firing circuit, care should be taken to remove all persons from the danger zone and guards should be placed to prevent access to the danger zone. Persons in working areas adjacent to the blasting site should be warned of pending blasting operations.
10.8.2 | Guards must remain at their posts until they have received definite instructions to leave.
10.8.3 | Consideration should be given to the use of non-electric systems or electronic (micro-chip) blasting systems
10.9 | Protection against flying rocks
10.9.1 | People should be removed from the blasting area to a safe place where they will be protected from projectiles or flying rock.
10.11 | Precautions after [NAME]
10.11.1 | Adequate ventilation should be provided and atmospheric monitoring carried out to ensure the removal of all hazardous gases before re-entry.
10.11.2 | The shotfirer and assistant should check the face and make safe before allowing work to proceed.
10.11.3 | Before mucking operations the responsible person shall check to ensure that safety precautions have been carried out.
10.11.4 | Vehicles used for the transport of explosives or detonators should be regularly inspected and maintained to check that they do not present any risk to the materials carried.
11 | Planning for Emergencies
11.1 | General
11.1.1 | Every effort should be made to provide a healthy environment for workmen. Personal protection should be regarded as the last line of defence, e.g. respiration and ear protectors.
11.2 | Dust
11.2.1 | The amount of dust generated should be minimised. All dusts are harmful and exposure should be kept within national limits.
11..2.2 | The main consequences from dust exposure are pneumoconiosis and silicosis. The latter can occur after long exposure, where there is considerable quartz content in the airborne dust.
11.2.2 | In its mildest form dust exposure annoys by making sensitive parts of the respiratory tract very uncomfortable. In addition dust reduces visibility and enters the respiratory tract.
11..2.3 | Exposure to some dusts e.g. cement, can cause dermatitis.
11.3 | Protection against dust
11.3.1 | Wet flushing (preferred) or dust extraction should be used during drilling.
11.3.2 | The working face, tunnel walls and muck pile should be watered for at least 15 minutes after every blast and before mucking operations begin. The muck pile should also be watered during mucking operations.
11.3.3 | Dust extraction units or water sprays should be placed at sources of dust emission such as on tunnel boring machines, conveyor transfer points, shotcrete mixing units etc.
11.3.4 | If the above measures are unsuccessful at controlling airborne dust concentrations, additional ventilation should be provided.
11.3.5 | Dust masks for individual protection should only be necessary to use in exceptional cases and for short duration work at that.
11.4 | Gaseous Contamination
 | Toxic gases are generated through the use of explosives, diesel engines, from ground contamination or, more rarely, from natural sources.
 | Sufficient ventilation should be provided to prevent the build up of a toxic or potentially explosive atmosphere in the tunnel.
 | Gases from blasting operations are basically oxides of nitrogen, ammonia and oxides of carbon. Therefore it is necessary to provide powerful ventilation in order to reduce the re-entry time to a minimum. The characteristics of the fume emitted should be considered in the selection of the explosives.
11.5 | Emissions from power units
11.5.1 | Petrol driven internal combustion engines shall not be used underground because of their large emissions of CO (10% of exhaust gas) and the fire and explosion hazard.
11.5.2 | Only low emission or “clean burn” diesel engines or electrically driven or battery operated motors should be used.
11.5.3 | Engines should be properly adjusted and maintained to operate efficiently under prevailing conditions in order to reduce toxic exhaust emissions to the absolute minimum.
11.5.4 | Engines should be effectively silenced so as to achieve a noise level not exceeding LAeg 85 dB(A) as measured in the open, at a distance of 1 m.
11.5.5 | Exhaust systems should be fitted with an efficient catalytic converter and particulate filter.
11.5.6 | Direct injection air cooled engines are preferred for reason of better exhaust emission characteristics.
11.5.7 | Efficient air intake cleaners should be provided.
11.5.8 | Idling of diesel engines should be kept to a minimum.
11.5.9 | Storage of diesel fuel underground should be prohibited.
11.5.10 | All vehicles underground, should have efficient fixed fire extinguishing systems.
11.5.11 | Atmospheric monitoring in the vicinity of any engine should be carried out at least once per month, with the engine running at full load and when idling.
11.5.12 | Exhaust gas analyses should be taken at least once every three months under full load and idling conditions.
11.6 | Ventilation
11.6.1 | Ventilation of the works is always necessary to ensure that the atmosphere is safe for the workers.
11.6.2 | Where diesel engines are used the ventilation capacity shall be rated accordingly.
11.6.3 | For guidelines on adequate ventilation refer to Section 7.
11.7 | Noise reduction measures
11.7.1 | Deafness caused by noise at the working place is a recognised occupational illness, and tunnelling is one of the noisiest occupations. Exposure to a noise level of 85 dB(A) can cause damage to hearing. It has been found that exposure to a high noise level over a period of 40 years can reduce hearing by as much as 40 dB(A). Steps must therefore be taken to reduce the noise.
11.7.2 | As far as possible noise in the environment should be reduced through the use of low noise emission plant and equipment. Where this cannot be done for technical reasons, personal hearing protective equipment must be provided.
11.7.3 | It is recommended that maximum noise levels of equipment be reduced to 85 dB(A)
11.7.4 | These include reduction in noise emission at source of noise generated by machinery through improvement in design of equipment, reduction in exposure and as a last resort, the use of personal protective equipment.
11.7.5 | Personal protection against noise should be used after all other measures have been taken and shown not to have worked.
11.7.6 | Where the noise level is equal to or greater than 80 dB(A), hearing protection should be provided. This is however only a short term solution as the effect of hearing protection is to reduce the noise levels from between 15 and 20 dB(A). As maximum protection is only possible when the protective devices are properly fitted and worn, an effective assessment, fitting and training programme should be put in place.
11.8 | Heat
11.8.1 | Cooling of the tunnel atmosphere should be undertaken when the temperature routinely exceeds 28 C.
11.8.2 | Cooling may consist of increasing the ventilation flow and/or installing cooling equipment.
12 | Electrical Installations
12.1 | General
12.1.1 | All electrical equipment and installations shall be so constructed, installed, maintained, protected and used as to prevent danger. Electrical equipment and its installation should be in compliance with relevant national, CEN, CENELEC and ISO standards, and national regulations.
12.1.2 | Electrical equipment in the tunnel is exposed to mechanical damage and a range of adverse environmental factors including temperature, pressure, humidity, dust, the effects of blasting and potentially explosive gases. It shall be appropriately protected from such exposure. Protection against ingress of dust and moisture shall be to a minimum of IP 54 (see 22.1.8).
12.1.3 | Electrical installations should be inspected and tested by a competent person after commissioning -or, modification and thereafter at regular intervals thereafter and the results of the inspection or test should be recorded.
12.1.4 | Only persons who are competent should be responsible for the operation and maintenance of electrical installations.
12.1.5 | Where there are no national guidelines for assessing competence, the following criteria shall be used:
 | • appropriate level of knowledge of electrical engineering principles;
 | • experience of electrical installation work;
 | • understanding of the installation to be worked on and practical experience of that work;
 | • understanding the hazards which can arise during the work and the precautions to be observed;
 | • ability to recognize at all times whether it is safe to continue working.
12.1.6 | All the relevant technical documentation concerning the installations and the electrical equipment on site should be available on site.
12.1.7 | To prevent accidents caused by people switching on electrical equipment while others are working on it, switches should be locked out with a lock-out device and a padlock. The padlock keys should be under control of the person doing the work.
12.1.8 | Site specific guidelines should be prepared covering the operation and maintenance for electrical equipment and be made available to the appropriate persons working in the tunnel. These persons should also know the steps to take in the event of electric power outage as well as the relevant safety precautions. The guidelines should include:
 | • details of the competent person(s) responsible for electrical equipment;
 | • description of electric equipment and personal safety precautions;
 | • recommended working techniques and the necessary personal skills;
 | • potential  risk identification;
 | • inspection periods;
 | • details of periodic inspections of electric equipment, maintenance strategy and maintenance intervals.
 | • procedures to prevent potential electric energy failures including the provision of back-up supplies,
 | • outline accident plans for dangerous exposures such as fire, absence of air ventilation, failures of dewatering pumps, lighting, etc..
12.1.9 | Steps should be taken to restrict the effect of electrical energy on the surrounding construction work and installations including:
12.1.10 | Protective zones and recommended stand-off distances from existing plant, overhead lines and cables within the high voltage distribution network;
12.1.11 | Prevention of premature detonation of explosives by using non electric detonators when necessary (e.g. with effects of stray earth currents, electrostatic discharges and atmospheric electric energy);
12.1.12 | Standby power should be provided, from an independent mains circuit or by diesel generators, where a power failure could endanger lives e.g. compressed air work, failure of dewatering pumps, failure of ventilation fans or fire-fighting pumps etc.
12.1.13 | Electrical installations should be so planned that safety critical circuits are not broken when other circuits are disconnected or fail.
12.2 | Electricity
12.2.1 | Designs of electric equipment must be compliant with the environment and site where the equipment is operated, especially with respect to electric current accidents and potentially explosive atmosphere.
12.2.2 | All installations should be protected against overload and short-circuit by automatic disconnection from the supply. Continuity of earth protection should be ensured.
12.2.3 | The main causes of electric current accidents are: (were they identified in the risk register?)
 | • accidental contact with live parts;
 | • defective equipment or installations
 | • fault in a protective conductor in the circuit or equipment;
 | • other undesired effects of electric current.
12.2.4 | The circuits for portable equipment, accessories and lighting should comply with Clause 16 of EN 60204-1:1997 with the addition of the following measures to mitigate the problems associated with electrical equipment in a tunnel environment. These should include the use of a residual current protective device with a fault current rating of a maximum of 30 mA or the use of a 110 volt centre earth tap supply. Control circuits should comply with Clause 9 of EN 60204-1:1997, with the addition for handheld pendant controls, that they should operate at control voltages not exceeding 24 volts. Low voltage supplies are those from 50 V AC to 1000 V AC. High voltage supplies are those above 1000 V AC.
12.2.5 | Underground electric equipment should be located in such a manner that it is protected against mechanical damage but remains readily accessible to operating and maintenance personnel.
12.2.6 | A competent electrical engineer shall produce a written scheme for the methods and frequency of inspection and maintenance requirements.
12.2.7 | Regular visual inspection should be undertaken to check that:
 | • electric installations and cabling are not damaged or misused;
 | • functionality of protection against accidental contact are in place (earth leakage circuit breaker, residual current circuit breakers, protective grounding system, enclosure, etc.);
 | • there is sufficient working space around the electric equipment
 | • the underground lighting including emergency lighting works properly.
12.2.8 | Electric equipment which is unintentionally disconnected, should not be repowered until the relevant cause has been identified and any defect repaired.
12.3 | Cables
12.3.1 | Cables for use underground should be selected and installed in accordance with national guidelines. They should be appropriately sized for the expected duty.
12.3.2 | Where cables are buried, markers should be installed to clearly show the position of cables.
12.3.3 | The voltage drop between the point of supply and any electric installation should not be greater than 10% of the nominal voltage. If the cable length makes the voltage drop greater it is necessary to alter the electric power transmission parameters, for example by transformation to a higher voltage.
12.3.4 | High voltage cables are used in tunnelling and such cables must be properly supported and protected against mechanical damage and abrasion. Care should be taken when laying out cables to avoid introducing twists in the cables which could damage the insulation internally. Protection against fire damage should also be considered.
12.3.5 | Cables should be insulated with materials that will not emit toxic gases or smoke when they burn.
12.3.6 | Joints and connections should be suitable for the tunnel environment.
12.4 | Substations and switchgears
12.4.1 | Substations, distribution boards, cables, switches and circuit breakers should be dimensioned to accept the currents and voltages that might foreseeably occur at the particular site during various operational states.
12.4.2 | Only competent persons should enter a substation.
12.4.3 | Electric substations and switchgear should be, equipped by safety plates and inscriptions, and fixed fire extinguishing systems.
12.4.4 | Oil filled circuit breakers, switchgear and transformers should not be used underground to minimise fire load. [NAME] and air switches are to be preferred.
12.4.5 | Switchgear and distribution boards should be protected against damage. Installations and distribution boards should have sufficient clear working space to allow for operation and maintenance. Switchgear and control cabinets on TBMs should not open on to walkways.
12.4.6 | Portable hand-held tools and apparatus should be double-insulated or should be used in conjunction with residual current circuit breakers with the rated residual current not exceeding 30 mA.
12.4.7 | Effective means should be provided for every high voltage circuit to prevent danger arising from earth leakage currents.
12.4.8 | Earth-fault protection can be used in an isolated system. Any fault current should be signalled in case the trip fails to disconnect the power automatically.
12.4.9 | Every circuit or cable should be clearly marked at regular intervals with a unique reference which allows its function and route to be identified from the operating manuals for the installation.
12.5 | Earthing
12.5.1 | The earthing bonding system must meet the earthing wire mechanical strength requirements and accidental contact protection conditions and be accessible to visual inspection with the exception of structure earthing.
12.5.2 | All neutral parts of any electric circuit which require earth protection and all conductive structures in the tunnel (pipelines, rails, etc.) should be adequately earth bonded. Continuity of earthing should be checked periodically.
12.5.3 | It is advisable that earth leakage protection be provided to the following standards:
 | • voltage of or above 1000 V - leakage current not exceeding 5 A or 15% of maximum earth fault current
 | • higher than distribution nominal low voltage
 | - leakage current not exceeding 750 [NAME]
 | • distribution nominal low voltage - leakage current or core balance current not exceeding 300 mA for extensive electricity distribution lines, portable equipment and fixed lighting
 | • residual current not exceeding 30 mA for portable hand tools and apparatuses.
12.6 | Transformers
12.6.1 | Transformer enclosures and switch rooms containing exposed conductors should be locked when the equipment is live unless access for operating purposes is required. The keys should be held by an authorised person.
12.6.2 | Preferably only transformers with air- cooling or non-flammable coolants should be used underground.
12.6.3 | Oil-cooled transformers should only be used in fixed sub-stations above ground remote from working areas.
12.6.4 | Enclosure of the transformer and its location should take into account local operating and environmental conditions.
12.6.5 | Safe means of access and adequate working space should be provided for inspection, maintenance and emergency purposes.
12.6.6 | Suitable fire extinguishers should be provided at all transformer locations. Fire extinguishers should be mounted externally and their locations indicated with relevant safety symbols.
12.6.7 | Appropriate safety signs should be provided adjacent to all electrical installations.
12.6.8 | There should be a means of isolation on the primary side of any transformer unit which should preferably be by an integral isolator and for high voltages should be of the air-break or vacuum contactor
12.6.9 | Any external tap change selector should be securely locked in the selected position.
13 | Used of compressed air as source of power
13.1 | General
13.1.1 | The use of compressed air involves hazards uncommon to any other source of power. Proper maintenance of compressors and air-powered equipment is vital to their continued safe operation.
13.1.2 | Safety demands frequent inspection of all equipment. The frequency of inspections will depend upon the extent and severity of use.
13.1.3 | Compressed air should not be misused to blow down dust from clothes, workbenches or floors. Compressed air entering a body opening can rupture the area creating serious injury or death. A single blast of air can burst an eardrum or permanently destroy an eye. Wearing of hearing protection is recommended.
13.1.4 | uitable attention should be given to noise levels of air-powered equipment. Refer to Section 11.7.
13.1.5 | When using compressed air underground there can be a discharge of oil which means that the air in the tunnel could become polluted.
13.1.6 | To drive machinery by compressed air (pneumatic power) it is essential to have some source of lubrication, if there is no oil in the compressed air supply then it is necessary to introduce an oil bottle into the pipelines.
13.1.7 | The oils necessary for the compressor and the tools it drives should be of a high flash-point. They can cause atmospheric contamination.
13.2 | Air Compressors
13.2.1 | Compressors used underground should be electrically operated.
13.2.2 | Underground compressor stations should be properly protected against falling ground and moving plant.
13.2.3 | The use of low flash point lubricants should be prohibited because of the explosive risk.
13.2.4 | The supply of air should be drawn from the purest and coolest source available.
13.2.6 | Every air compressor having a rating exceeding 0,15 m3 of free air per second should be fitted with temperature control.
13.2.7 | An over-pressure limiting device, capable of passing the entire flow from the compressor should be provided between the compressor and the stop valves on the discharge side.
13.2.8 | A reliable pressure gauge should be provided to indicate the discharge pressure of the compressor.
13.2.9 | Every compressor should be fitted with a nameplate with the following information:
 | •  Manufacturer
 | •  Type
 | •  Year of manufacture
 | •  Volumetric flow
 | •  Maximum working pressure
 | •  Maximum operating speed
 | •  Motor output in kW
13.2.10 | Every compressor should be maintained in accordance with the manufacturer’s instructions.
13.3 | Pressure vessels (Air receivers)
13.3.1 | Pressure vessels should be constructed and inspected in accordance with national statutory requirements.
13.3.2 | Pressure vessels should be kept clean and free from mineral oil or other inflammable material which could ignite under working conditions and material which could cause corrosion or which is liable to chemical reaction resulting in an uncontrolled rise in pressure.
13.3.3 | Pressure vessels should be maintained in a safe working condition at all times.
13.3.4 | Daily maintenance should include draining of any liquid which may have collected in the receiver. For this purpose a suitable drain controlled by a valve should be provided at the lowest part of the receiver.
13.3.5 | In the absence of national statutory requirements, every pressure vessel should be inspected and tested before being commissioned and thereafter inspected at regular intervals of not more than five years.
13.3.6 | Every pressure vessel should have a plate securely fixed to it in a conspicuous place bearing the following particulars:
 | •  Name of manufacturer
 | •  Manufacturing number
 | •  Country of origin
 | •  Year of manufacture
 | •  Maximum safe working pressure and temperature
 | •  Capacity
 | •  Date of last inspection and test
13.3.7 | Pressure vessels should not be modified on site.
13.3.8 | Every pressure vessel should be provided with at least one reliable pressure gauge on which the maximum safe working gauge pressure shall be clearly marked with a red line.
13.3.9 | Every pressure vessel should be provided with at least one over-pressure relief valve capable of passing the maximum inflow of air to the vessel.
13.3.10 | To prevent tampering with such valves, they should be kept locked, sealed or otherwise rendered inaccessible to any unauthorised person.
13.3.11 | Every pressure vessel should be provided with a shut-off valve at the outlet into the mains.
13.4 | Air lines
13.4.1 | Air lines should be manufactured to a recognised national standard and rated for the expected working pressure.
13.4.2 | Only pipes and fittings in good condition should be used.
13.4.3 | Quick coupling metal pipes (including flanged pipes) may be used for the main supply.
13.4.4 | Reinforced polyethylene or rubber hoses may be used for smaller diameters (less than 200 mm) or for low pressures (up to 7 bar).
13.4.5 | Reinforced polyethylene or rubber hoses should be fitted with sturdy couplings.
13.4.6 | Restraints should be fitted across joints in flexible air lines to prevent danger in the event of unexpected disconnection.
13.4.7 | The air line should not be disconnected unless the supply has been cut off and pressure has been reduced to zero.
13.4.8 | Air supply lines should be adequately supported both above ground and in shafts and tunnels. They should be protected from mechanical damage.
13.4.9 | Shut-off valves should be installed in all main supply air lines at regular intervals depending on size of air line but a maximum spacing of 500 m is advisable.
13.4.10 | hut-off valves should be fitted at the entrance to the works and near the end of the supply line to close off air supply in case of damage.
13.4.11 | Discharge valves should be fitted in air lines to reduce air pressure in the air lines when equipment is shut down.
13.4.12 | Air lines and their fittings should be maintained in good condition and leaks should be repaired promptly both to reduce air loss and control noise emission. A drain should be fitted to an air line to enable moisture present in the air line, to be drained off regularly before entering the equipment.
13.4.13 | Filters should be installed in the air line near equipment to prevent solids entering the equipment.
16 | Dealing with water
16.1 | General
16.1.1 | Care should be taken to avoid the works being flooded from outside sources.
16.1.2 | Fissures in rock often contain water under pressure. If water is anticipated, exploratory probing or drilling ahead of the face should be carried out, to confirm the quantity, the quality and the pressure.
16.1.3 | Water containing suspended particles in particular fine sand, and entering a tunnel can over a period of time, create a void behind the tunnel lining.
16.1.4 | The presence of water adversely affects the working environment and can affect the stability of exposed ground.
16.1.5 | The presence of water increases the risk associated with the use of electricity.
16.1.6 | Adequate protective clothing should be provided for those working in wet conditions.
16.2 | Dealing with water
16.2.1 | If water is anticipated, exploratory probing or drilling ahead of the face should be carried out to confirm the quantity, the quality and the pressure. Blowout preventers shall be used during drilling according to the risk assessment.
16.2.2 | If ground water is encountered, and the ground requires sealing, this should be done ahead of the excavated face.
16.2.3 | Measures shall be put in place for the evacuation of workers in case of sudden flooding.
16.2.4 | Water should be removed from the working area either by open drains or by pumps and pipes. Intermediate holding tanks and pumping stations should be set up where water has to be pumped over large distances.
16.2.5 | If open drains are used they should be on the opposite side of the tunnel to the pedestrian walkway.
16.2.6 | Sumps are hazards for persons walking in the tunnel and should be guarded and readily visible to avoid injuries to workers falling into them.
16.2.7 | To avoid flooding, especially in downward sloping tunnels, pumps with adequate reserve capacity should be provided and so arranged that if flooding occurs they will not be put out of action.
16.2.8 | Where the stability of the tunnel face or the tunnel itself is endangered by the presence of water, the tunnelling method shall be chosen accordingly.
16.2.10 | Where water from the tunnel is discharged it may require treatment (settling ponds, etc) to avoid pollution of surface water.
16.2.12 | Where groundwater is lowered during construction adequate standby capacity should be available to prevent interruption of this process.
17 | Underground communication system
17.1 | General
17.1.1 | Good communication throughout the works is necessary for safety and is an aid to efficiency.
17.1.2 | The system adopted should be chosen having regard to the size, length and complexity of the tunnel works; the number and distribution of personnel in the works; the method of construction to be used; the potential hazards in the tunnel; the noise level in the tunnel; the requirements
17.1.3 | An alternative power source should be available for the communication systems.
17.1.4 | Communication equipment should be well maintained and regularly tested.
17.1.5 | Communication cables should be adequately protected from fire and mechanical damage and should not be located adjacent to power lines.
17.1.6 | Equipment should be protected against water and dust ingress to IP 55 where possible.
17.1.7 | Where potentially explosive atmosphere may occur, communications equipment should be explosion protected.
17.1.8 | Direction to the nearest communication set should be clearly signposted. They should be sited as near as possible to the working area, at regular intervals not exceeding 500m along tunnels, in workshops, in the site office, and at the tops and bottoms of shafts. Where compressed air working is being carried out, additional sets will be required to link the locks and plant installation to the site network. There should be a link to the public telephone network for emergency use.
17.1.9 | Communications sets should have acoustic covers or earphones should be used. Large flashing lights are often preferable to a bell as a call sign.
17.1.10 | Emergency lighting should be provided at the communication points.
17.1.11 | Users of communication systems should not be exposed to traffic or other hazards.
17.1.12 | A pre-arranged emergency signal system should be developed (tapping on rails or pipes) for use in emergencies.
17.1.13 | Any signal system adopted, whether sound or visual, shall be clearly displayed adjacent to all telephone sets.
18 | [NAME]
18.1 | General
18.2 | Ground support shall be used unless engineering experience indicates that it is not required. The ground shall be supported wherever loose or fractured material is encountered.
18.3 | The type of support provided shall be appropriate to the nature of the ground exposed, the prevailing groundwater regime and the tunnelling methods used.
18.4 | Support shall be installed as soon as possible after excavation.
18.5 | A competent person shall inspect, and if necessary arrange to have made safe, all working areas before the start of each shift.
18.6 | Supervisors should examine and check support and ground conditions during visits.
18.7 | Methods of support normally used include precast concrete or cast iron segmental lining; rock bolts; shotcrete or sprayed concrete; steel ribs or other structural support (steel, concrete etc or a combination thereof).
18.3 | Rock bolt
18.3.1 | The bolt length and pattern etc should be designed and installed under the close supervision of a competent engineer.
18.3.2 | Persons installing bolts should only do so from under the protection of a previously bolted area or temporary protective canopy. Appropriate access equipment should be provided for this operation.
18.3.3 | Bolts may be mechanically anchored, friction bolts, or resin anchored, partially or fully bonded, tensioned or untensioned. Appropriate tools e.g. torque wrenches etc., should be used to ensure bolts are installed to the required tension.
18.3.4 | Anchorage tests shall be carried out to determine anchorage capacity in the various ground types.
18.3.5 | Where tensioned bolts are used, pre- set tensioning jacks or torque meters shall be available and always used.
18.3.6 | Where mesh or netting is used it shall be installed between the ground and the anchorage plate.
18.3.7 | Spherical washers shall be used between the nut and the anchorage plate when tensioned bolts are installed.
18.3.8 | Mechanically anchored bolts shall be periodically checked to ensure that the plate is secure against the rock.
18.4 | Sprayed concrete / Shotcrete
18.4.1 | Shotcrete application is skilled work and only competent operators should be used.
18.4.2 | The mixture should be designed to meet the specification in terms of workability and strength. It should also be designed to minimise dust emissions.
18.4.3 | Good ventilation and lighting of the shotcreter’s work place are essential during shotcreting.
18.4.4 | Shotcrete support is dependant on adequate bond with the rock. Surfaces contaminated with oil, dust or mud shall be safely cleaned before applying shotcrete. Shotcrete will not bond to excessively wet rock surfaces and in these cases remedial measures are necessary.
18.4.5 | The quality of the shotcrete shall be verified by routine inspection and testing.
18.4.6 | During shotcreting, no other operations should be carried out in the vicinity.
18.4.7 | The wet mix shotcrete process should normally be used. It produces less dust and is less susceptible to rebound than the dry process.
18.4.8 | Accelerators should be used in correct proportions as per ’manufacturers instructions. Non-caustic accelerators are to be preferred.
18.4.9 | Protective clothing and respirators should be used only when no further reduction in dust emissions can be made through altering the mix.
18.5 | OTHER STRUCTURAL SUPPORT (Steel ribs, steel sets etc)
18.5.1 | Damaged, deformed or corroded support materials should not be used.
18.5.2 | The support system should be installed in contact with the ground.
18.5.3 | Any voids between the structural support system and the ground should be filled with grout, concrete or shotcrete.
18.5.4 | Structural supports are to be adequately braced to one another with connecting bolts or girders. Supports shall be fully and rigidly assembled with all bolts and plates in place.
18.5.5 | Lagging, preferably of steel, and appropriate to the spacing of the support sets, should be fastened to the extrados of the sets over the area of ground where support is required.
18.5.6 | Support ribs should not be supported on loose material.
18.5.7 | Support systems should be inspected regularly to determine the condition of the arches and bases; the condition of the connecting pieces and braces and condition of the lagging
18.5.8 | All necessary remedial work identified by the inspection shall be carried out expeditiously.
19 | Monitoring of the tunnel atmosphere
19.1 | General
19.1.1 | In the absence of national statutory limits on exposure to harmful substances, the national limits from an adjacent country should be adopted.
19.1.2 | Monitoring for oxygen concentration should be carried out routinely by the use of electronic atmospheric monitoring equipment. Where the presence of gaseous contaminants is foreseeable, continuous monitoring by electronic equipment should likewise be carried out.
19.1.3 | Further guidance on the basic principles for a clean and healthy tunnel atmosphere is set out in Section 11.6 of this document.
19.1.4 | A range of gases including methane, hydrogen sulfide and radon dissolved in ground water may enter the tunnel.
19.1.5 | Ventilation should be used to dilute contaminants and to prevent the build up of an irrespirable atmosphere.
20 | Fire
20.1 | General
20.1.1 | As part of the tunnel planning process a risk assessment shall be undertaken of the potential for fire underground. Sources of flammable materials and potential sources of ignition should be identified. A plan to minimise risk should be drawn up.
20.1.2 | At the planning stage a decision should be taken whether to establish and train a special on-site rescue team to carry out rescue operations in emergency situations. [NAME] with the public emergency services is essential for disaster planning.
20.1.3 | Adequate evacuation of workmen shall be possible. [NAME] and rescue ways underground should be kept free of smoke by ventilation and/or other technical installations such as smoke barriers.
20.1.4 | Strict safety rules and work permissions should be applied for all work with open flames
20.1.5 | There should be one or more water spray curtains across the tunnel capable of being activated in an emergency to act as a barrier to the movement of smoke.
20.1.6 | Low flammability hydraulic oils and greases should be used.
20.1.7 | All flammable and combustible waste materials, grease, lubricants or flammable liquids shall not be allowed to accumulate where they can create a fire hazard.
20.1.8 | Fire fighting equipment provided on the works shall be strategically located, readily accessible, plainly marked, properly maintained, and inspected periodically. All mechanical plant major items of electrical equipment should be fitted with fixed fire extinguishing equipment. Records shall be kept of such inspections.
20.1.9 | Additional fire extinguishing equipment should be provided in accordance with the risk assessment..
20.1.10 | Fire alarm systems adequate to warn all employees shall be provided and maintained in operating condition.
20.1.11 | Gasoline or liquefied petroleum gases shall not be permitted underground.
20.1.12 | An evacuation and fire fighting training programme for all underground workers should be undertaken in order to prepare for possible cave-ins, flood, gas, explosion, fire or other disasters.
20.1.13 | [NAME] self rescuers should be carried by everyone underground.
20.1.14 | Evacuation drills shall be held for each shift at least once every 6 months. This period could be shortened if shown to be necessary by the risk assessment. These evacuation drills shall involve all employees on each shift and shall include activation of the fire-alarm system followed by evacuation of all men from their work areas to the surface or to designated central evacuation points at some time other than a shift change.
20.1.15 | All employees involved in the escape and evacuation plan for an underground operation shall be instructed at least once each calendar year on current escape and evacuation plans, use of self rescuers, fire alarms, and applicable procedures to be allowed in case of fire or other emergency.
20.1.16 | When welding or cutting with an arc or open flame, or thawing pipes electrically (excluding heat tape) or soldering with an open flame, a adequate fire extinguisher shall be provided.
20.1.17 | Fan housings and air ducts connecting main fans to underground openings shall be fire-resistant.
20.1.18 | Electronic atmospheric monitoring equipment shall be used to test for oxygen deficiency.
20.1.19 | The carrying of matches or other flame-producing materials shall be prohibited in all underground operations where fire or explosion hazards exist.
22 | Content of the HSP in regards to these hazards
22.17 | Occupational Health
22.17.1 | The HSP should set out details of the occupational health arrangements The contractor should have a system to ensure that all employees have access to appropriate occupational health provision and health surveillance if this has been recognised as a requirement through risk assessment.
22.17.2 | The occupational health system should describe how the contractor intends to monitor these procedures to ensure risk assessments, control measures and health surveillance programmes are effective and maintained. It should clearly define and allocate responsibilities.
22.17.3 | Specific consideration should be given to establishing clear methods of communication to provide all employees with information on the occupational health provision and the policies for its effective implementation
22.17.4 | Where health surveillance has been recognised as a measure required from the risk assessment process this should be provided and recorded.