COPYRIGHT © AREMA 2008 of 421 TUNNELS. COPYRIGHT © AREMA 2008 of 422 General Tunnel Inspections present unique challenges Track Time Sensitive Good lighting.

COPYRIGHT © AREMA 2008

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TUNNELS


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General

• Tunnel Inspections present unique challenges• Track Time Sensitive• Good lighting source required• Various types of Tunnels and

– Construction Materials• Conditions found may warrant Expert Evaluation

of structure


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SAFETY

• Confined / Enclosed Space• Fumes from motorized Inspection Vehicle• Adequate Lighting• Walking Hazards- Wet / Ice• Wildlife


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External Environment

Note areas over & around Portals• Vegetation• Ground Water• Adjacent Slopes• Rock Slopes


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Internal Environment

• Natural Gas Pockets / Ground Water

• Conduits for Utilities / Fiber Optics

• Cut-Outs for Inspectors

• Drainage

• Pumps


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Vegetation Adjacent Slopes


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Rock Slopes


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Portals (Tunnel Inspection)

• Openings at each end of Tunnel

• Headwalls / Wingwalls

• Concrete/Stone/Timber/Natural Rock– Height of Headwall / Wingwalls– Stability / Structural Integrity

• Lateral movement / water seepage

– Note Condition / Deficiency• Timber Decay / Concrete Cracks,Deterioration


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Headwalls(date)/Wingwalls


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Natural Rock Portal


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Drains in Wall


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Tunnel Shaft

• Fundamental Tunnel Structure– Detailed Inspection Notes Thru Tunnel– Permanent Stationing Makers Thru Tunnel

• Various Types of Construction or Combination of Types of Construction

- Natural Rock


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Natural Rock


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Natural Rock-Anchor Bolts


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Timber & Steel Sets

• Timber Posts on Sides of Tunnel with Timber cut at angles to form Arch

• Timber Mud Sills on Stone or Concrete

• Spacing of Timber Sets determined by stability of the surrounding material

• Steel Sets are fabricated similar to the Timber Sets construction with Steel Beams


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Original Construction


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Timber Portal /Shed


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Steel Set / Lagging


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Steel Set / Lagging


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Lagging / Cribbing

• Lagging-Timber or Steel placed horizontally between Timber or Steel Sets

• Lagging can fully line the tunnel or support only unstable areas

• Cribbing/Packing: Material Placed behind Lagging or Liner to fill void between lagging and failed material.


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Cribbing Behind Liner


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Concrete / Masonry

• Reinforced Concrete Walls / Arch

• Masonry Walls / Arch ( Brick, Stone)


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Concrete Lined Tunnel


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Brick Lined Tunnel


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Steel Lining

• Corrugated Steel

• Ribbed Tunnel Liner Plates


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Tunnel Floor

• Natural Ground when Tunnel was cut

• Struts below ballast to each side of Tunnel

• Reinforced Concrete


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Problems / Conditions

• Natural / Exposed Material– Cracks, Openings, Movement– New pieces of Rock on floor– Loose Rock Bolts, Anchors


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Material on Tunnel Floor


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Loose Rock Bolts


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• Timber Sets / Lining– Decay; Sound and/or Drill for voids– Bottom Sill; Bearing Area, Crushing, Bulging– Joints, Gaps, Alignment– Bolts, Drift Pins


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• Steel Sets / Lining– Benchwall: Anchors, Corrosion– Columns / Struts: Corrosion, Section Loss,

Buckling / Alignment– Bulging in Walls / Arch


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Failed Steel Liner


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• Lagging: Timber, Steel– Decay , Corrosion, Section loss– Openings at Seams / Joints, Bulging– Ground or Failures behind lagging


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• Concrete / Masonry Lining– New Cracks, Spalling, Bulging– Movement at Construction Joints– Water Seeping, weep holes– Brick / Concrete on floor– Movement , Hinging at Spring Line– Bulging of Walls and Arch – Benchwall / Footer


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Failed Concrete Liner


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• Tunnel Floor / Roadbed– Track Surface– Muddy / Pumping / Fouled Ballast– Drainage Ditches / Culverts

• Train Impacts / Clearance– Signs of Impacts– Verify Dimensions-

• Top/Rail & Centerline Track


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Impact Damage


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Tunnel Inspection Checklist

• PORTALS– Soil / Rock Stability– Condition of Headwall and Wingwalls– Drainage behind Headwall and Wingwalls– Surface Drainage


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• SHAFT– Clearances-Bulges in Ceilings / Walls– Fractured or Scaling Stone– Condition of Rock Bolts and Anchors– Condition of Timber/ Steel Sets /Lagging


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• SHAFT– Condition of Concrete / Masonry Lining

• Bulges• Cracks• Tuckpointing• Surface voids


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• SHAFT– Tunnel Floor

• Debris on floor indicating problems• Buckling or heave• Fouled Ballast• Drainage• Water / Ice accumulation


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EMERGENCYIf the bridge inspector encounters a tunnel condition that affects the safe operations of trains in, or near the tunnel, contact the railroad dispatcher and responsible authority to stop any trains and arrange for immediate repairs. Criteria for limits of acceptable/tolerable conditions must be provided by the Railroad Owner or their designated engineer based on the principles of acceptable rating contained in the appropriate chapter of the AREMA Manual for Railway Engineering

COPYRIGHT © AREMA 2008 of 421 TUNNELS. COPYRIGHT © AREMA 2008 of 422 General Tunnel Inspections present unique challenges Track Time Sensitive Good lighting.

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