Star.pngStar.pngStar grey.pngStar grey.pngStar grey.png

Tunnel

From Roader's Digest: The SABRE Wiki
Jump to navigation Jump to search
Tunnel
Dublin Port Tunnel, Entrance and Exit, Whitehall, Dublin, Ireland.jpg
The Dublin Port Tunnel in Ireland.
Cameraicon.png Pictures related to Tunnel
View gallery (32)


A tunnel is a structure carrying a route underground for a distance. A large majority of road tunnels are built under rivers and through hills, though some may be built to allow development above the road. In the UK, some tunnels are referred to as underpasses - there are no distinct rules as to naming conventions.


Types of Tunnel

Cut and Cover

The Cut and Cover tunnel is unusual, as it usually involves digging out an open trench in which the road is placed, and then is given a 'lid' afterwards to create the tunnel. These tunnels are often employed in urban contexts where a road is deemed obtrusive if left uncovered. The glaring exception to this design rule is the Weston Hills Tunnel which when built featured two distinct tubes which were then covered with earth when the hill above was reinstated.


Bored

The Bored tunnel is created by a Tunnel Boring Machine (TBM) and can be very costly, but it is the only feasible way to tunnel through solid rock and in most cases underneath riverbeds. In some instances bored tunnels are constructed underneath urban areas, for example the Brynglas Tunnels on the M4. The oldest road tunnel still in active use in the United Kingdom, the northbound Blackwall Tunnel on the A102 is of the bored type.


Immersed Tube Tunnels

Immersed Tube

The Immersed Tube tunnel is a relatively recent method of tunnelling and as a result is still extremely costly but can be placed with relative ease underneath river estuaries. The tunnel is usually fabricated off site and then 'lowered' into a trench dredged in the water. The sections are linked together and pumped dry before the roadway is constructed and the tunnel fitted out.

See also

Category:Tunnels





Tunnel
Related Pictures
View gallery (32)
Horn Hill Tunnel - Geograph - 1228863.jpgN71 summit tunnel - Coppermine - 12863.jpgLimehouse Link western portal.jpgIMG 5847.JPGSh20-tunnel.jpg
Road Basics
Physical layoutSingle track • Single carriageway • Dual carriageway • High Quality Dual Carriageway • Road Widths • Urban Streets • Abandoned Road
Legal typesAll-purpose Road • Special Road • Motorway • Trunk road • Principal road • Classified Numbered road • Classified Unnumbered Road • Unclassified road • Primary Route • Non Primary Route • Right of Way • Unadopted road
Road numbers1922 Road Lists • Classification • Defunct road • Euroroutes • MoT Maps • National Cycle Network • Numbering principles • Numbering anomalies • Disputed Numbers • Recycled number • Unallocated numbers • Fictional Road Numbers • Junction numbers • Essential Traffic Routes
Road FeaturesArterial Road • Automatic Bollard • Balancing Pond • Belisha Beacon • Bott's Dots • Bypass • Cannon • Cats' Eyes • Cattle Grid • CD Lanes • Central Reservation • Chopsticks • Crash Barrier • Cuttings and Embankments • Cycle Lane • Emergency Phone • Escape lane • Expressway • Fingerpost • Flare • Ford • Gore • Green Bridge • Green Wave • Hairpin bend • Hard shoulder • Island • Junction • Layby • Level Crossing • Local Access Road • Managed Motorways • Milestone • Multi Lane Drop • Multiplex • No-Car Lane • Nose • Oxbow Road • Parapet • Petrol station • Play Street • Raised Pavement Markers • Ramp Metering • Retaining Wall • Road Studs • Roadside Art • Roadside Quarry • Roadworks • Secret motorway • Signage • Smart Motorway • Snow pole • Speed Limit • Spur • Street Lighting • Surface Dressing • Temporary terminus • Throughpass • Tidal Flow • Tiger tail • Toll booth • Traffic cone • Traffic Signals • Tunnel • Vehicle Recovery • Walking and Cycling Friendly Road • Weaving • Wig-Wag Signals • Winter Maintenance • Zip merge
Traffic CalmingBuild-Outs • Chicane • Dragon's Teeth • Home Zone • Low Traffic Neighbourhood • Pinch Point • Quiet Lane • Rumble strips • Safety Cameras • Sleeping Policeman • Speed bump
Public Transport FeaturesBus Lane • Bus stop • Guided Busway • Park and Ride • Tramway • Trolleybus System
Other termsAnderson report • Guildford Rules • Highway Authority • Highway Code • Model Traffic Area • Motorway alphabet • Pre-Worboys • Primary Destinations • Roads by 10 • Transport alphabet • Worboys report
AcronymsAADT • ADS • ANPR • ATM • DfT • GSJ • HA • HATO • HE • HETO • HQDC • LAR • LILO • LTN • MOVA • NCN • NMU • NRA • PBU • POPE • PTS • PFI • RCS • SABRE • SCOOT • SSD • SON • SOX • SRN • TEN-T • TERN • TfL • TII • TOTSO • TRO • TSM • TSRGD • UTC • VAS • VMS • VSL


SABRE - The Society for All British and Irish Road Enthusiasts
Discuss - Digest - Discover - Help