Bat bridge

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Bat Bridge on the A38 Dobwalls Bypass, Cornwall, UK. (2009)

A bat bridge is a structure of varying construction crossing a new or altered road to aid the navigation of bats following the destruction of a hedgerow, and to cause the bats to cross the roadway at a sufficient height to avoid traffic. Bats are thought to follow the lines of hedgerows and woods, and removing these may confuse the bats.

The theory is that these "bridges" will be seen by the bats' sonar as linear features sufficiently similar to the old hedgerows as to provide an adequate substitute.[1] The Highways Agency is performing a study of those on the Dobwalls bypass to determine if this assumption is justified.

Usage[edit]

Bat structures in the UK[edit]

Scheme Name Road Number Road Opened Approx Length of Structure (meters) Single or Dual Carriageway Cutting/Embankment/At Grade Approx Construction Cost of Structure Other details
Stainburn and Great Clifton Bypass A66 December 2002 Gantry Single (three-lane carriageway)
High and Low Newton A590 April 2008 33m span between timber supporting posts Dual In cutting £45,000
Dobwalls
(2 Structures)
A38 June 2008 Structure 1—59.47m
Structure 2—70m
Dual At Grade/In Cutting £300,000 These bridges are more elaborate and sophisticated than the earlier Welsh structures, which consist of cables strung from poles. At a cost of £250,000,[2] two bat bridges were constructed. One of these, pictured, consists of three steel towers with cables suspended between them carrying mesh panels. The other consists of a single span of cables and mesh panels between concrete and steel anchors either side of a cutting. A third bat-crossing consisted of a raised parapet modification to a new road bridge.[3]
Parton to Lillyhall A595 Dec 2008 34m span between supporting steel structures Dual On embankment £34,133
Haydon Bridge A69 April 2009 19.5m between support posts Single In cutting £60,000
Pwllheli and Criccieth A497 2006 Single At Grade A bat bridge was installed following the upgrade of the A497 to help the six species of bats in the area to cross the road.[4]
Elveden [A11]] 2014 Dual Various Five bat bridges.[5]
Gilwern to Abergavenny A465 2007 Dual Embankment Two bat bridges were constructed during road upgrade in locations where full bridges previously stood.[6]
Groselon A457 2010 Single The road runs through the Glynllifon Special Area of Conservation which is home to a lesser horseshoe bat colony.[7]

France[edit]

The first bridge to be installed in France is on the A65 motorway between junctions for Roquefort and Caloy in the Landes department.[8]

Two additional bat bridges were completed in November 2012 near Balbigny, on the A89 motorway.[9][10]

Germany[edit]

Two metal bridges were built in 2013 to protect the Mouse-eared Bat at Biberach an der Riss, Baden-Wuerttemberg. The structures cost £375,000.[11][12]

Criticism[edit]

Overall cost of bat bridges has been criticised in the House of Lords by Lord Marlesford.[13]

A team from the University of Leeds examined the effectiveness of bat bridges, gantries and underpasses. They found one underpass, placed of a commuting route, was used by 96% of bats but few bats used the other underpasses and gantries preferring routes which put them in the path of traffic. [14][15]

See also[edit]

References[edit]

  1. ^ "New bypass going 'batty' to help the environment". Western Morning News, The Plymouth (UK). April 5, 2008. Retrieved 2009-09-12. 
  2. ^ "New Bat bridge for bypass : Marishal Thompson Group - Tree Subsidence, Arboriculture, Ecology and Landscape Architecture throughout the UK". Marishalthompson.co.uk. Retrieved 2009-09-12. 
  3. ^ "House of Lords Written Answers 10 November 2009: Bats". United Kingdom Parliament. Retrieved 5 June 2011. 
  4. ^ "UK | Wales | North West Wales | 'Green' road helps bats to cross". BBC News. 2006-05-02. Retrieved 2009-09-12. 
  5. ^ "A11 Elveden bypass to be shut for bat bridges". BBC News. 2014-08-04. Retrieved 2015-04-02. 
  6. ^ Roberts, Geneviève (2007-03-31). "How did the bats cross the road? By using the special 'bat bridge' - Nature, Environment". London: The Independent. Retrieved 2009-09-12. 
  7. ^ "Road closure for new aerial bat crossing". BBC News. 30 January 2010. Retrieved 5 June 2011. 
  8. ^ Un couloir à chauves-souris, Sud-Ouest, février 2012
  9. ^ Reportage de France 3
  10. ^ Photographies de l'installation des ouvrages
  11. ^ O'Keeffe, Hayley (3 November 2013). "German council under fire for spending £375,000 on two bridges over new bypass which can only be used by BATS". Daily Mail. Retrieved 15 June 2014. 
  12. ^ "Warum fliegen die nicht einfach drüber?". Koelner Stadt-Anzeiger. 2013-11-02. Retrieved 2 April 2015. 
  13. ^ "Bridges too far? The £500,000 bat crossings". 
  14. ^ Berthinussen, Anna; Altringham, John; Fenton, Brock (13 June 2012). "Do Bat Gantries and Underpasses Help Bats Cross Roads Safely?". PLoS ONE 7 (6): e38775. doi:10.1371/journal.pone.0038775. 
  15. ^ "Bat bridges don’t work". University of Leeds. 14 June 2012. Retrieved 15 June 2014. 

External links[edit]