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
Stainburn and Great Clifton Bypass A66 December 2002 Gantery 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
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

[2]

A497 Pwllheli[edit]

In 2006, following the upgrade of the A497 between Pwllheli and Criccieth, a bat bridge was installed to help the six species of bats in the area to cross the road.[3]

A465, Gilwern to Abergavenny[edit]

On the recent upgrade of the A465 in 2007 near Abergavenny in Wales, two bat bridges were constructed in the locations where full bridges previously stood to aid the navigation of bats.[4]

A38, Dobwalls[edit]

The A38 Dobwalls bypass, a section of dual carriageway bypassing the village of Dobwalls was completed in 2008. The bat bridges here are much more elaborate and sophisticated than the earlier Welsh structures, which consist of cables strung from poles. At a cost of £250,000,[5] 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.[2]

A487, Groeslon[edit]

A bat bridge was installed in January 2010 on the A487 bypass in Groeslon near Caernarfon, Wales. The road runs through the Glynllifon Special Area of Conservation which is home to a lesser horseshoe bat colony.[6]

Biberach an der Riss, Baden-Wuerttemberg[edit]

Two metal bridges were built at Biberach an der Riss, Baden-Wuerttemberg, Germany in 2013 at a cost of £375,000.[7]

Criticism[edit]

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. [8][9]

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. ^ a b "House of Lords Written Answers 10 November 2009: Bats". United Kingdom Parliament. Retrieved 5 June 2011. 
  3. ^ "UK | Wales | North West Wales | 'Green' road helps bats to cross". BBC News. 2006-05-02. Retrieved 2009-09-12. 
  4. ^ 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. 
  5. ^ "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. 
  6. ^ "Road closure for new aerial bat crossing". BBC News. 30 January 2010. Retrieved 5 June 2011. 
  7. ^ 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 Read more: http://www.dailymail.co.uk/news/article-2486691/German-council-spending-375-000-bridges-new-bypass-used-BATS". Daily Mail. Retrieved 15 June 2014. 
  8. ^ 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. 
  9. ^ "Bat bridges don’t work". University of Leeds. 14 June 2012. Retrieved 15 June 2014. 

See also[edit]

External links[edit]