Bat bridge
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
Bat structures in the UK designed and constructed between 2004 and 2009
| Scheme Name | Road Number | Road Opened | Approx Length of Structure (meters) | Single or Dual Carriageway | Cutting/Embankment/At Grade | Approx Construction Cost of Structure |
|---|---|---|---|---|---|---|
| Dobwalls (2 Structures) | A38 | June 2008 | Structure 1—59.47m Structure 2—70m | Dual | At Grade/In Cutting | £300,000.00 |
| Haydon Bridge | A69 | April 2009 | 19.5m between support posts | Single | In cutting | £60,000.00 |
| High and Low Newton | A590 | April 2008 | 33m span between timber supporting posts | Dual | In cutting | £45,000.00 |
| Parton to Lillyhall | A595 | Dec 2008 | 34m span between supporting steel structures | Dual | On embankment | £34,133.00 |
A497 Pwllheli
In 2006, followihirng 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
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
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
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]
References
- ↑ New bypass going 'batty' to help the environment. Western Morning News, The Plymouth (UK). April 5, 2008. Retrieved 2009-09-12
- ↑ 2.0 2.1 "House of Lords Written Answers 10 November 2009: Bats". United Kingdom Parliament. Retrieved 5 June 2011.
- ↑ "UK | Wales | North West Wales | 'Green' road helps bats to cross". BBC News. 2006-05-02. Retrieved 2009-09-12.
- ↑ 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.
- ↑ "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.
- ↑ "Road closure for new aerial bat crossing". BBC News. 30 January 2010. Retrieved 5 June 2011.