niddry burn bridge improvements

client - network rail

• Bridge at Winchburgh on the Edinburgh to Glasgow Railway Line (EGM1).
• The bridge was subject to flooding on a regular basis and had a flood warning system in place forcing the line to close once every 2 years. This was unacceptable and had to be reduced to once every 20 years. 
• A flood study was carried out which highlighted that downstream of the bridge there was dense vegetation growing in the river bed that caused restriction to the water flow. The bridge also caused a 'bottle neck' effect on the flow of water in flood conditions, causing further flow restrictions and causing a flood on the upstream side.
• The only viable option was to install a hydraulic deflector plate to improve the flow of water below the bridge. The deflector plate was designed as a steel plate with a curve at the bottom which causes water to flow at a higher speed under the bridge, causing flood levels to reduce on the upstream side. 
• The deflector plate was attached to the abutments and central pier rather than the bridge superstructure to prevent additional loading to the bridge deck.