• Built by Telford • Opened in 1826 • Joins the mainland to Anglesey over the Menai Strait • A5 – Holyhead to London • Grade 1 listed • 1845 - Railway Act between Holyhead and Chester was passed • Built by Stephenson • 1846 – Foundations are laid • 1850 – Bridge opens to train traffic • Grade 2 listed 23RD May, 1970 • Designed by Husband & Co • The new lattice steel arches built on the original tower jacking points • 1972 – Bridge re-opens to rail traffic • 1977 – Construction of the road deck starts • 1980 – Bridge opens to vehicles SOME GENERAL CONCLUSIONS
• a)There has been some outstanding engineering in crossing the straits • b)The importance of the route in terms of connecting the UK to Eire and beyond • c)The increased levels of traffic and unsuitability of the Menai suspension bridge for traffic • d)That they possibly wouldn’t of considered wind baffles in 1980 • So, what’s happened between 1980 and now?
OTHER ISSUES • No UPS – Cameras/Signs/Monitoring • Location of Anemometers • TTM Arrangements – not Ch.8 • Engineers can’t respond • Used several publically available forecasts to make judgements OTHER ISSUES
• Differing wind models • Interesting when systems failed
WHY IS THAT IMPORTANT?
• Emergency services – • Police – Resource to manage bridges • Ambulance – NO HOSPITAL • Fire – Wylfa etc. • Industry • Holyhead Port – Freight • Tourism • Utilities • Public - Commuters • Schools • Council IMPROVEMENTS • New report (Atkins)
Threshold at Threshold Operational Actions Anemometer Stage 1 40mph Bridge open with: • 30mph speed limit • Caravans to use Menai Suspension Bridge Stage 2 55mph As Stage 1 plus: • High sided vehicle ban Vehicle Speed Vehicle • Consider single way ‘batching’ 10mph 30mph 50mph Stage 3 70mph Total closure of the bridge to all vehicles Car >100 >100 >100 Van 98 97 92 Long wheel base, High Roof Van 83 81 76 3.5t Luton Box van 93 91 88 7.5t Box van 81 79 75 18t Rigid Box van 92 90 86 44t Rigid and Drawbar trailer 84 82 78 44t Articulated HGV 83 81 77 Coach 98 96 92 Double Decker Bus 85 83 79 Small, lightweight Caravan 64 61 55 Large Caravan 69 66 60
Threshold Vehicle threshold Anemometer value Threshold at Anemometer
Stage 1 50mph 42mph 40mph
Stage 2 70mph 58mph 55mph
Stage 3 - Standard 85mph 70.8mph 70mph
Stage 3 - Dynamic NA NA 100mph IMPROVEMENTS • New report (Atkins) • Upgraded signing system
Sign A1 Sign A2 Sign B1
Sign B2 Sign C Sign D
Sign E Sign F Sign G
Sign H Sign I1 Sign I2
IMPROVEMENTS • New report (Atkins) • Upgraded signing system • UPS backed systems • NWP Response Plan
IMPROVEMENTS • New report (Atkins) • Upgraded signing system • UPS backed systems • NWP Response Plan • New Control Room System
IMPROVEMENTS
• New MetDesk Forecasts
IMPROVEMENTS
• New MetDesk Forecasts • New Procedure
CHALLENGES • TTM if wind speeds went over 55mph until the new system was installed • Limitations of existing kit – 3 aspects • New signing system remains advisory • NWP won’t attend a ‘planned’ event. • TTM only installed w/speeds <36mph
FORWARD THINKING