Statistics showing increased traffic volumes were beginning to paint a bad enough picture, he contends, even before a recent investigation revealed the breaking of corroded internal wires within the main cables. 'Now we have to seriously consider taking trucks off the bridge, banning all commercial vehicles over 3.5 tonnes by 2013 if this deterioration continues uninterrupted and within this scenario, unless a second road bridge begins construction soon, we will be left without a crossing for some considerable timespan."

When the bridge opened in 1964 it was at full strength with a safety factor of 2.6 and well capable of accommodating four million vehicles annually, including trucks at the then maximum GVW of 22 tons.

With enlarged traffic volumes and substantially increased lorry gross weights, but not much more per axle, the safety factor has dropped to 2.3.

"We must never go below the figure 2,' stresses Alastair Andrew. 'This figure is not arbitrary, it is calculated on bridge traffic load to half its ultimate strength. If current trends continue we will be at '2' in 2013. Then we act!"

"Combined with cable corrosion, this is serious news and could soon have an effect on heavy goods vehicles which make up half of our live bridge loading, but only account for 5% of the traffic flow."

"Admittedly, truck drivers do tend to stay away from peak crossing times in the morning (7-8am) and evening (4-5pm), but inadvertently during the 'quieter' times they then create a bigger footprint on the bridge."

"In any given day however, the bridge is now carrying twice its design load of traffic, averaging 24 million in 2005, a far cry from the four million in its first full year. Interestingly, a 1962 projection, made before the bridge was even built, foresaw a need for a second bridge when annual traffic levels reached 11 million. That's the way it worked on the Severn and now they have two bridges carrying annually between them only one million more vehicles than the Forth Road Bridge."

"I suppose some help may come from the new three lane single carriageway Kincardine Bridge when it opens in 2008, but then the existing bridge is to close for extensive maintenance and, in addition, when we close the FRB to high sided vehicles, we gridlock Kincardine anyway."

Alastair Andrew is conscious of the problem that sudden diversions cause road haulage operators and is working to supply accurate weather forecasts two days in advance, even relayed to drivers by GMS to tell them the bridge is closed due to high winds and when it is likely to open.

It is appreciated that north/south bound commercial vehicles have little option but to use the bridge, but the bridgemaster would prefer to see a 44 tonner paying £5 rather than £2 to cross. 'We could then allow buses free passage and maybe take some commuter cars off the bridge which incidentally, is suffering greater tarmac damage from the use of super single tyres on heavy commercial vehicles."

"We should also be able to speed up CV crossings at off peak times with electronic tolling linked to a tag on the truck's windscreen. A number of local hauliers have volunteered for trials whereby tagged trucks will drive straight through dedicated toll lanes. But unfortunately we will require all booths in payment operation and all 100 staff on the job during peak times, when the maximum possible 3,600 vehicles an hour cross the bridge."

Core Business

"However the big, unanswerable problem that is causing the Scottish Executive to hover over deciding on the second crossing, is the true state of corrosion in the main cables and can this be arrested?

The 2ft diameter cables both comprise 11,600 individual wires cocooned by a wrapping wire and collectively they can take 14,000 tonnes of tension, but 85% of that comprises the dead weight of the bridge itself.

The recent tests on the cables were instigated under a recent United States Code of Practice for cable investigation and although only 4% of one main cable was tested, when the circumference bindings were loosened broken wires were seen to drop out due to corrosion causing the metal to break.

Recalls Alastair Andrew, 'the Americans were shocked, because the bridge is so young and they, as part of this £2.4 million survey, were able to analyse the depth of corrosion from 'bits' starting on the wire going towards a brittle structure and subsequent snap."

"And in this context this opens up a further style of investigation, using acoustic monitoring to listen for more breaks. The results of this exercise will be sent to Canada for analysis and although in many ways it is a health check, we all hope we have seen the worst of the corrosion."

So with the Americans having identified the problem and the Canadians monitoring it, it's time for the Japanese to come onboard with 'cable dehumidification' where the cable is wrapped in a neoprene sheaf, thereafter dried air is injected and the air coming out the other end is measured for moisture, but this is a long term process, since it will take at least until 2008 for the cables to dry out and 2012 for the final result that will indicate whether this treatment has been a success.

"Obviously we are aware of the important role the Forth Road Bridge plays in the economy of the east of Scotland, so we are leaving no stone unturned to keep the bridge open. We have even considered changing the main cables but it would be impossible to replace them without closing one whole carriageway. Consultants are on the case and although it would be expensive, it would certainly be cheaper than a new bridge,' suggests Alastair Andrew.

"At FETA we are all desperate for options, but returning to cross-firth ferries is not one of them! And if the new bridge is to be built, the opportunity would be in place to design-in future ideas such as tram lines as well as roadways, offering direct public transport for instance from Dunfermline to Edinburgh Airport. Wind shielding could also be built-in to help high sided vehicles and of course the new bridge would be linked to the M9 and share an existing roundabout in Fife."

Forth Estuary Transport Authority are also heavily involved in upgrading the roads infrastructure on the south side of the bridge where the A8000 has been a constant concern due to continuous congestion on the only non-dualed piece of road between London and Aberdeen.

However, £39 million has been earmarked to create a parallel road built to motorway standards. The Scottish Executive has granted £24 million with FETA providing £15 million out of toll generated income.

Good News: Bad News

THE FETA proposals to raise Forth Road Bridge tolls for HGVs from £2 to £10 have been quashed by the Scottish Executive. However, if the 'safety factor' on the bridge further decreases, to a factor of 2, then no HGVs (above 3.5 tonnes GVW) will be allowed to cross. This could happen by 2013.

Severn Bridge Worse!

Worsening corrosion on the original 40 year old Severn Bridge has led to the enforcement of weight restrictions.

In a more advanced stage than the Forth Road Bridge, corroded wires in the structure's suspension cables have reduced its load carrying capacity.

Heavy goods vehicles will only be able to travel in one lane in each direction until test results confirm whether more stringent weight restrictions need to be applied.

Bridge owner Severn River Crossing has authorised the installation of temporary acoustic monitoring system next month as a fast check for wire breaks.

The old Severn Bridge was joined by a second bridge ten years ago, with combined annual traffic only 40% greater than that on the Forth Road Bridge.

High Winds? Forget It!

Bridgemaster Alastair Andrew makes a strong plea that when high wind signs are activated, drivers act responsibly and divert.

"Our responsibilities do at times require us to close the bridge to wind susceptible vehicles. When the wind gusts above 50mph, the bridge is closed to all high sided vehicles, motorcycles, caravans and cars with large roof boxes,' he explains.

"The NADICS signs throughout the central belt of Scotland carry the warning 'Forth Road Bridge closed to high vehicles' and yet many high vehicles continue to arrive at the bridge during these winds."

"Turning back vehicles at the tolls causes delay and frustration to other users. However vehicles regularly cross from the north side (no toll booths) and this puts all bridge users at risk."

"It may be inconvenient and costly to use an alternative route, but that's insignificant to the costs associated with complete closure of the bridge when a vehicle overturns,' said the bridgemaster.

Ferry Fares Not So Fair

IN the year before the FRB opened, when 800,000 vehicles of all types were transported across the Forth from South to North Queensferry piers by a fleet of four ferries, a quaint invention reared its head.

A post was positioned in the ground towards the end of the pier drive lanes which intimated that at this point drivers would be quicker going over the firth via Kincardine Bridge, ten miles up river. (Was this where Disney World cottoned on to the queuing post times idea?).

The fare charging system was also unique. A hearse for instance was ten shillings return, whereas the corpse was 12/6, one way of course. A horse (mare) was 2/6, but a stallion was 8/-. Similarly a cow travelled for a mere 1/6, but the bull's fare was five bob! Sex discrimination in 1963?