How long can a wooden bridge get?

Wood has been and is still used for long span bridges in Scandinavia and the US. They are often covered to provide additional weather protection to the structural timbers. In the UK we are more conservative and tend to go to steel for the load bearing elements at shorter spans. The most commonly required bridges are less than 15m for pedestrian and cyclist users. Wood is the most economical solution up to about 8m span. Once this length is exceeded the size of the sections required and their availability in timber of the quality required are deterrents. The Bridge En...
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What is Ekki?

Ekki is the most popular hardwood used for making bridges. It comes from The Gabon in West Africa but is usually sourced via Holland. A Francophone nation – interesting fusion of African and French cultures! It is a Tropical Hardwood. It is however grown in accordance with the Forestry Stewardship Council processes and is FSC Certified. There are ethical issues to do with the carbon used to deliver the material to Europe. The oil used in marine transportation is the dirtiest and most polluting – used by shippers because it is cheap. It is suspected that virgin f...
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Why have cranked parapets?

Why have cranked parapets? People are not the same width. Their width at ankle level is small. They get wider at Hip Height and maximum width at shoulder level  particularly if carrying a rucksack. Narrower decks have lighter loads and can have smaller beams Unfortunately the posts taper and are weakened especially the coring strength of the wood near the fixings We can offset this by using wider washers or plates.      
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What are the best fixings for wooden deck boards?

What are the best fixings for wooden deck boards? When fixing Deck Boards we need to ensure they are securely fastened down and that they cannot be easily removed by vandals. However we also need to make it possible for the deck boards to be lifted (by authorized people) in order to inspect the bridge at regular intervals and if necessary to be able to repair or maintain it. Wooden deck boards are invariably fastened to timber. This will either be wooden beams or wooden Stringers fastened to the top of steel beams. It is important that these stringers are not damaged by the fixing....
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Why have parapets?

Why have parapets? Parapets are provided to prevent users form falling from the bridge. If you provide them it indicates you recognise the hazard.  The question then arises if one parapet is sufficient? In some locations there would be no injury and in others the fall could be fatal The User Type is an issue. Small active children can get through or climb on a parapet leading to a possible incident. In some locations when danger is high a 100mm sphere should not pass through any opening. The parapet height is intended to prevent a person falling ov...
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Kick Boards

On scaffolds, on building sites, kick boards are quite rightly mandatory. They prevent tools or materials being knocked off to fall on people working below. When bridges cross rivers this is not relevant When bridges cross other paths it is good practice but is not always observed. If the kick board is in direct contact with the deck it will trap debris. Soil will build up and plants establish. The combined effect will keep the wood permanently wet and the life of the timber will be reduced, On equestrian bridges The British Horse Society recommends high kick boards -&n...
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Boardwalks are a blessing

As a measure to protect sensitive environments, prevent erosion and make it practical for members of the public to enjoy wild spaces, without feeling at risk, boardwalks are the solution. They can be used on the coast, in moorland, march, mountain or farmland. In some locations they are highly seductive and draw people away from the hubbub of life into wild and special places. They provide a proximity and intimacy with the environment without comparison. Less mobile people feel secure on them, provided they are correctly designed and are structurally sound. Small k...
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Why are Kit Bridges so popular?

Building a kit bridge brings a community together. Shared memories and a sense ownership of the bridge appeals across the ages.   IKEA has taught us all how to follow instructions and each kit is supplied with detailed instructions. If there is any nervousness we can supply a Supervisor to either offer advice or to organize the job. Volunteer Groups can supply and install a bridge and make it affordable After the recent floods there are many site which need new bridges and the local authorities lack the funds to pay for them. Community Action is often the only alte...
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Anti Slip Treatment

Bridge users regularly slip when surveying older bridges. It is only their agility which saves the day Leaf litter, algal growth, dog-mess and dampness can reduce untreated decks to an ice rink. Especially on hardwood decks. The introduction of grooving was a great help Clearly grooves are only effective if they are not over laid with litter, As anti slip treatments became available the question of the most effective use of it arose. In the first instance the material was spread across the entire surface and before it cured aggregate was sprinkled onto it. Handling t...
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What is cladding on a bridge?

Occasionally we are asked to make a bridge with steel beams look like a timber one. It Surprises us how people feel galvanized steel finish is out of place in the countryside. virtually every field gate and kissing gate is galvanized. We don't have these feelings as Engineers. Ever eager to supply what our clients want, we naturally conceal the beams. This process is called cladding.   in order to inspect the bridge, the cladding needs to be capable of being removed. This can be a costly process involving scaffolds and the disturbance of wildlife (bats). B...
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