Severn Bridge

Bridging the technology gap

Far more goes into our bridging technology under the surface than we realise and when the bridges are spanning sizeable widths and at height, the upkeep and maintenance is significant and a routine schedule of works a necessity. The Humber Bridge, near Kingston Upon Hull is 2,200m long, that’s just over 7,000 feet of road surface that needs maintaining on a regular basis. Road surface condition is important on normal roads, but when there is an increased risk of danger, then it goes from important to imperative. Hitting a pothole and slewing into a safety barrier can take on a whole new dimension when that barrier is all there is between you and a steep plummet into the void below.

Bridges such as the Humber bridge and the Severn bridge span huge distances, suspended above busy waterways often 130-160m up. If there were to be an accident, then any form of recovery suddenly becomes an intensive task that can have devastating effects not only on the flow of traffic on the bridge, but also at either side, and even across the shipping channels or the terrain down below.

Early warning markers are vital for bridge deck repair

High winds, disorientation and poor lane discipline coming out of  or heading into toll gates, can all make bridges higher-risk areas for motorists regardless of any potential threats posed by uneven road surfaces, cracks and potholes. Indeed, there are special warning measures built into the surfacing on bridges to ensure that repairs are flagged and dealt with immediately. When the surface asphalt becomes damaged or worn on bridges such as the Humber and the Severn, a dense layer of red asphalt suddenly becomes visible as a warning marker. Once this red asphalt is able to be seen, it is time to repair the surface quickly and render the bridge safe for motorists again. Although a vital warning sign, pouring this dense layer of red asphalt like a carpet across the length and breadth of the bridge under the surface, can be costly, time- consuming, labour-intensive and even add to the weight of the bridge.

High visibility and waterproofing for safety

Today’s advances in asphalt technology in the GlasGrid® geosynthetic product range, however, negate the need for this thick red warning layer. Instead, a lighter ‘indicator’ mesh, also coloured red, can be laid easily beneath the surface layer. Once this mesh becomes visible, then it is time the road is repaired. The alarm system, the warning mechanism is the same, and the benefits far greater. This mesh has the advantages of being environmentally-friendly, being of high-tensile strength, durable, light and still providing the necessary warning mechanism. It is also lighter, faster to install, self-adhesive and provides a strong bond between the surfacing layers and protection for the waterproofing layer. Effective waterproofing is paramount in safe, durable pavement resurfacing and preventing water ingress into the lower layers of the pavement structure prevents the onset of reflective cracking further down the line. Faster to lay, it means a faster turnaround repair time for getting traffic back on the bridge and onward to where they need to be with minimal disruption. A faster, slicker more user-friendly process all round that makes using this technology hugely beneficial to the logistics of modern bridge building and the most important part of all – safety.