Bosphorus & Halic Bridges, Turkey
Bridging the Bosphorus
The Second Bosphorus Bridge (also referred to as the Fatih Sultan Mehmet Bridge) and the Haliç Bridge (also known as the Golden Horn) are two elegant, orthotropic steel deck structures in historic Istanbul that reinforce the city’s position as a strategic, cultural and economic link between Europe and Asia. The Second Bosphorus Bridge joins Europe and Asia, literally, across the narrow straits of the Bosphorus while the Haliç Bridge carries the O-1 Highway over the Golden Horn Estuary, an inlet of the Bosphorus. Between them they carry 330,000 vehicles per day; making them Europe’s busiest road bridges.
Although these bridges are iconic civil structures in their own right, their true value to both Istanbul and Turkey lies in their capability to carry a constant, uninterrupted daily flow of traffic. It was therefore critical that when it was time to waterproof and resurface the decks of both these bridges after long and effective service lives, that the system selected was not only proven to be technically superior but also, crucially, would minimise traffic disruption during the operational works.
KGM - Republic of Turkey General Directorate of Highways
ERSE Teknolojik Yapilar
- Bridging the Bosphorus
Rapid Application and Cure Minimises Disruption
The economic and environmental impact of lane closures during bridge deck refurbishment disrupting the regular traffic flow on such important links can be considerable but can be greatly reduced by selecting materials that are fast to apply, rapid-curing, durable and tolerant of difficult site and climatic conditions.
With this objective in mind and based on their previous experience of using the system on urban bridges, and the advantages it provides both during application and in its in-situ performance, KGM (the Turkish General Directorate of Highways) selected the Eliminator system for waterproofing and protecting the two bridges. To minimise disruption, a very tight 90 day schedule was set for the refurbishment of both bridges – which were to be carried out simultaneously with limited lane closures on each structure. Once on site, ERSE Teknolojik Yapilar, Stirling Lloyd’s Authorised Contractor had to remove the existing waterproofing and surfacing, prepare the steel deck and apply the Eliminator system ready for the surfacing to be laid. The Eliminator system consisted of the ZED S94 anti-corrosive primer that would not only protect the deck but would further enhance the adhesion of the subsequent membrane, the membrane itself and a final pollymer based bond/tack coat to provide a strong adhesion between the surfacing and waterproofing.
The selection of the cold, spray applied Eliminator for this and previous refurbishments realised several benefits that helped speed up the contract such as the system’s durability, speed of application and cure and the fact that it is cold-applied and simple to use. Crucially, the deck condition beneath the previously applied Eliminator waterproofing was corrosion free and so no welding was needed to replace any loss of steel section. A critical part of the refurbishment programme was an inspection of welds between deck units and stiffeners. These showed little sign of fatigue and so repairs to cracked welds were minimal.
On both bridges the system was rapidly applied using portable, simple to use airless spray equipment which gave high daily outputs. The membrane once applied, fully cured in under an hour to give a tough, durable membrane - at which point it could be trafficked, enabling contract progression and flexibility in the works programme. The unique properties of the Eliminator system in terms of tolerance of climatic conditions, ability to bond to itself and to accept full traffic after only one hour allowed other trades to access the bridge at all times. These benefits of the Eliminator waterproofing system enabled the 33,600m² deck of the Second Bosphorus Bridge and the 40,000m² deck of the Haliç Bridge to be completed in 60 days – 30 days ahead of schedule.
On these structures Eliminator proved itself to be the product of choice for urban bridges, delivering world class performance. The success of both projects was also largely attributed to the quality of the workmanship. Working in close partnership with Stirling Lloyd’s Authorised Contractor; ERSE Teknolojik Yapilar ensured the successful application of the waterproofing that enabled reduced programme times; finishing the entire project one month ahead of schedule, reducing traffic disruption and ensuring that the traffic continued to flow on two of the world’s busiest bridges.