An Ideal Solution

Turkish contractor works with Italian manufacturer to create elevators for towers in the world’s fourth-largest suspension bridge.

Istanbul and Izmir: One is the heart of Turkey’s economy, trade, history and culture, the other a city of history, tourism, the sun and wind. Traversing the distance between what are, respectively, the first- and third-largest cities in Turkey, previously took an average of 9 hr. by car. That has been reduced to 3.5 hr., thanks to a new motorway that includes the Osmangazi Bridge, the world’s fourth-longest suspension bridge. The distance from one end of the bridge to the other can be covered in 6 min.

Serving this bridge are four elevators — two for freight and two for staff — manufactured by Maspero Elevatori SpA of Italy. Maspero’s track record and reputation were what prompted project manager GIIB Gebze Izmir Motorway Operation and Maintenance, Co., Inc. to turn to Maspero. Unlike in other bridges, each of the tower legs incline toward one another at 0.74˚. This was an inconvenient detail. The Osmangazi Bridge technical staff explained that this made finding a solution through conventional elevator modelings difficult for most companies. Maspero is considered a specialist in this type of elevator construction.

Opened on June 30, 2016, Osmangazi Bridge is part of the 420-km-long build-operate-transfer public/private highway project in Turkey. Foundations were laid in 2013. The Gebze-Osmangazi-Izmir (including the Izmit Gulf Pass) portion of the project consists of 377 km of highway and 44 km of linking roads.

The bridge is a 4,538-m-long span that includes the 253-m Northern Approach Viaduct between Dilovasi on the north side of the Izmit Gulf and Hersek Delta on the south, the 2,907-m-long part over water and the 1,378-m Southern Approach Viaduct. The bridge’s main span (the distance between the two towers) stretches 1,550 m.

Planned to have a service life of 100 years, the bridge’s maintenance needs were carefully studied, even during the design stage. It was designed to provide high comfort and quality, and built according to European norms to meet all highway technical requirements.

Unlike those of the Bosporus Bridge, the towers of the Osmangazi Bridge were built in the sea, because the bridge is much longer than the one over the Bosporus Strait. Rising 252 m from the water’s surface, the towers are almost as tall as Istanbul Sapphire, the tallest building in Turkey at 264 m.

The freight and passenger elevators serving the Osmangazi Bridge towers have capacities of 2000 kg and 750 kg (or five to six people), respectively. The cabins of the freight elevators are 2 m2, 1.5 m deep, 1.35 m wide and 2.2 m tall. The cabins of the passenger elevators are 1.05 m2, 0.9 m deep, 1.20 m wide and 2.2 m tall.

With six stops, all elevators operate from a lower height of approximately 235 m (10 m above the sea’s surface) up to 245 m. The maximum speed is 2.5 mps, and doors are fire rated. They have an audible and visual overload-warning system. The main functions of the elevators are operated manually. Fully automatic programmable logic controller connections have been in use since August.

Designed while considering all safety precautions, the elevators are equipped with overload sensors, audible fire detectors, CCTV cameras and emergency phones. They are also equipped with an emergency brake that can be controlled from inside the cabin. With sufficient illumination and air-conditioning, the passenger cabins offer a comfortable atmosphere for both guests and bridge workers.

Routine inspections and maintenance will be performed during the periods specified by the Suspension Bridges Management Manual and as recommended by the manufacturer in accordance with the relevant regulation provisions and approvals by authorized institutions.

Together with the elevator subcontractors with which they have worked since the earliest manufacturing phase, GIIB and Maspero oversaw the installation every step of the way and now have a vertical-transportation system of which they can be proud.