When Russia annexed Crimea from Ukraine in 2014 it created an international outcry, but it also faced an immediate need to connect the new territory to the motherland. Now Russian engineers are throwing up a £2.5bn road and rail bridge across the Kerch Strait.
Vladimir Vladimirovich Putin is not known as a bridge builder in international relations. In recent years Russia’s all-action president has been associated with bold – some would say illegal – international actions including his country’s military involved in Syria and the Ukraine.
But burning bridges on the diplomatic stage means – strangely enough – building bridges in the real world.
When Russia annexed Crimea from Ukraine in 2014 the government was faced with an immediate problem. The only land connection to Russia proper runs through Ukraine and its still disputed eastern Donbass region.
“From a strictly economic perspective, Crimea is actually more of a burden to Russia, as evidenced by the major infrastructure projects necessary to circumvent its continued dependence on transportation and energy links through Ukraine, including new power lines and power plants,” says Kevork Oskanian, a research fellow at the University of Birmingham’s Centre for Russian, European and Eurasian Studies.
“As [with] most of the rest of Ukraine, it is also considerably less affluent than Russia, and bringing pensions and public sector wages up to Russian standards has therefore also been a drain on Moscow’s resources, as has an annual subsidy to the local budget of about $1.5bn (£1.1bn),” he adds.
The new Russians in Crimea face a less than sympathetic route to their home markets.
So the race is on to build a 19km bridge across the Kerch Strait. And like the Stakhanovite workers in Stalin’s Russia who promised to “complete the five-year plan in three” the objective is fast completion – a two year construction programme.
The crossing will be known as the Krymsky Bridge (Crimean Bridge) – not to be confused with another crossing with the same name in central Moscow.
If all goes according to plan, the bridge will open to road traffic in December 2018 and to rail traffic in 2019.
The dual road-rail bridge will carry four traffic lanes and two rail tracks. It begins on the Taman Penninsula and uses a 5km dam section and the Tuzla Spit.
A panel assessed 74 route options, and decided that the southern route across the Tuzla Spit was preferable. This is in fact a longer distance to cover than the next most favoured route, which would have started from the Chushka Spit in the north.
Route Options: Chushka Spit Vs. Tuzla Spit
|Chushka route||Tuzla route|
|Would paralyze ferry traffic between Port Crimea and Port Caucasus||Better roads|
|Mud volcanoes would impede construction||Avoids historic sites|
|Requires motorway and rail bypasses||Space for construction sites|
|Water wells located nearby||Shorters access roads|
|Many historical landmarks on route||Does not interrupt ferry traffic|
|Slopes facing Crimea are prone to landslides||Allows choice of installation techniques for infrastructure|
|Strait may feeeze in winter|
Maritime navigation in the Black Sea is a crucial consideration for the bridge.
“The Sevastopol naval base – HQ of Russia’s Black Sea fleet – is, without doubt, Moscow’s main strategic asset within Crimea. It was probably the main reason why the peninsula was taken over by Putin’s forces in the first place. The presence of, for instance, considerable natural gas reserves (potentially up to 2.3 trillion m3) in the waters around the region would only have paid a minor part in the decision,” says Oskanian.
So the bridge incorporates a 227m span arched section with 35m clearance for shipping.
This visualisation of the completed bridge shows the navigable pass for shipping. [Source: Крымский мост/Krymsky Bridge]
During the construction work, buoys have been deployed to mark the navigation path on the Kerch-Yenikal channel, each buoy is visible between 3.6km and 5.4km. Waters around the construction area are off-limits to shipping – except for Russian naval vessels.
While a modern conflict continues in the Ukraine, the engineers on the Kerch Strait Bridge have dealt with the aftermath of heavy fighting in the area during past conflicts.
The project identified and defused more than 700 explosives – including 14 aerial bombs – during preparation work for construction.
Geology has dicatated that piles for the bridges are to be driven to a depth equal to a 30-storey building to penetrate a thick silt layer and reach the solid soil beneath.
“Underneath it, there is hard clay, suitable for holding a bridge. But to get to this solid ground, we need to drive our piles 30m to 94m deep,” says Leonid Ryzhenkin, director for construction with Stroygazmontazh, the contractor on the project.
“The findings and recommendations offered by scientists were taken into consideration when designing the Krymsky Bridge. They factored in our choice of pile types for bridge pier foundations. As a result, we are now inserting more than 7,000 piles of three types: bored piles, prism-tipped piles and tubular piles. In areas that have the most challenging geological profiles, 1,420mm diameter steel tube piles are inserted, as this type of pile can be driven down as deep as 94m,” says Ryzhenkin.
Seismic activity in the area is a further consideration and this influence the decision to use vertical and inclined piles installed on the project.
“Once every few thousand years, the Kerch Strait may experience an earthquake with a magnitude of up to 9. That is a tiny possibility, but the architects of the bridge have made room for it, too. To make the bridge more earthquake-resistant, we insert tube piles into the ground not only vertically, but also at an angle. So every bridge pier effectively sits on a sheaf, or a bush of piles, if you will,” says Ryzhenkin.
The rail bridge comprises 307 piers, and is supported by more than 3,000 piles while the road bridge has 288 piers and 2,500 piles.
Tubular steel piles with concrete cores will be sunk to 5m into the seabed to provide the foundation for the piers. Rail bridge foundations also include prism-tipped 400mm by 400mm reinforced concrete driven piles.
“Thanks to elaborate planning and careful site preparation, we have been able to launch construction simultaneously from several sites located on and offshore. We are effectively building the bridge all along its length at the same time,” says Ryzhenkin.
“Integrated construction systems are employed for installing the superstructure, each equipped with an assortment of construction machinery for inserting piles at varying depths, laying grillages and building bridge piers. Using such complexes enables us to minimise the use of floating cranes and other special-purpose vessels that cannot be effectively used during a storm,” he adds.
Floating crane use has been minimised to help speed the project. [Source: Крымский мост/Krymsky Bridge]
The exception will be the bridge’s Ozero and Kerch stretches where bored cast-insitu piles made from heavy hydraulic concrete with steel reinforcement are to be used.
Heavy storms and ice formation in the Black Sea mean that the bridge are other design considerations. The Krylov State Research Center constructed a 1:50 3D-printed model to test how the bridge design would withstand wind speeds up to 56m/s. The centre also conducted an ice test in a swimming pool that featured floating ice floes and hummocks.
“Three temporary bridges that have been thrown across the Kerch Strait to transport workers, hardware and construction supplies to offshore construction sites, and to enable a variety of technical operations, even when there is a storm. In other words, the temporary bridges give us an opportunity to continue working on the main bridge in any weather,” says Ryzhenkin.
The temporary bridges are designed to carry mobile cranes and can take loads up 250t. Piling rigs and other heavy vehicles also use these structures.
“The first temporary bridge links Tuzla Island to the Taman shore. It is more than 1km long, and rests on 58 bridge piers, their piles sunk up to 56m deep. It takes a five minute drive or a 15 minute walk to cross it,” adds Ryzhenkin.
“The other two temporary bridges stretch toward one another from the city of Kerch and from Tuzla Island, respectively. The temporary bridges do not cross the navigable Kerch-Yenikale Channel, and therefore do not obstruct maritime traffic between the Black and the Azov Seas.”
“We have been able to keep up a fairly good rate of progress thanks to extensive preparation. In the run-up to the launch of construction in February 2016, a great deal of preparatory work was carried out throughout the year 2015 on both shores of the Kerch Strait, as well as off-shore,” says Ryzhenkin.
The rail bridge comprises 307 piers, and is supported by more than 3,000 piles while the road bridge has 288 piers and 2,500 piles. [Source: Крымский мост/Krymsky Bridge]
“Equipment was also examined and selected in advance. For example, to ensure maximum efficiency, we use pile driving rigs that have multi-tier pile guide frames, as well as pile drivers with tall masts that can insert piles of up to 80m in length. They use piles that consist of several steel tubes welded together through electric arc welding,” he adds.
Crimea was conquered for the Russian Empire in the 18th Century and it has played an important role in Russian and world history.
It provided a summer residence for the Tsars, and hosted the Yalta Conference where the great powers divided the spoils from World War II.
When the Kerch Strait is bridged, the Crimean Peninsula will become a little more bound to Russian history – whether Western powers like it or not.