Turkish President Recep Tayyip Erdogan on Tuesday opened a new road tunnel underneath the Bosphorus in Istanbul, the latest in a string of ambitious schemes to transform the country's infrastructure.

Erdogan, who has dominated the country from 2003 first as premier and then head of state since 2014, boasts that such undertakings are his "crazy projects" that no other Turkish leader had dared dream of.

From bridges to a shipping canal and airports, here is a rundown of the projects whose completion Erdogan has overseen and those still in progress.

MARMARAY TUNNEL

Opening date: October 2013

The Marmaray Tunnel was the first ever undersea passage beneath the Bosphorus between Europe and Asia. It is used by a suburban train system linked to Istanbul's metro network. According to the authorities, it has so far transported 172 million passengers.

OSMAN GAZI BRIDGE

Opening date: June 2016

The fourth-longest suspension bridge in the world, the Osman Gazi bridge stretches 2.6 kilometres (1.6 miles) across the Izmit gulf in Turkey's industrial northwest. It is named after the founder and first ruler of the Ottoman Empire.

SULTAN SELIM THE GRIM BRIDGE

Opening date: August 2016

A hybrid between a suspension and cable-stayed bridge, the Sultan Selim the Grim bridge is the widest suspension bridge in the world at 58.5 metres (192 feet). It is the third bridge across the Bosphorus, after the first opened in 1973 and the second in 1988. It is named after the 16th century sultan who conquered swathes of the Middle East during his eight-year rule.

AVRASYA TUNNEL

Opening date: December 20, 2016

The bridge is the first ever road tunnel underneath the Bosphorus Strait in Istanbul and has been built at a depth of 106 metres (348 feet). The total tunnel project comprises an undersea Bosphorus crossing 3.4 kilometres (2.1 miles) long. The authorities are now considering building a third tunnel in Istanbul to take trains and vehicles.

ISTANBUL NEW AIRPORT

Opening date: February 26, 2018

Work on the new Istanbul airport is already well advanced. Built by the Black Sea, well outside the city centre, the authorities hope that the size of the facility will make Istanbul a global aviation hub like Dubai. Campaigners however accuse the authorities of ruining one of the few remaining green areas outside the city.

CANAL ISTANBUL

Opening date: Unspecified

Possibly the most ambitious of all of Erdogan's projects, the Canal Istanbul envisages the dredging of a new canal from the Sea of Marmara to the Black Sea, aiming to take pressure off the Bosphorus, one of the world's busiest shipping bottlenecks. The authorities have dismissed suggestions the Panama or Suez-style project is a step too far and Erdogan has said tenders will start in 2017.

DARDANELLES BRIDGE

Opening date: 2023

The bridge will span the famous Dardanelles Straits off the Gallipoli peninsula in a project that would dwarf the bridges over the Bosphorus. Erdogan has said construction will start on March 18. The area has huge national significance for Turks as the place where Ottoman troops resisted invading Allied soldiers in World War I. It is expected to be called 1915 Bridge after the year of the campaign.