One race that looks like it will go down to the wire before the London Olympics have even begun is Mayor Boris Johnson's bid to link both sides of the Thames by cable car in time for the official opening ceremony on 27 July.

The logistics of such an ambitious project have proved rather a marathon, peppered with many obstacles en route, not to mention false starts; and while the vast majority of the Olympic infrastructure has been completed well ahead of schedule, this is one scheme destined for a sprint finish.

On paper, the idea is brilliant: provide both a tourist attraction and a new commuter route that connects the area around The O2 Arena on Greenwich Peninsula to the Royal Docks near the ExCeL Centre on the other side of the Thames; not by a run-of-the-mill bridge or tunnel, but by a futuristic cable car which will not only underline London as a city of ground-breaking and innovative architecture, but also provide passengers with some of the most striking aerial views of the Olympic Park and city.

Of course, in practice things have proven rather more difficult. An initial expected outlay of £35m has nearly doubled to an estimated total cost of £60m – making it the most expensive cable car system ever built. This threw a major spanner in the works for Boris, who had always promised no public funding would be needed for the project.

One of the reasons for the spiralling costs was an underestimation of the amount needed for legal advice, project management and land acquisition. After all, with City Airport so nearby, this will be the only cable car system in the world to cut through an airport's "Crash Zone".

It's just as well Emirates have stepped onboard as the cable car's sponsor: the Dubai-based air carrier will cover £36m of the total costs on an initial 10-year sponsorship deal that will see the Thames gondola link officially called the Emirates AirLine (see what they've done there?).

Although the scheme was announced in July 2010, construction only got underway in August 2011 – prompting fears that the project would not be completed until after the Olympic Games.

Construction was completed in mid May at a cost of £45m but important safety tests still need to be done to guarantee a pre-Olympic opening date.

Recently re-elected and full of beans, Boris stressed that the speed in which the construction of the cable car was completed was a "clear demonstration of London's ability to deliver world class projects and attract major investment".

But the Mayor conceded the Emirates AirLine may not be ready to carry passengers in time for the Games, saying he would "not make promises of commitments" about its completion.

Despite the route already appearing on new tube maps, operation manager Danny Price said: "It was never part of the Olympic travel plan. But we always said we'd be aiming to be open for summer 2012 and that's very much the case. Testing will take as long as it needs to. The absolute priority is delivering a safe and reliable service."

Meanwhile, critics of the project continue to label it as a mayoral vanity project and highly expensive tourist attraction – opposed to a much-needed river crossing.

However, should Boris silence the dissenting riff-raff in time for the whiff-whaff, then visitors to the greatest sporting show on earth will have even more reason to be wowed by what London has to offer.

Essentially, the cable car will link the North Greenwich Arena, which hosts the London 2012 gymnastic, trampoline and basketball events, to the ExCeL Centre, home to the Olympic boxing, fencing, table tennis, martial arts and wrestling events, plus a whole hosts of Paralympic events.

The cable car – similar to New York's Roosevelt Island Tramway, the Cologne Cable Car and the Caracas Aerial Tramway – will also help link both the Tube and London River Services to the Docklands Light Railway. It will transport an estimated 2,500 passengers per hour in each direction (the equivalent of 50 buses) and be accessible with an ever-trusty Oyster Card (ticket prices yet to be confirmed). The cars will also have retractable benches to fit bikes inside.

But the Emirates AirLine will be so much more than a mere method of transportation – it will become an attraction in its own right.

As high as the tallest part of the former Millennium Dome, the cable car project should in the years to come be as much a part of London's fabled skyline as, say, the London Eye, another airline-sponsored means of leisurely transportation.

Every 30 seconds a gondola will take passengers soaring 160 feet above the Thames on a five-minute, one-kilometre journey that will open up unprecedented views over the Olympic Park, London Docklands, Canary Wharf and the centre of London beyond.

Cost concerns aside, Londoners should be proud that such a project is taking place in their city.

If Boris can pull this one off and the Emirates AirLine is ready in time for the Olympic Opening Ceremony on 27 July 2012 then it would well be one of his biggest achievements. Regardless of its completion date, the Thames cable car will be an extraordinary legacy to London.