The construction company OHL Concesiones opened the M12 toll motorway in 2005 after investing €380 million in anticipation of a surge in traffic from the fourth terminal being built at the airport.
Almost ten years later, the expected rise in numbers has failed to occur and OHL has found itself filing for bankruptcy after declaring total debts of over €550m.
The company cited 'construction and compulsory purchasing costs significantly higher than those predicted' and 'extraordinarily low' traffic volume as factors in the initial filing in November last year which was completed this week.
Only 7,200 vehicles per day use the road, many of them because they have become lost as a result of the poor signposting.
Forecasts predicted that up to 50,000 vehicles would use the M12 every day despite the presence of an alternative, and free, major trunk road running alongside it.
The lonely road to Barajas has topped Spain's list of costly infrastructure flops and fiascos, according to national daily El Pais.
Other disastrous civil engineering projects include the 'empty airports' at Ciudad Real (€450m), Castellón (€190m) and Murcia (€200m), commissioned during the pre-crisis boom years.
The M12 may have been deserted by drivers but finds itself in plenty of company in the insolvency courts.
More than €4 billion in debts from failed toll roads have been declared in Madrid.