A T ELSA RíOS GONZÁLEZ’S hair salon in Atenco, east of Mexico City, the chatter turns to the most controversial issue in town, the construction of an international airport. Mexico’s biggest infrastructure project, known as NAICM , is being built just a few kilometres away. Opinion in Atenco is divided. Some of Ms Ríos’s clients fret about the noise and pollution the airport will bring. Others hope for riches. “No one is well informed enough” to judge its merits, says the hairdresser.

Andrés Manuel López Obrador, who will become Mexico’s president on December 1st, disagrees. A longtime foe of the project, he has put its fate in the hands of voters through a referendum-like “consulta”, to be held on October 25th-28th, more than a month before he takes office. How this unorthodox plan turns out will reveal much about what promises to be an unorthodox presidency. A veteran populist, Mr López Obrador portrays himself as an instrument of the will of ordinary Mexicans. He will offer them an opportunity to vote him out of office midway through his six-year term. The airport consulta is a preview of the sort of direct democracy that he says will characterise his administration.

As mayor of Mexico City from 2000 to 2005, Mr López Obrador sent survey-takers door to door to find out what people thought of his initiatives. He was fishing for the answers he wanted, some said. His first presidential foray into popular democracy will be more contentious. Unlike recent votes on airports in Berlin and in Nantes in France, the consulta does not just test opinion of citizens in the vicinity. It will be organised by Mr López Obrador’s inner circle, not by the national electoral institute ( INE ). Activists from Mr López Obrador’s Morena party will set up and monitor 1,073 booths in about 500 municipalities, home to 80% of the population. Just 1m ballot papers will be printed for a nationwide electorate of 90m people. They will be counted by a little-known NGO . Without access to the INE ’s electoral rolls, it is unclear how the poll workers will prevent people from voting more than once.

Participants will be asked to choose whether to press on with construction of the X -shaped airport, which is already 30% completed, or to scrap it. The alternative is to supplement the existing airport with a new one at the Santa Lucía military airbase north of Mexico City. Mr López Obrador says the result will be binding, whatever the turnout.

Few doubt that something must be done. The capital’s airport, the busiest in Latin America, handles 50% more people than it was designed to do. It has no space to expand. The number of passengers is growing by nearly 10% a year. The boggy land near Atenco is one of the few areas available for a replacement. Vicente Fox, Mexico’s president from 2000 to 2006, tried to buy land cheaply on the east side of the area from farmers, who protested with machetes. In 2014 the current president, Enrique Peña Nieto, said the airport would be built on the western side, on land owned by the federal government.

Half-baked ideas

It would eventually serve 120m passengers a year, more than any other airport in the world today and treble the capacity of the capital’s existing airport. Its backers say it will attract firms that might otherwise make Panama or Brazil their Latin American hubs and bring jobs to the capital’s poor eastern districts. If Mr López Obrador cancels NAICM , which was designed by Norman Foster, a British architect, and is being built by a company controlled by Carlos Slim, Mexico’s richest man, he will unnerve investors whose confidence he has tried hard to secure.

But the project has been criticised from its inception. It will imperil 100,000 migratory birds that alight in the area and, critics contend, cause more flooding in flood-prone eastern Mexico City. Two-thirds of Mexicans have never been on a plane. That makes the airport look to some like a bauble for the rich. The 285bn-peso ($15bn) price tag is 70% higher than the government originally budgeted.

These shortcomings are the result of Mexico’s slapdash process for planning and approving big projects. Developers rarely consult residents who will be affected by them or publish information on subcontractors. Although contracts to build NAICM were awarded in a transparent way, the companies that secured them are not required to report regularly on their progress. That feeds a suspicion that cost overruns are the result of corruption. The government published only an executive summary of its report on the airport’s environmental impact.

Such problems are compounded by politics. Mexican presidents, who serve just one term, rush to build pet projects, or at least to make enough progress that their successors are obliged to complete them. Construction often starts before blueprints are final. NAICM ’s perimeter wall started going up before builders knew where the airport’s entrance was; they had to make expensive changes. Agencies responsible for projects often do not talk to each other. Mexico’s shoddy procedures bedevil infrastructure projects of all descriptions, including line 12 of Mexico City’s metro and a planned drainage tunnel for the capital. “The problem is not the cake, it’s the oven,” says Mariana Campos of México Evalúa, a think-tank.

In the case of NAICM , Mr López Obrador says he prefers a different cake. Repurposing the Santa Lucía airbase is the sort of low-budget, low-impact alternative that appeals to the ostentatiously austere president-elect. But the new cake has problems. Santa Lucía is farther from the city centre than NAICM . Some passengers would have to transfer to a different airport to catch connecting flights. Planes landing at and leaving the two airports, all of which must pass through the same corridor in the city’s north-west, risk colliding. That is “a safety issue that the Mexican authorities would surely never allow”, says Bernardo Lisker of MITRE , an institute that studies air traffic.

That decision now will supposedly be made by the people. Polls suggest that Mexicans favour completing the new airport by two to one, but the consulta may not reflect that. As few as 100,000 people will participate, some analysts believe. Ms Ríos, who wants construction to continue, plans to stay home. A determined get-out-the-vote effort in one corner of the country could swing the result. Some observers suspect that Mr López Obrador is engineering a vote in favour of NAICM , giving him an excuse to complete a project that he claims to oppose but would be difficult to abandon.