VANCOUVER is the best place to live in the Americas, according to a quality-of-life ranking published earlier this month by Mercer, a consulting firm. The city regularly tops such indices, thanks to its clean air, spacious homes and weekend possibilities of sailing and skiing. But its status as an urban oasis is threatened by worsening congestion. Over the next three decades, another 1m residents are expected to live in the Greater Vancouver region, adding more cars, bicycles and lorries to roads that are already struggling to serve the existing 2.3m residents.

A proposal by Vancouver’s mayor and 20 of the 22 other local governments in the region seeks to avert the snarl-up. Upgrades would be made to 2,300 kilometres (1,400 miles) of road lanes, as well as bus routes and cycle paths. Four hundred new buses would join the fleet of 1,830. There would be more trains and more “seabus” ferry crossings between Vancouver and its wealthy northern suburbs. The catch: to get all that, residents must vote in a referendum to accept a hike in sales tax, from 7% to 7.5%. Polls suggest they will vote no.

Everyone agrees that a more efficient transit system is needed. Hemmed in by mountains to the north, the United States to the south and the Pacific Ocean to the west, Vancouver has sprawled in the only direction where there is still land, into the Fraser Valley, which just a few decades ago was mostly farmland. Highway 7 winds eastward through shopping centres in the suburbs of Burnaby and Coquitlam, and into the residential neighbourhoods of Pitt Meadows and Maple Ridge. The road is often clogged. Signs tout high-rise apartments and condos under construction, telling drivers that they could be home by now if only they weren’t stuck in their cars on a slow-moving highway.

Yet commuters’ suspicion of local bureaucrats may trump their dislike of congestion. TransLink, which runs public transport in the region, is unloved by taxpayers. Passengers blame it when Skytrain, the light-rail system, stalls because of mechanical or electrical faults, as happened twice in one week last summer, leaving commuters stuck in carriages with nothing to do but vent their anger on Twitter. TransLink’s boss, Ian Jarvis, was ousted early in the referendum campaign, only to be kept on as a consultant earning C$35,000 ($28,000) a month.

That sort of thing has made voters less willing to fork out the C$7.5 billion in capital spending that the ten-year transit upgrade would involve. Gregor Robertson, Vancouver’s left-leaning mayor, acknowledges that the plan is a hard sell. “Generally people don’t opt in for paying more taxes. It’s a difficult question to pose to citizens and it doesn’t always succeed unless a really strong case is made,” he says. He is running out of time to make it. Postal ballots went out earlier this month, and voters have until May 29th to return them.

A coalition of trade associations, labour unions and environmental groups is hoping to turn the tide. Despite the complaints, Vancouver’s transit system is a decent, well-integrated one on which to build, reckons Todd Litman, a transport consultant who has worked for TransLink. “These upgrades are all-important if Vancouver wants to maintain its reputation for being a destination others want to go to,” he says. If congestion worsens, the city may slip down the liveability rankings, attracting fewer new residents. At least that might mitigate the traffic problem.