Two girls sit on a swing set, their enormous smiles offsetting the disturbing scenery behind them – miles of highways surrounding their homes. Like 9 out of 10 of Istanbul’s citizens, their family doesn’t own a car. One girl explains, “There is a road, but there is no transportation. There are no buses – the municipality doesn’t provide them.”

This powerful scene is one of many in Aslihan Unaldi’s full-length documentary Overdrive, to be featured at the Urb4nize festival next week. The film tells the story of Istanbul’s accelerated population growth and car-centric policies, which have deepened inequalities between those who drive, and those who don’t.

Since the film’s release in 2011, Istanbul has made strides towards improving public transport. But the challenges Istanbul faces in the film are not unique to Turkey. Population growth and debilitating congestion are problems confronting developing cities on every continent, as municipalities struggle to reconcile decades of car-centric development with the needs of their citizens.

One solution, which 160 cities around the globe – including Istanbul – have turned to, is to build a bus rapid transit system. Cheaper to implement than a metro, but similarly effective at moving passengers across the city, BRT systems offer relief for cities which previously lacked high quality public transport.

In 2011, Istanbul was just beginning to ramp up its BRT. The expanded BRT, the third leg of which was launched in 2012, is now one of the more heavily used advanced bus systems in the world, serving 800,000 passengers daily.

Istanbul’s BRT and other efforts to provide public transport, including improving the network of bike paths across the city, have improved the situation since the film was made in 2011. However, the message of “Overdrive” is still relevant. By sharing the stories of those who deal with the inequity of transport every day, the film puts a human face on an issue that can sometimes feel too broad or abstract. If you don’t own a car in these cities, you don’t have access to a job; you don’t have access to education. This reinforces the detrimental notion that the car should be a status symbol.

Transport is not just about moving faster, or even how you move. It’s not just about replacing the car. It’s about giving access to people. It’s about equality. This movie explores the extreme inequality faced by those without access to good, reliable transport. In the trailer for the film, a Turkish woman confesses to the camera that she spends six hours a day on transport. “Can be more,” she adds.

Lack of access is a problem that pervades cities around the world. Though transport options – such as advanced bus systems – are rapidly expanding, we have to consider the two girls on the swings from Overdrive. They live in Sultanbeyli, a neighborhood of 1 million residents on the Asian side of Istanbul. Their home is next to the Trans-European Motorway, one of the biggest expressways in the city. They are not connected to the BRT. The bus they take is often so crowded, the doors break.

So long as we build cities to move cars instead of people, there will be inequality of access. With millions of citizens wasting several hours a day on poor public transport, it is impossible for developing cities to realize their full economic potential. Citizens without a car will be marginalized, trapped, and undervalued until we build our cities so that all citizens can bicycle, walk, or ride the bus with ease.

Overdrive – Produced in 2011 by EMBARQ – will be screening this October at the Urb4nize festival in Vienna, a ten day affair running October 4 – 13. The festival seeks to celebrate and discuss ways to build ideal cities.