We may not yet be living in an age of flying cars, as predicted in the 1985 film Back To The Future II, but the rise of smartphones and other new technologies is creating a reality that is arguably as exciting and almost as far-fetched.

Experts agree that economic and demographic changes, technological advances and environmental concerns are fundamentally altering the transportation landscape. “It’s a very dynamic time,” said Robert Puentes, a senior fellow at the Brookings Institution’s Metropolitan Policy Program thinktank. “There’s a focus on a tighter connection between the role of transportation and the economic health of cities and its impact on people.”

As the average US commute lengthens and the country’s infrastructure ages badly, cities across the US are being forced to redefine what transportation is. Increasingly, urban planners, transportation experts and scientists are realizing that old auto-centric models focused on easing traffic congestion aren’t enough to tackle issues like population growth and carbon emissions, and transportation is now, more than ever, an integral component to a city’s larger sustainability efforts.

Big US cities like Los Angeles, Seattle and Chicago are working to make better use of their streets by adding more bus lanes, augmenting pedestrian walkways and expanding their rail options, while at the same time working with the private sector on advanced technologies that will allow a vehicle to drive itself and communicate with other vehicles and its environment, essentially making transportation intelligent.

“The most sustainable places to live are those places that have multi-modal transport systems,” Puentes said. “You can’t be a global competitive city if you don’t have a robust transportation network.”

Here are three of the key trends that experts predict will shape the transportation industry over the coming years.

Connectivity

The rise of ride-sharing services like Uber and Lyft – essentially taxis booked at the click of a smartphone button – and apps like Waze, which uses real-time traffic data to find the quickest routes for drivers, is dramatically changing how people get around, and affecting the very way in which traffic moves through a city.

Communication between riders and drivers, between different vehicles and between cars and infrastructure is bringing transportation into a new era, according to Allan Clelland, senior vice president at Iteris, a company developing new transportation technology.

The impact of these new apps could be broad. For one thing, ride- and car sharing could facilitate a drop in private car ownership, especially among young people, who tend to prefer using multiple modes of transportation.

According to a recent study from the UCLA’s Institute of Transportation Studies, vehicle travel has declined among millennials – individuals born roughly between the early 1980s and early 2000s – compared to previous generations. According to the study, those born in the 1990s are making 4% fewer car trips and traveling 18% fewer miles per year, on average, than members of previous generations did at the same stage in their lives.

“What we’re seeing is a tremendous willingness of the younger population to really adapt to this, to use these car sharing models as a way of avoiding car ownership,” Clelland said.

Meanwhile, those still driving cars are dealing with less traffic thanks to Waze. Experts say the traffic app has eased congestion on freeways and sped travel times for drivers, but also led to a problematic rise in cars moving through residential neighborhoods. This has angered residents, who claim the increased traffic on their quiet roads reduces their quality of life – and the real estate value of their homes – and left cities trying to figure out how to handle another entity rerouting its cars.

“You have a scenario where the government is losing control of its traffic,” said Alexandre Bayen, director of the Institute for Transportation Studies at the University of California at Berkeley.

This trend could continue as vehicle-to-vehicle data communication, as well as communication between vehicles and the surrounding infrastructure, grows. Currently, a traffic light can detect when a car is approaching, but that’s about it. Companies are working to develop technology that will enable a vehicle to tell traffic control systems not only that it is present, but also where it is going and how fast it is traveling.

For instance, a bus might be able to tell a traffic signal how many passengers it has and whether or not it is behind schedule, or a truck could communicate how big its load is and the extent of its emissions. “You can then work out algorithms that calculate what degree of priority to give the road users,” Clelland said.

Other possibilities include communication between cars and pedestrians, which could enable smartphones to alert drivers to brake in time to avoid a collision or could warn drivers about a queue in traffic around a bend. This technology is still in the formative stages, but could change how urban infrastructure is designed, according to Clelland.

Automation

Driverless cars have been in the headlines ever since Google began road testing the vehicles back in 2012. Since then, Nevada, California, Florida, Michigan and Washington DC have enacted laws governing the testing and selling of autonomous vehicles, which Google plans to bring to the market by 2020. But no one really knows when driverless cars will become commonplace.

“Some say it’s going to happen next year, then you see others say that there’s no way you’re going to have it in 10 years,” Bayen said.

But the partial automation of cars, such as with adaptive cruise control, is already underway. Bayen expects automation will progress in stages: first there might be automated buses with their own lanes – an automated bus developed by University of California at Berkeley researchers was tested in Eugene, Oregon, in 2014 – then perhaps platoons of trucks in ports or mining towns: essentially, vehicles that are connected electronically and travel in single file.

The idea of a fully automated transportation system is intriguing because it has the potential to improve safety by removing human error and increase the efficiency of car owners, who can get on with other tasks during a long commute. It can also help reduce carbon emissions and traffic congestion and allow more people access to cars, including sight impaired or other disabled persons. But even if driverless technology were ready to hit the roads now, it would take a long time to get fully automated given the average age of cars on the road is 11.5 years old, according to a July IHS survey.

“We’re gradually moving in that direction; it will creep up on us,” said Brian Taylor, director of UCLA’s Institute for Transportation Studies. “What we’re seeing is technology assisting the driver more and more.”

Environmental concern

As the world races to avoid catastrophic climate change and countries, states and cities work to meet ambitious emissions goals, these policies could also have a big impact on the future of transportation, spurring everything from zero- and low-emission vehicles to apps that encourage more walking, biking and carpooling.

Sharon Feigon, executive director of the Shared Use Mobility Center, which advocates for shared mobility like car- and bike-sharing, envisions a future where a person can use a transit pass that gives them access to numerous modes of transport in a given day. If their train is delayed, for instance, they can access a city bike, take a shuttle or rent a vehicle through a car share program using the same pass.

“We’re going to see these systems packaged together and make it as easy as possible to connect them up with each other so people can transfer seamlessly between them,” she said. “The more options people have, the more it makes it possible to reduce private car ownership.”

Redefining transportation

When considering the future of transportation, it’s also important to keep in mind why people travel: they may be headed to work, to meet friends or family or to do the shopping. Technologies and trends that reduce the need for those trips – say virtual meetings or telecommuting – could also have a big impact on transportation.

“The freeway is only an ephemeral circumstance where all cars congregate together but the purpose of travel is not the freeway, it’s when someone gets off the freeway to get to their destination,” Taylor said. “The focus should be whether or not we can enable those economic and social interactions on the other end in ways that don’t overburden the environment and society.”

There was a time when the idea of a flying car represented the height of innovation, but the technologies being imagined and developed now could be seen as even more sophisticated – and more useful in tackling the social and environmental threats that we face over the coming decades.