Pittsburgh has a relatively concentrated downtown -- the distance between Firstside Park on the southern border and the David Lawrence Convention Center that hugs the Allegheny River is less than 1 mile.

Director of Mobility and Infrastructure Karina Ricks said Pittsburgh can become a city where walking and biking are the de facto modes of transportation for short distances. Currently, 30 percent of car rides in Pittsburgh are 1 mile or less, according to Ricks.

But for people with limited mobility, or as a warmer option in the winter months, Ricks says ride sharing could be an integral part of sustainable transportation in the city. She says the city is in the beginning stages of working with services including Uber and Lyft to ease congestion and reduce environmental impact.

"We're working toward establishing a partnership," she said. "Working toward really having initiatives and measurements and programs that would create a closer working relationship than has ever really existed."

Officials with Uber confirmed that the company is in talks with the city, saying in a statement, "We are in active conversations with the city on a number of initiatives to address their mobility challenges, and we are eager to continue partnering with other local leaders and nonprofits to benefit Pittsburgh."

Neither the city, nor Uber offered specifics on what the partnership will entail. However, Uber officials said the company plans to collaborate with the city on mobility, environmental issues and education. The company plans to announce more on these ventures in the coming months.

Since Uber began testing its autonomous vehicles in Pittsburgh last year, the relationship between the company and the city has sometimes been tense.

Ricks' vision for sustainable Pittsburgh transportation consolidates the number of bodies per car, so there are fewer trips that serve only one person. This would take up less space on the roads and create fewer emissions.

For a city that already has 259,000 active Uber riders, ride sharing services could be a way to promote this way of traveling, according to Ricks. Uber already has an option to carpool, called UberPOOL, but it's not yet available in Pittsburgh.

"We want to work with these companies, and we're actually having a renewed conversation with them as to how ride sharing services can actually help fulfill city goals," Ricks said.

Earlier this year, the city unveiled a list of ambitious environmental goals to be met by 2030. One of these is to reduce emissions city-wide by 50 percent.