SEATTLE (AP) — The city of Seattle is headed toward a federal court settlement that could cost millions of dollars to make sidewalks and curb ramps moreusable for people with wheelchairs and other mobility issues.

Three men with disabilities sued the city in 2015 to force the city to make upgrades. They alleged the city was violating federal law because many sidewalks didn't have curb ramps that were accessible.

The Seattle Times reports ( http://bit.ly/2otsjeS ) that many other cities have settled similar lawsuits and committed to spending more to upgrade their sidewalks and curb ramps to make them more accessible.

In court filings, the city of Seattle denied virtually all of the allegations in the lawsuit. But Mayor Ed Murray has said he iscommitted to spending more money to make upgrades.

Attorneys for all sides declined to comment on specifics of a settlement, citing the ongoing negotiations.

But in court filings in February, the attorneys wrote that they have agreement in principle on the major terms for a settlement.

Linda Dardarian, one of the plaintiffs' attorneys, told the Times that negotiations were "fruitful and ongoing," and that she hoped for a resolution by this summer.

Seattle has been working to improve sidewalks for people with disabilities even as settlement talks are ongoing.

The city hired a consultant to study more than 28,000 curb ramps in the Seattle. The $666,000 report last year mapped the condition andpresence of curb ramps throughout the city.

Seattle is building 500 to 1,000 curb ramps per year, according to Mike Shaw, the city's department of transportation's ADA coordinator.

The $930 million Move Seattle levy, approved by voters in 2015, aims to build 250 blocks of new sidewalks by 2024, with corresponding ramp construction and additional ramp repairs.

Still, there are somewhere around 40,000 sidewalk ends throughout the city that do not have curb ramps, Shaw said. That number includes intersections that may not need ramps because they're not pedestrian crossings. SDOT, citing ongoing litigation, declined to give a precise number on how many curb ramps are missing in the city.