The City of Ottawa has a plan to extend light rail to Barrhaven and finally separate Via Rail tracks from transit and traffic, but it pegs the cost at $3 billion and doesn't yet know where that money will come from.The design would also require tearing down 120 privately owned affordable rental units to make way for an elevated track between Algonquin College and the Nepean Sportsplex, something that concerns those residents and their Knoxdale-Merivale councillor.An environmental assessment headed to transportation committee on Nov. 2 lays out the route for 10 kilometres of twin tracks and seven stations south to Barrhaven. A study in 2018 already laid the groundwork for the other part of Stage 3: an 11-kilometre extension to Kanata and Stittsville estimated to cost $1.85 billion.Bridges over Via tracksMuch of the Barrhaven line would use existing Transitway, convert four existing transit stations, and would end at a future downtown Barrhaven.The plan also includes three new bridges over the Via Rail line at a cost of $400 million. That would eliminate the level crossings at Woodroffe Avenue, Fallowfield Road, and at the Southwest Transitway, the site of a tragic collision between a double-decker OC Transpo bus and Via train that killed six people in 2013."Safety upgrades at our Via crossings as part of this investment cannot be measured," wrote Barrhaven Coun. Jan Harder in her comments on the staff report.She called the environmental study for Stage 3 a "key piece" for taking LRT to fast-growing Barrhaven.It also includes a garage for eight double-vehicle trains at Highbury Park and Greenbank Road, at a site previously considered for future affordable housing.120 rental homes lostBut the first segment that could someday be built, from Baseline Station to Nepean Sportplex, involves building elevated tracks and three new stations at Tallwood, Knoxdale and the busy recreation centre.Staff say taking the train below ground level would be too risky, expensive and take longer to build.Not only would water and sewage lines need to be moved, but the water table is high in that location and construction carries the risk of settlement issues for up to 640 nearby houses and commercial buildings, staff say. But elevated tracks would require private property and affect 120 rental units. Advocates for the residents in Manor Village, which is now owned by Smart Living Properties, have been petitioning against losing affordable rental homes. "There's an extremely long runway before the shovels are going to hit the ground," said Coun. Keith Egli, who has been told any construction would be at least seven or eight years away.He knows that's no comfort to those now living with uncertainty, but says city staff are sympathetic and want to work with housing and private partners to give those residents places to move. "There's a will to find a way to come up with options and we have some time to do that," said Egli. He's also not entirely convinced the below-grade options in the Woodroffe corridor need to be off the table.Timelines and COVIDThe Baseline to Nepean Sportsplex section, along with the rail bridges, has been estimated to cost $2 billion, while the southern section to Barrhaven would cost another billion dollars.Ottawa officials have stated in the past their hope to have the provincial and federal governments each cover half the cost of Stage 3. For now, there's no promise of funding.And even if COVID-19 shifts travel patterns as people work from home, Egli said the Barrhaven line would still help thousands of people get to Centrepointe Theatre, Algonquin College and other places using methods other than their private vehicles."It's not all about going downtown, necessarily," said Egli, who pointed out councillors this week endorsed a strategy for dramatically cutting greenhouse gas emissions."LRT and the train … are an important part of making us a greener city overall."