Mayor Jim Watson says Rideau Transit Group has achieved substantial completion on Ottawa's LRT project.

Watson made the announcement on Twitter Saturday afternoon.

The milestone clears the way for a 12-day trial run of the system to begin this week. It's the next key milestone before RTG hands the keys to the system over to the city.

It's the second time RTG has applied for "substantial completion" status. On their first attempt in mid-May, the city disagreed and an independent certifier sided with the city.

After the 12 days of testing is complete, the city would take over the system for a month before it opens to the public, meaning passengers could be riding the rails in September.