Particularly problematic was the fact that the highway passes in proximity to Pottle Lake, the water supply reservoir for North Sydney, which required installation of pollution control monitoring and containment systems.

In January 2008, a public meeting was held to discuss the required infrastructure to finally twin Highway 125 from its six lane divided portion in Sydney River to its eastern terminus at Grand Lake Road.

[3] The Cow Bay Road/Upper Prince Street overpass has now been cancelled, and a round-a-about is being proposed for Exit 9.

[citation needed] In 1970 the highway extended to Grand Lake Road bypassing Sydney to Nova Scotia Trunk 4.

In 2014 and 2015 the highway was twinned between Sydney River and Grand Lake Road (its eastern terminus).