Complex sentence: The Spadina subway line, opened in 1978, runs down its median from Wilson to Eglinton, where it descends underground and follows the approximate route planned for later sections of the expressway, albeit underground.
Split into simpler sentences: The Spadina subway line, opened in 1978, runs down the median of the project right-of-way from Wilson to Eglinton. The route south of Eglinton follows the approximate route planned for later sections of the expressway, albeit underground.