509 Harbourfront is a Toronto streetcar route in Ontario, Canada, operated by the Toronto Transit Commission and connecting Union Station with Exhibition Loop. History 1990–2012 The 509 Harbourfront began service in 1990 as the "604 Harbourfront" and was referred to as the "Harbourfront LRT". It was the first new Toronto streetcar route in many years, and the first to employ a dedicated tunnel, approximately long. The route starts with an underground loop at Union station, runs south along Bay Street to the underground Queens Quay station, then turns west and emerges onto Queens Quay. The line's original terminus was Queens Quay and Spadina Loop, at the foot of Spadina Avenue; beyond this point non-revenue track ran north on Spadina to King, to connect the new line with the rest of the network. Numbers in the 600-series were used at that time within the TTC for rapid transit routes (i.e., subways and the Scarborough RT) rather than single-digit numbers as is the case today, and the Harbourfront LRT was given the number 604 to indicate that it was different from other streetcar routes. The 1990 TTC Ride Guide indicated the route with its own colour like a subway line rather than as a streetcar route. Since the route is not grade-separated, this was later felt to be misleading and it was subsequently treated like other streetcar lines, taking the number 510. In 1997, the completion of a dedicated right-of-way on Spadina Avenue resulted in the Harbourfront route being relaunched as the 510 Spadina. The "Harbourfront" route name disappeared until 2000, when the Queens Quay streetcar tracks were extended west to Bathurst and Fleet Streets. The Harbourfront name was then combined with the new number 509, and extended to Exhibition Loop at Exhibition Place, sharing its route with the 510 from Union to Spadina and with the 511 Bathurst from Bathurst onwards. Between September 2007 and March 2008, the Fleet Street portion of Route 509 was converted to a parallel private right-of-way, so that the entire route operates entirely separate from road traffic. 2012–present In July 2012 Waterfront Toronto began a major reconstruction of Queens Quay West, requiring the 509 streetcar to be replaced with buses for the duration of the construction. On 12 October 2014, streetcar service resumed on 509 Harbourfront route after an absence of over two years in order to rebuild the street to a new design, and to