Heron Road Workers Memorial Bridge

Ottawa Mayor Charlotte Whitton initially opposed the plans of Prime Minister John Diefenbaker to build the bridge to ease east–west traffic in the city.

In 1961, Diefenbaker's government threatened to reduce the amount of federal grants to Ottawa by the cost of the bridge if the city did not agree to build it.

[1] The original construction plan included two three-lane, 300-metre-long (980 ft) bridges, one eastbound and one westbound, and was budgeted at two and a half million dollars.

[2] The City of Ottawa awarded the contract to build the footings of the concrete piers supporting the bridge to Beaver Construction in February 1965.

[3] On August 10, 1966, a shift of about sixty to seventy workers were almost finished pouring 2,000 short tons (1,800 t) of concrete on the eastern side of the partially completed third span of the southern bridge when it collapsed at 3:27 p.m.

[3] It also triggered the nearby Dominion Observatory's seismometer, which prompted officials to issue a statement that the collapse had not been caused by an earthquake.

[2] Most of the injured were taken to the Civic Hospital, which was in the middle of switching from day to night shifts, allowing many medical staff to stay and deal with the influx of patients or to travel to the site to provide aid such as administering morphine to trapped workers.

Because many of the injured were recently arrived Europeans who were not fluent in English, were not carrying their identification at the time of the accident, and were covered in concrete, many blood transfusions were done without having a patient name, contrary to standard operating procedure.

[2][4] Among the dead were Leonard Baird, the project's resident engineer, and Clarence Beattie, the site foreman; the other seven workers who died were Jean Paul Guerin, Omer Lamadeleine, Edmund Newton, Lucien Regimbald, Dominic Romano, Raymond Tremblay, and Joao Viegas.

University of Toronto engineering department head Carson Morrison gave expert evidence using wooden models to show flaws in the unbraced falsework's design.

Secondary contributing factors included the use of green lumber, which was weaker than mature wood, differences between how the footings settled, and temporary overload of some of the posts.

John Bromley, the project engineer at Dillon in charge of approving the falsework design, testified that the fault for not recognizing the fatal lack of diagonal bracing was his alone and said that "My mind must have been a bit confused at the time.

Gaffney Ltd. was found guilty on two charges and fined $5,000, the maximum allowed penalty under the existing Construction Safety Act.

[10][3] From February 2011 to October 2012, Heron Road Bridge was closed because of a $15 million rehabilitation project — part of the city's Ottawa on the Move infrastructure plan — that improved its bearings, expansion joints, and pavement, among other changes.