The Gunningsville Bridge—The Fourth Petitcodiac River Bridge

The Petitcodiac River runs adjacent to the City of Moncton and constitutes a natural barrier between the counties of Westmorland and Albert. The necessity of bridging this river was apparent from the very beginning of the settlement. The Petitcodiac River has the reputation of having the highest tidal variation in the world. Along with the fast current and unstable silty slopes, the river crossing was a very dangerous venture for the early settlers. The requirement for a permanent bridge was quickly accepted as a necessity but its construction proved to be a difficult and dangerous undertaking. After multiple attempts and failures due to piers being swept away by storm surges, it was decided that to stabilize the piers, they had to be anchored to the bedrock in the river. This proved to be one of the most challenging engineering endeavours of the project. The excavation of the pier footings to bedrock was to be done in the dry to permit the concrete to be placed and properly cured. The silty nature of the river bed and banks made the standard methods of retaining the river flow and the silt infiltration inadequate. To permit excavation to bedrock and to create a dry workspace, it was decided to utilize pressurized caissons which were floated in place. A specialized workforce known as “sandhogs” had to be recruited from New York City to work under these dangerous pressurized conditions. This paper details the work that was carried out to construct this vital link between the communities which served this purpose from 1917 until its replacement in 2005.