Dominion Atlantic Railway
Bear River Bridge

Digby County, Nova Scotia

Dominion Atlantic Railway: Bear River Bridge swing span mechanism, Digby County, Nova Scotia, 13 Dec 2011

Dominion Atlantic Railway    Bear River Bridge    13 December 2011

A close view of the swing span mechanism, taken at high tide.

How did the swing span work?

Dominion Atlantic Railway: Bear River Bridge swing span mechanism, Digby County, Nova Scotia, 13 Dec 2011

Dominion Atlantic Railway    Bear River Bridge    13 December 2011

A close view of the machinery that turned the swing span.

Dominion Atlantic Railway: Bear River Bridge, Digby County, Nova Scotia, 22 Nov 2011

Dominion Atlantic Railway    Bear River Bridge
22 November 2011   10:36am

A close view of the rotary shaft that operated the locking mechanism
at the east end of the swing span.


How did the swing span work?

From time to time, the swing span was opened to allow a ship to pass on its way upriver or downriver.  The swing span's normal position was "closed" – that is, positioned so that the railway track was continuous all the way across the bridge, to enable train movements as needed in the daily operation of the railway.  When a ship arrived, wanting to pass through the bridge, someone had to go out on the bridge to the swing span, to operate the machinery.  The first step was to release the locking mechanism that normally held the span in place with the railway track properly aligned – the photograph next above shows a rotary shaft that worked this locking mechanism at the east end of the swing span.  Once the locking mechanism was released, the machinery that turned the span sideways could be used.  The operation of this swing span was always done manually – there was never any steam engine or electric motor to do the work.  The railway company employed a person, the bridge tender, who lived close by, to be available at any time as required to open the swing span for a ship and then close it after the ship had passed through.  Closing the swing span was done in two stages: first the span had to be turned to its normal position, then the locking mechanism had to be engaged.  The locking mechanism was vitally important.  The railway track on the swing span had to be brought into proper working alignment with the matching track on the fixed spans at both ends.  A safe alignment was within five millimetres, vertically and horizontally, for each rail at both ends of the swing span.  The locking mechanism had to hold these rails reliably and securely in safe alignment, vertically and horizontally, as heavy train wheels rolled over the rail joints imposing the usual lateral and vertical impact forces.  A special challenge for the locking mechanism was to prevent far end lifting when a train first entered the near end.  When the swing span was closed and locked in place, it was the duty of the bridge tender to visually inspect the alignment of the rails at both ends of the span, before he/she gave the signal to a waiting train crew to proceed.

A modern job description of
the duties of a Bridge Tender

The bridge tender operates machinery to open and close the swing span to allow passage of marine traffic.  The bridge tender must be capable of working alone in a safety sensitive position.  Safety is always the most important task of the day.  The bridge tender will do his/her best to make sure that trains safely pass over the bridge, and watercraft safely pass through the draw, without delay or incident.  The bridge tender's responsibility is to make sure that the bridge is clear of trains prior to opening the bridge.  When maintenance or lubrication is being performed on the bridge, the bridge tender must assure that there are no maintenance personnel on or under the bridge prior to opening the bridge.  The bridge tender must observe the vessels as they navigate through the channel, making sure that they are clear of the structure before closing the bridge.  The bridge fendering and dolphins should be checked each day for damage.  The bridge tender receives and answers navigation signals from approaching small marine vessels; identifies type and size of vessels to estimate proper time to stop trains and open span; activates railway signals to stop oncoming trains on the bridge.  Opens and closes span according to applicable standard or emergency procedures and in accordance with government regulations.  Inspects, tests, and performs maintenance to equipment on a periodic basis to ensure that mechanisms operate properly.  Performs routine maintenance activities such as cleaning, oiling, and greasing gears, locks and wedges.  An above-deck cursory inspection should include the track alignment.  Bridge rail joints, where mating sections of track separate to allow the bridge to open, must be checked for improper metal deformation conditions at the joint; chipped rail; loose or deficient bolts, spikes or anchors; poor joint alignment; excessive movement; deficient conditions of ties and other abnormalities.  Makes entries to daily logs to record all bridge openings; this log will include the date and time the bridge was opened and the time the bridge was closed; also, the log will identify the type of vessel passing through the draw and the name of the vessel.  Reports all incidents to appropriate railway personnel and completes required incident reports.

Reference:— Bridge Span Operator (an official job description, 1992)

Reference:— The Bridge Tender (an AREMA discussion paper, 2001)
American Railway Engineering and Maintenance-of-Way Association

Retired bridge tender

Dec. 21, 1972 — The unique $3.5 million Bear River (highway) bridge opened to traffic, replacing the one-lane Victoria Bridge built 72 years earlier when vehicles got along with one or two horsepower.  Construction of the bridge began April 30, 1971, precisely at 11am when dynamite blasted rock on the west side of the river.  Watching as the construction unfolded was Fletcher Adams, 90, of Smiths Cove, and he was among the first to cross the new span.  Adams spent 34 years as the bridge tender on the adjacent railway bridge, which he had helped construct...
Source:— 35 Years Ago: New bridge opens across Bear River in the Digby Courier 19 December 2007

Go To:   Photographs of the Bear River bridge

Go To:   Photographs of the Sissiboo River bridge

Go To:   History of Railway Companies in Nova Scotia

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First uploaded to the WWW:   2011 December 14
Latest update:   2012 February 07