“Reach back to a bygone era of quiet beauty ..”

The Three Arch Bridge

Once the Flowering Reflection Pond is drained, the base of the bridge will  need to be evaluated and a plan devised for reconstruction and restoration.  We don't know the actual work that will be needed until the footings and substructure can be visually examined.  The stonework that has fallen from the bridge will need to be retrieved, cleaned and evaluated. 

A little about the construction of an arch bridge ...

Stone, brick and other such materials are strong in compression and somewhat so in shear, but cannot resist much force in tension. As a result, masonry arch bridges are designed to be constantly under compression, so far as is possible. Each arch is constructed over a temporary falsework frame, known as a centering.  In the first compression arch bridges, a keystone in the middle of the bridge bore the weight of the rest of the bridge. The more weight that was put onto the bridge, the stronger its structure became. Masonry arch bridges use a quantity of fill material (typically compacted rubble) above the arch in order to increase this dead-weight on the bridge and prevent tension from occurring in the arch ring as loads move across the bridge. Other materials that were used to build this type of bridge were brick and unreinforced concrete. When masonry (cut stone) is used the angles of the faces are cut to minimize shear forces. Where random masonry (uncut and unprepared stones) is used they are mortared together and the mortar is allowed to set before the falsework is removed. Traditional masonry arches are generally durable, and somewhat resistant to settlement or undermining. However, relative to modern alternatives, such bridges are very heavy, requiring extensive foundations. 

Maudslay Bridge Maudslay Bridge

A view of the bridge from the pond's edge
showing the footings and one of the arches

Looking across the bridge down the Main Road.  Walls confine traffic to the center of the bridge surface.  The bridge fill of gravel provides a safe and durable surface

Where the arches are founded in a stream bed the water is diverted and the gravels excavated to a good footing. From this the foundation piers are raised to the base of the arches, a point known as the springing.  Falsework centering is fabricated, typically from timbers and boards. Since each arch of a multi-arch bridge will impose a thrust upon its neighbors, it is necessary either that all arches of the bridge be raised at the same time, or that very wide piers are used. The thrust from the end arches is taken into the earth by footings at the stream bed walls, or by large inclined planes forming ramps to the bridge, which may also be formed of arches. The several arches are constructed over the centering. Once the basic arch barrel is constructed, the arches are stabilized with infill masonry between the arches, which may be laid in horizontal running board course. These may form two walls, known as the spandrels, which are then infilled with loose material and rubble.  The road is laid and parapet walls protectively confine traffic to the bridge.

A view of the Flowering Pond The Pond with the Bridge in the background

 

PROJECT OBJECTIVE...

Updated 7/31/11

Before the Bridge can be restored, the Pond must be drained and dredged.  Stonework, both above and below the water line has fallen off and deteriorated.  We have begun the process of obtaining information about the construction of the bridge and the proper way to restore the structure.  The next step will be to obtain bids for the actual restoration work.  Go to our "Donate" page to make a pledge to support this endeavor.

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Bridge Construction

Built as a means to cross the Flowering Reflection Pond, the bridge carries the Main Carriage Road as it connects the Pasture Trail to the Castle Hill Trail.  Constructed of stonework, it carries a road bed of gravel.  An arch bridge is one of the strongest construction methods.  Arch bridges work by transferring the weight of the bridge and its loads partially into a horizontal thrust restrained by the abutments at either side of the arch.  The ancient Etruscans, Greeks and Romans used this method to construct bridges and viaducts, many of which are still in existence today.  Possibly the oldest existing arch bridge is the Mycenaean Arkadiko Bridge in Greece from about 1300 BC. The stone corbel arch bridge is still used by the local populace.

With a little thoughtful care, the three arch bridge has the potential to delight park users for generations to come. 

The Flowering Reflection Pond

You can't tell by looking at it now, but it originally had a white sand bottom and was home to koi fish and turtles.  A few turtles remain, but the white sands and koi are gone.  The pond is choked with weeds and fallen trees, a sad reflection of it's former glory.

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