A bridge can add as much to a gardenas a waterfall. The pond needs to be designed so that it narrows at some point, preferably somewhere near the middle, and there the bridge can be spanned. If the pond is of much the same width throughout, a bridge may look out of place. Probably the easiest kind of bridge to make is a wooden one. Two strong beams are placed side by side to span the channel. They can be secured by burying in the soil or in concrete. Planks are then cut and screwed into the beams at right angles. The width of a bridge should be at least 60 cm. For convenience. A concrete bridge is almost as simple. Make a wooden ‘trough’ — which can be easily dismantled — and lay it across the channel. Fill with concrete and reinforcement. The sides and top surface can easily be faced with stones or paving slabs. The thickness of the bridge will depend upon its length and the weight it must carry.
An arched bridge requires a great deal more effort and skill. For this, one has to build an arched frame made of wood. Plywood bent over a series of formers is probably the simplest method of making such a frame. This must span the channel precisely and just come in contact with two concrete foundations set in the soil on either side. The foundations should be slightly lower than the soil so that they are not visible. The concrete for the arch will need to be made fairly firm, otherwise when you lay it on the wooden frame it will part in the middle and slump down on either side. The value of the foundations is that they will act as a buffer to the bridge as it sets. It would not be impossible, however, to construct the bridge without them. Simply dig out the soil on either side of the pond to receive the bridge and do the concreting in one job. Work is made much easier if the curve of the arch is not too great. It also means the bridge will be easier to walk over. A concrete arched bridge can be very effectively faced with bricks. One course of bricks is laid cross-wise over the top of the concrete form. Two further courses are arranged in ‘fan shape’ on either face of the bridge. (The inclusion of a larger key-stone adds a tremendous amount to the appearance of a bridge, if you can get one made.) Once the concrete part of the bridge is quite hard, you can face its top surface and then carry out the fan work as follows. Take off the side of the frame which was used to hold in the wet concrete. Move out the wooden frame on one side of the bridge to the width of one brick. The bricks can then be supported by the frame until the whole arch is completed, when it becomes self supporting. If a large keystone is being used, you may have to cut out a space in the wooden frame to accommodate its greater length. Having done one side, the frame can then be pushed through the bridge to appear on the other side, and the second set of bricks is cemented in place. To start this ‘fan work’ it is important to have two concrete foundations finished at such an angle that the fan of bricks can be started directly against them. A bridge of this kind does need a certain standard of craftsmanship. Any part of it which is not quite right will show up badly. But such a bridge offers great opportunities for individual touches of design and the results can be very satisfying.