(3.) The traction necessary upon it, though slightly greater than upon asphalte, is compensated for by the better foothold given to horses.
(4.) It is clean. If well constructed there should be no mud made upon it; all that appears upon its surface should arise either from its being imported upon it, or from the gravel with which it is sometimes necessary to dress the surface.
(5.) It presents a uniform and slight elasticity, which is of great benefit to vehicles passing over it.
(6.) It may be laid on a gradient of 1 in 20 with safety to the traffic.
The principal objections to wood as a paving are:—
(1.) It is said to absorb moisture and to smell offensively, but this has often been refuted.[81]
(2.) It is said to be difficult to cleanse without the aid of water, as dirt adheres to the wood, and lingers in the joints.
(3.) It is not easy to open it or repair it, for the purposes of gas and water pipes, etc., and rather a large surface has to be removed for this purpose, and it has to be left a little time after repairs before traffic is again allowed on it.
(4.) The wood swells if wet, and cases are on record of the side kerbs of streets being raised, and lamp posts thrown down, by the pressure of the wood thus swelling.[82]
With regard to the cost of wood paving. This must vary in different localities, according to the value of labour, of materials, and in the manner in which the work is done.