The approach basins of navigation locks on still-water canals may be
symmetrical or asymmetrical in plan and are usually relatively short, since
no braking length is required, as vessels can reduce their speed before
entering the approach basin. The same applies to the downstream
approach basins of locks on waterways with flowing water, since the
vessels enter them against the flow direction.
However, downstream lock approaches have to be protected against
undesirable currents arising from spillway and/or power-plant discharges,
and from the lock emptying system.
When designing fender structures, dolphins, jetties, etc., it is neces-
sary to account for the forces (and displacements) which are likely to
occur owing to the impact of ships during mooring or collisions. The resul-
tant force will depend on the velocity of the ship and its angle with the
fender structure as well as, of course, on the ship displacement. Generally,
loaded push-tows have smaller velocities and angles of collision than
unloaded ones. The theoretical computation is fairly complicated, but
measurements in prototype indicate that the collision can be schematized
as a linear damped mass–spring system. The contribution of the dolphin
and ground to damping is considerable (Vrijer, 1983).
11.12 Inland ports
Inland ports serving the loading and unloading of vessels, transfer of
goods, and their further handling are connected with their hinterland by
water, highway and/or pipeline transport routes. The ports can have spe-
cialized zones or basins intended for the transfer of certain cargoes (ore,
coal, aggregates, sand, individual shipments, containers, etc. (Porteous,
1977)).
INLAND PORTS 491
Fig. 11.18 Lock with approaches on the Danube (after Cˇábelka and
Gabriel, 1985); dimensions in metres