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Track ballast should never be laid down less than 150 mm (6 inches) thick, [5] and high-speed railway lines may require ballast up to 0.5 metres (20 inches) thick. [6] An insufficient depth of ballast causes overloading of the underlying soil , and in unfavourable conditions, overloading the soil causes the track to sink, usually unevenly. [ 7 ]
Steel ties are lighter in weight than concrete and able to stack in compact bundles unlike timber. Steel ties can be installed onto the existing ballast, unlike concrete ties which require a full depth of new ballast. Steel ties are 100% recyclable and require up to 60% less ballast than concrete ties and up to 45% less than wood ties.
A ship's draft/draught is the "depth of the vessel below the waterline measured vertically to the lowest part of the hull, propellers, or other reference point". [1] That is, the draft or draught is the maximum depth of any part of the vessel, including appendages such as rudders, propellers and drop keels if deployed.
Schematic cross section of a pressurized caisson. In geotechnical engineering, a caisson (/ ˈ k eɪ s ən,-s ɒ n /; borrowed from French caisson 'box', from Italian cassone 'large box', an augmentative of cassa) is a watertight retaining structure [1] used, for example, to work on the foundations of a bridge pier, for the construction of a concrete dam, [2] or for the repair of ships.
Ballast weight is also added to a race car to alter its performance. In most racing series, cars have a minimum allowable weight. Often, the actual weight of the car is lower, so ballast is used to bring it up to the minimum. The advantage is that the ballast can be positioned to affect the car's handling by changing its load distribution.
[1] [2] [3] It is the sum of the weights of cargo, fuel, fresh water, ballast water, provisions, passengers, and crew. [1] Draft or draught (d) or (T) – The vertical distance from the bottom of the keel to the waterline. Used mainly to determine the minimum water depth for safe passage of a vessel and to calculate the vessel's displacement ...
The classical, archetypal definition of ballast is a low, central weight to optimise centre of mass, reduce turning moment and therefore resistance to the boat keeling over, however tends to be higher in self-righting vessels.
[4] [5] [1] [6] Master mariners should ensure there is sufficient minimum UKC for their ships; ports should ensure sufficient minimum UKC for the type and draft of ships due to arrive in the port. [ 7 ] [ 3 ] Ships typically calculate their UKC to meet criteria for ports to minimise the risk of maritime incidents. [ 3 ]