China
Africa
Explore chapters and articles related to this topic
Ro-Ro ships and dedicated short sea shipping terminals
Published in Tiago A. Santos, C. Guedes Soares, Short Sea Shipping in the Age of Sustainable Development and Information Technology, 2020
Manuel Ventura, Tiago A. Santos, C. Guedes Soares
In general, platforms are mounted on wheels and can be towed by tractor units. If they have a height of 1.2–1.4 m above the ground, they correspond to trailers or semi-trailers prepared to circulate in roads. There are also low cargo platforms, called roll trailers, with a height above the ground of about 0.6 m and wheels at the rear end, which cannot circulate outside the terminal. These are used for over-dimensioned cargos or containers and generally can take more weight than the standard platforms. Their length is generally enough to fit a 20 ft or a 40 ft container. Roll trailers are towed by terminal tractor units using an intermediate piece of equipment called gooseneck to lift the forward end of the roll trailer. The set of the tractor unit, gooseneck and roll trailer is often called a ‘mafi roll trailer system’. Shipping companies generally operate fleets of roll trailers for the use of their customers. Another type of platform, which is wheelless, is called a cassette. These are handled using special terminal tractors called lift-trailers (or translifters). They may also take containers and generally have a length of 40 ft. Both these types of cargo units, roll trailers and cassettes, can be tightly stowed side by side inside the ship and, therefore, need less space on the cargo deck than do trucks or trailers. They may also carry heavier cargos than trucks, but the strength of the Ro-Ro decks must be taken in consideration, as well as the slope of the ramps and the pulling power of the terminal tractor, as these parameters may limit, in practice, the permissible load in these units. Table 2.2 shows a summary of the main characteristics of these intermodal units.
Correlation of dynamic cone penetrometer index to proof roller test to assess subgrade soils stabilization criterion
Published in International Journal of Geotechnical Engineering, 2018
S. Hamed Mousavi, Mohammed A. Gabr, Roy H. Borden
The proof roller test has been carried out as a technique for subgrade quality assessment in road construction for decades. A proof roller is a loaded single-axle, four-wheel trailer, that is used for compacting the roadbed and testing its stability and uniformity of compaction. Based on the North Carolina Department of Transportation (NCDOT) specifications (NCDOT 2006, Section 260), the maximum centre-to-centre spacing between adjacent wheels is 813 mm, with tire pressure between 470 and 500 kPa. The load capacity of the trailer is from 427 to 445 kN. A proof roll trailer is pulled over the subgrade soil, and the observed pumping and permanent deformation are used as the basis for the subgrade’s pass/fail criteria. Generated pumping under proof roll loading is associated with the stiffness properties of the deep soft layers, while rutting is related to plastic deformation within shallow layers. The acceptable rutting depths vary between 0 and 80 mm, across the US, based on the proof roll trailer specification and state criteria, Hambleton and Drescher (2008). Based on the NCDOT specifications, an induced surface deformation by proof roll testing that is less than 25 mm is considered as acceptable.