This paper summarizes the results of laboratory tests in which authors investigated effects extremely high vertical load to a railway track segment. The segment consisted cut concrete sleeper (contact area: 290×390 mm) with pair direct-elastic rail fasteners; pieces had standard, full height; structure typical 350 mm depth ballast, underneath approx. 200 sandy gravel supplementary layer. whole ...

Elevated rail transit has been developed in some big cities in China in recent years. However, specialized codes for design of the bridges in the elevated rail transit system have not yet been established. Based on the prestressed concrete (PC) box girder bridges on Guangzhou metro line 4, some technical features of design principle and technology requisition, ensemble plan and design load of b...

The principal causes of cracking in prestressed concrete sleepers are the dynamic loads induced by track irregularities and imperfections in the wheel-rail contact and the in-phase and out-of-phase track resonances. The most affected points are the mid-span and rail-seat sections of the sleepers. Central and rail-seat crack detection require visual inspections, as legislation establishes, and i...

Abstract: Changes in the U.S. hours of service policy in January 2004 argue for an assessment of the safety implications of the new policy. Time-dependent logistic regression and case-control sampling are applied to derive a sample of 231 crashes and 462 non-crashes during 2004 for three national-scale trucking companies. The analysis focuses on changes in crash risk associated with driving up ...

Miles K (2011) Using attachment theory in mentoring. Nursing Times; 107: