Newly constructed box-girder cantilever bridges with continuous spans, revealed extensive cracking in the webs after only two years of service. Continuous spans are complicated to design and secondary restraint moments due to creep, shrinkage and thermal effects develop at the connections. To explain the cause of cracking, the segmental construction sequence was analysed using non-linear finite element modelling, including the time-dependent effects of the evolution of the elastic modulus, shrinkage, creep and relaxation. The results showed that the webs cracked during the construction phase, due to tensioning of the tendons in the flanges. Seasonal temperature variations lead to further crack development.