Fatigue life assessment of TTC streetcar concrete pavements

The Toronto Transit Commission, TTC traditional embedded track for mechanically jointed rails, is performing satisfactory except for accelerated surface concrete deterioration. By far the most damaging group of deterioration processes in streetcars concrete pavement is due to wheel impact on the joints which will subsequently excite a response on the track. The enhancement of special trackwork, STW service life was the initiative to explore encapsulation technology advances in embedded track materials and construction methods. This aimed to extend the life cycle of the track from current average of 15 years towards target life of 50 years. In the present study, attempts at finding and patterning the localized cracks, especially wheel impact fatigue cracks, are carried out. This issue was investigated during the course of an experimental program demonstrated by simulating the wheel impact loading in concrete under repeated load application. Specially designed specimens were used to represent sheet rubber and urethane encapsulation system proposal against the current assembly. This research reviews the pros and cons of various factors influencing the life cycle of the current assembly and examining and assessing between alternative track construction methods and materials at the joints and examining the concrete's performance both during the impact fatigue loading resulting in inclined cracking and ongoing service life and durability issues under combined environmental and mechanical loadings. Experimental results show that it is possible to achieve the targeted service life of 50 years, based on minimum of 10 time superior performance for either of the proposed encapsulation technologies vs. current construction methods.