Bridges are vital component of a country’s transportation system and its economy. However, large number of ageing bridges are either structurally or geometrically deficient in some way. In recent years, the remaining life of ageing bridges, were calculated by detailed evaluation and damage assessment using structural health monitoring (SHM) techniques integrating bridge-weigh-in-motion (BWIM) systems. The field study of an existing BWIM system in Winnipeg, Manitoba was conducted on the Prototype Bridge. This work was extended to analysis and comparison of the algorithms adopted on the Prototype Bridge which provided deep insight in identifying the sources of error in BWIM systems. It was followed by a study on fatigue assessment of steel girder bridges. This research contributes by incorporating field measurements from BWIM system on the Prototype Bridge to estimate fatigue loading and damage assessment. In analytical phase, a simply supported beam subjected to moving and pulsating load was investigated for signal simulation and filtering in MATLAB. This was done as an initial exercise to understand dynamic effects of the load and its relevance to bridge natural frequency. This work was presented in a conference proceeding, attached in appendix. The experimental part of this work aims to identify sources of error in BWIM systems with the aid of the Model Bridge and verify area method, tested on the Prototype Bridge. The method was further investigated on the Model Bridge to obtain 95% confidence interval over real bridge BWIM testing. Model bridge structure was fabricated using polycarbonate. The model was designed to have natural frequencies like the Prototype Bridge. It was instrumented at two different locations with piezoelectric sensors for estimating velocity, transverse position, and class of model truck. It was instrumented with electrical strain gauges at three transverse locations for estimating Gross Vehicle Weight (GVW) of model truck. Video camera was used for verifying velocity profile. Author endeavored to establish relevance of long-term monitoring data obtained from BWIM to bridge evaluation. In this work it was proposed that SHM will add another level of inspection to CHBDC clauses and will improve the estimation of load carrying capacities of existing bridges.