A bridge must be inspected on regular basis to ensure public safety and to protect publicrninvestment. Bridge inspection program helps to identify the needs of bridges for repair,rnmaintenance, preservation, reconstruction and replacement. Many bridges haverncollapsed in Ethiopia and other countries. Periodic inspection and maintenance ofrnbridges helps to avoid this problem.rnRecently bridge inventory and inspection program has begun in Ethiopia. This programrnhas proved to be very useful in providing information about bridges in Ethiopia whichrnotherwise would have been unavailable. According to a report from this program, quite arnlarge number of bridges are in critical condition needing immediate intervention. Thisrncan be disastrous if remedial actions are not taken by the concerned bodies in due times.rnOne of the key components of a bridge inspection is load rating. This is a method tornknow the strength of an existing bridge to carry current traffic loads. When the loadrnrating of a bridge is greater than or equal to one, it implies that the bridge is strongrnenough for current traffic conditions. Load rating or strength evaluation of existingrnbridges is quite different in some respect from designing of a new bridge. This is becausernin strength evaluation, the loads are taken to represent the actual traffic condition.rnSince bridge inspection and maintenance activities started recently in Ethiopia, much isrnnot known about strength evaluation of bridges. This thesis has thus made an attempt tornaddress such problem by developing a computer program that will be used to load andrnevaluate the rates of simple span slab type and girder concrete bridges