The Kingdom of Bhutan is a Himalayan country with most of its land above 2000 meters. Due to the mountainous terrain, road infrastructure plays a crucial role in the transportation of people and goods that directly contributes to the country’s socio-economic development, and the bridges on the national roads are of particular importance for ensuring road network continuity. Efficient and timely maintenance of the existing bridges is therefore necessary to prolong their service life as long as possible and ensure the service and safety for road users. To this end, it is necessary to understand the deterioration trends of these road bridges, but, until recently, such analyses were highly limited because there was insufficient data on the bridge conditions and their year of construction, which made it difficult to identify deterioration trends. However, the national road bridge inspection data that Bhutan now has includes construction year data for most bridges, as well as inspection results for each bridge by element and type of damage. This study aims to clarify the deterioration trends of the national road bridges in Bhutan by applying statistical analyses and modeling to the bridge database considering different deterioration factors. It is expected that the results of this study will help road infrastructure managers to realize more data-driven maintenance management.