The bridge was designed by John Whitton, Engineer-in-Chief for the railways between 1856 and 1890, and is one of the only Whitton designed bridges remaining in use on the Main West Line. John Whitton has been described as the "Father of New South Wales Railways", responsible for the establishment of the basic framework of the NSW rail network. The bridge forms part of the larger historic Lithgow railway corridor, and exemplifies the style and technique used in construction of stone arch bridges, a form of construction which is relatively rare within the NSW rail network. Lithgow Underbridge was listed on the New South Wales State Heritage Register on 30 August 2013 having satisfied the following criteria. The place is important in demonstrating the course, or pattern, of cultural or natural history in New South Wales. The James St Underbridge has historical significance as the second oldest stone arch railway bridge in New South Wales still in use, and as one of the only original Whitton-era bridges still in use along the Main West Line. The place has a strong or special association with a person, or group of persons, of importance of cultural or natural history of New South Wales's history. The James St Underbridge has associative significance as it was designed by John Whitton, Engineer-in-Chief for Railways between 1856 and 1890. When Whitton was denied funds to continue with bridge construction using the expensive, imported wrought iron girder bridges, he chose to use stone arch viaducts for his major bridge works. The James Street bridge is a typical example. The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales. The James St Underbridge has aesthetic significance as it exemplifies the style and technique used in construction of stone arch bridges, in a form highly representative of railway construction. The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales. The stone construction of James St Underbridge is a comparatively rare technique within the NSW rail network. The place is important in demonstrating the principal characteristics of a class of cultural or natural places/environments in New South Wales. The James St Underbridge is representative of railway viaduct construction.