[1] John Whitton chose to use stone arch construction when denied sufficient funds to use imported wrought iron girders.

[1] As at 19 October 2009, the bridge is in moderate condition with the following defects: several cracks and erosion in the stone arches, and parapets out-of-line with missing mortar.

[1] As at 9 October 2009, the James St Underbridge is significant as the second oldest stone arch railway bridge in New South Wales still in use.

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.

[1] Lithgow Underbridge was listed on the New South Wales State Heritage Register on 30 August 2013 having satisfied the following criteria.

[1] The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales.

[1] 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.