A variable thickness fabric mat for use in railroad track structures, and particularly at stress transition zones in the railroad track; the mat is preferably formed of non-woven, multi-layered fabric, with the layers connected together, as for instance by needle punching to form an integral member. The mats are applicable for use with poor load bearing soils, and form a generally stepped, resilient bed for conventional railroad track structure, to help support and progressively spread the stress from the wheeled traffic, over a wider area. The mats provide for effective passing of runoff water, and aid in drainage of water from the soil beneath the mats, to thus improve the track support. The invention also provides a method of forming a railroad track construction so as to spread the stress from wheeled traffic at stress transition zones, over wider areas.