Asphalt Pavement Design: Highway versus Railroad

The use of alphalt pavements as railroad trackbeds has received considerable attention in recent years. However, very little is known about the design of such pavements for railroad use. A comparison between highway and railroad pavements shows that, due to the difference in loading conditions, the stresses and strains in railroad pavements are quite different from those in highway pavements. To prevent fatigue crackings, the horizontal tensile strain at the bottom of asphalt layer can be used as a design criterion for both pavements. To minimize permanent deformation, the vertical compressive stress at the top of subgrade should be used for the design of railroad pavements, instead of the vertical compressive strain as is most frequently used for the design of highway pavements. The use of full depth asphalt concrete is not as effective in railroad pavements as in highway pavements.