What do yellow and blue stripes on railway coaches mean ??

 These markings are a part of colour coded system that identifies different compartments.

Yellow stripes 

               A yellow stripe is   typically used to mark coaches reserved for differently abled passengers or medical staff.

Blue stripes 

             Blue stripes are often seen on reserved second class coaches.

White stripes 

              White stripes signals general compartment.

Green stripes 

                Green stripes marks ladies coaches.

Red stripes 

                 Red stripes highlights AC first class or executive class.