Super bad idea using railway ties!!!!>.. I have had friends do this and got really sick off the veggies they grew....use Non treated wood like fenceposts without any chemicals added to them....here is a link and they say to avoid wood with toxins!!Awesome! At the local park today, there was about 6 of these setup and I took some photos of them on how they were constructed. This weekend I'm planning on getting some railroad ties and making mine a little higher (3 foot). Biggest concern with the railroad ties is the arsenic embedded into them, but after careful reading I'm planning on putting some super duper plastic lining the sides of them and putting the veggies on the inside. And of course leaching out the run off for about 6-8 more months before planting. Love the fact that you used recycled pallets to do this.