ES5, 97 95 81 bytes
ES5, 97 95 81 bytes
for(p=i=30;i--;)console.log(Array(p).join(" ",r=Math.random()*3|0,p+=r>1?-1:r)+0)
ES5, 112 98 bytes if function format is needed:
function a(){for(p=i=30;i--;)console.log(Array(p).join(" ",r=Math.random()*3|0,p+=r>1?-1:r)+0)}a()