A semicircular arched back heading 14 ft (4.3 m) wide and 17 ft (5.2 m) high is driven due north. Two joints are present; both strike due north. Set 1 dips 60◦ east; Set 2 dips 60◦ west. No other data are available. Yet, some support planning is required. Would conventional rock bolting be adequate in your estimation or would cable bolts, Dywidag, or Swellex bolts need to be considered? Explain your choice with the aid of sketches.