The recent fire inside the Coastal Road tunnel raised questions about how safe Mumbai's growing network of tunnels really is. With several major underground transport projects now operational or nearing completion, mid-day looked at the emergency systems in place inside Metro Line 3 (Aqua Line), the Samruddhi Mahamarg's Igatpuri tunnel and the Mumbai-Pune Expressway Missing Link tunnels to understand what commuters should do during an emergency and how authorities are equipped to respond.