Dual carriageways  A dual carriageway is a road which has a central reservation to  separate the carriageways.  Law RTRA sects 5 & 8  137. On a two-lane dual carriageway you should stay in the left-hand  lane. Use the right-hand lane for overtaking or turning right. After  overtaking, move back to the left-hand lane when it is safe to do  so.  138. On a three-lane dual carriageway, you may use the middle lane  or the right-hand lane to overtake but return to the middle and  then the left-hand lane when it is safe.  139. Climbing and crawler lanes.   These are provided on some hills.  Use this lane if you are driving a slow-moving vehicle or if there are  vehicles behind you wishing to overtake. Be aware of the signs and  road markings which indicate the lane is about to end.  140. Cycle lanes.   These are shown by road markings and signs.  You MUST NOT   drive or park in a cycle lane marked by a solid white  line during its times of operation. Do not drive or park in a cycle  lane marked by a broken white line unless it is unavoidable.  You MUST NOT   park in any cycle lane whilst waiting restrictions  apply.  highwaycodeuk.co.uk 73 