When you arrive at Petra, a local Bedouin will offer you a ride in his horse-drawn buggy through a valley called Bab as-Siq and then through the Siq passage to the start of the ancient city. If you decline, then several other drivers will try to convince you. It is something to consider. The walk is not far or strenuous. But this is inexpensive fun and you will reach your destination faster. Besides, you will do plenty of walking while exploring the archeological site.