Sorry, I couldn't find the traveling speed, but......
According to this mind boggling fact I found on Backyardnature;
One study showed that each year on an acre (0.4 hectare) of average cultivated land, 16,000 pounds (7200 kg) of soil pass through earthworm guts and are deposited atop the soil -- 30,000 pounds (13,500 kg) in really wormy soil!
The earthworm travels around 18 yards/hour. So in a day (12 hours) it would travel 216 yards (almost 200 metres), and in the 24 hours of a day and a night it would travel the distance of an Olympic running track. Hope this helps !!.