Precision Timing

While cycling along the Leigh Branch of the Leeds & Liverpool Canal recently to check my map data I encountered new signs, intended for cyclists.

This was the first sign I found, at Leigh.

Signpost at Leigh
Signpost at Leigh

I was intrigued by the precision of the timings shown on the signs, with Wigan shown as 59 minutes rather than 60 minutes, or 1 hour.  As it takes 10-15 minutes to cycle across Wigan this must be to a very precise location, but where?

Later I found this sign at Wigan, at the junction between the Leigh Branch and the main line of the Leeds & Liverpool Canal.

Signpost at Wigan
Signpost at Wigan

Leigh is 54 minutes and Wigan town centre is 6 minutes, a total of 60 minutes cycling, so where did the 59 minutes come from, was it to one end of the pier?