We are using a different and superior timing system for 2019 (MYLAPS systems). Not a shoe tag transponder but a bibtag transponder on the back of the bib. 

This is a link of instructional video on how to wear a bib with bibtag transponder.

The BibTag is attached to the back of the runner’s BIB number and sends out a unique signal. Each tag sends out a unique UHF signal that enables the detection mats to identify the athlete and record the exact time at which the athlete passes the mat. The tags are designed to withstand rain and sweat as the mechanical part of the tag is covered by a foam spacer.