I sent an email back to MoDot and requested more info about the type of signal and received this:
"There are cameras out there which have several zones about half the size of
a vehicle centered in the vehicle lanes. (They should be able to see the
cameras up on the signal mast arm). The front grill on a vehicle is what is
most noticeable to the camera. Cyclists can try turning to increase their
visible surface area, make themselves as "wide" as possible. It may help.
Found this webpage that talks about how to trigger green lights but it
mostly talks about loops. They might find it helpful.
http://www.wikihow.com/Trigger-Green-Traffic-Lights"
"Well-behaved women seldom make history." --Laurel Thatcher Ulrich
'09 Trek WSD 2.1 with a Brooks B-68 saddle
'11 Trek WSD Madone 5.2 with Brooks B-17