I would probably take defensive driving, although the "cop doesn't show up defense" often works. The particular statute involved and a blurb from a case interpreting that statute follow.
Texas Transportation Code § 542.404 "Fine for Offense in Construction or Maintenance Work Zone" states:
(a) If an offense under this subtitle, other than an offense under Chapter 548 or 552 or Section 545.412 or 545.413, is committed in a construction or maintenance work zone when workers are present and any written notice to appear issued for the offense states on its face that workers were present when the offense was committed:
(1) the minimum fine applicable to the offense is twice the minimum fine that would be applicable to the offense if it were committed outside a construction or maintenance work zone; and
(2) the maximum fine applicable to the offense is twice the maximum fine that would be applicable to the offense if it were committed outside a construction or maintenance work zone.
(b) In this section, "construction or maintenance work zone" has the meaning assigned by Section 472.022.
A blurb from a case on this section of the Transportation Code states: "Evidence was legally sufficient to support doubling of fine for speeding in construction zone with workers present, despite defendant's argument that no workers were in the particular section of the construction zone in which he traveled and his offer of photograph of zone as proof there were no workers present; fine enhancement statute did not require workers to be in a zone of potential danger or to be visible, citing officer and defendant testified defendant was exceeding posted speed limit and that he was driving through a posted construction zone when pulled over, officer testified workers were present, and defendant's photograph showed only one directional perspective of the zone." Chance v. State (App. 14 Dist. 2008) 2008 WL 4390637, petition for discretionary review refused, rehearing on petition for discretionary review denied.