Here is teh Muni Code for your city. It refernces V.T.C.A., Transportation Code § 545.301 et seq, and 545.302 addresses this, which I have included below. I think you may be able to fight this one per the highlighted section in the VTCA as it refernces temporarily loading or unloading passengers in a no-parking area (see the highlighted section.) BUT, as always IANAL.
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ARTICLE IX. STOPPING, STANDING AND PARKING GENERALLY*
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*State law references: Stopping, standing and parking,
V.T.C.A., Transportation Code § 545.301 et seq.
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Muni Code
DIVISION 1. GENERALLY
Sec. 9-221. Obedience to signs.
A person commits an offense if, as the operator of a vehicle, he parks, stops or stands the vehicle in violation of an official sign, curb marking or street marking prohibiting, regulating or restricting the parking, stopping or standing of a vehicle.
(Ord. No. 259, § 1-68, 4-5-1968)
Also:
Sec. 9-228. Stopping, standing or parking prohibited in specified places.
No person shall stop, stand or park a vehicle except when necessary to avoid conflict with other traffic or in compliance with law or directions of a police officer or traffic control device in any of the following places:
(1) On a sidewalk;
(2) In front of a public or private driveway;
(3) Within an intersection;
(4) On a crosswalk;
(5) Within twenty (20) feet of a crosswalk at an intersection;
(6) Within fifteen (15) feet of a fire hydrant; or,
(7) Where signs are erected or curbs are painted indicating that such is not allowed.(Ord. No. 259, § 1-73, 4-5-1979; Ord. No. 999-9-90, § 2, 9-6-1990)
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V.T.C.A. Transportation Code
§ 545.301. STOPPING, STANDING, OR PARKING OUTSIDE A
BUSINESS OR RESIDENCE DISTRICT. (a) An operator may not stop,
park, or leave standing an attended or unattended vehicle on the
main traveled part of a highway outside a business or residence
district unless:
(1) stopping, parking, or leaving the vehicle off the
main traveled part of the highway is not practicable;
(2) a width of highway beside the vehicle is
unobstructed and open for the passage of other vehicles; and
(3) the vehicle is in clear view for at least 200 feet
in each direction on the highway.
(b) This section does not apply to an operator of a vehicle
that is disabled while on the paved or main traveled part of a
highway if it is impossible to avoid stopping and temporarily
leaving the vehicle on the highway.
Acts 1995, 74th Leg., ch. 165, § 1, eff. Sept. 1, 1995.
§ 545.302. STOPPING, STANDING, OR PARKING PROHIBITED IN
CERTAIN PLACES.
(a) An operator may not stop, stand, or park a
vehicle:
(1) on the roadway side of a vehicle stopped or parked
at the edge or curb of a street;
(2) on a sidewalk;
(3) in an intersection;
(4) on a crosswalk;
(5) between a safety zone and the adjacent curb or
within 30 feet of a place on the curb immediately opposite the ends
of a safety zone, unless the governing body of a municipality
designates a different length by signs or markings;
(6) alongside or opposite a street excavation or
obstruction if stopping, standing, or parking the vehicle would
obstruct traffic;
(7) on a bridge or other elevated structure on a
highway or in a highway tunnel;
(8) on a railroad track; or
(9) where an official sign prohibits stopping.
(b) An operator may not, except momentarily to pick up or
discharge a passenger, stand or park an occupied or unoccupied
vehicle:
(1) in front of a public or private driveway;
(2) within 15 feet of a fire hydrant;
(3) within 20 feet of a crosswalk at an intersection;
(4) within 30 feet on the approach to a flashing
signal, stop sign, yield sign, or traffic-control signal located at
the side of a roadway;
(5) within 20 feet of the driveway entrance to a fire
station and on the side of a street opposite the entrance to a fire
station within 75 feet of the entrance, if the entrance is properly
marked with a sign; or
(6) where an official sign prohibits standing.
(c) An operator may not, except temporarily to load or
unload merchandise or passengers, park an occupied or unoccupied
vehicle:
(1) within 50 feet of the nearest rail of a railroad
crossing; or
(2) where an official sign prohibits parking.
(d) A person may stop, stand, or park a bicycle on a sidewalk
if the bicycle does not impede the normal and reasonable movement of
pedestrian or other traffic on the sidewalk.
(e) A municipality may adopt an ordinance exempting a
private vehicle operated by an elevator constructor responding to
an elevator emergency from Subsections (a)(1), (a)(5), (a)(6),
(a)(9), (b), and (c).
(f) Subsections (a), (b), and (c) do not apply if the
avoidance of conflict with other traffic is necessary or if the
operator is complying with the law or the directions of a police
officer or official traffic-control device.
(g) If the governing body of a municipality determines that
it is necessary to improve the economic development of the
municipality's central business district and that it will not
adversely affect public safety, the governing body may adopt an
ordinance regulating the standing, stopping, or parking of a
vehicle at a place described by Subsection (a)(1), other than a road
or highway in the state highway system, in the central business
district of the municipality as defined in the ordinance. To the
extent of any conflict between the ordinance and Subsection (a)(1),
the ordinance controls.
Acts 1995, 74th Leg., ch. 165, § 1, eff. Sept. 1, 1995. Amended
by Acts 1999, 76th Leg., ch. 814, § 1, eff. June 18, 1999.