Bryan-College Station Light Rail System Stations:
Reaping the Benefits of a Duplex System (Hot-Dip Galvanizing and Paint)
Prepared for:
The City Councils of Bryan and College Station
Prepared by:
Lisa Larsen, Ph.D. student, Civil Engineering-Emphasis in Transportation
Texas A&M University
Galvanize the Future: Edgard K. Schutz Scholarship Essay
March 30, 2013
Project Scope
The Bryan-College Station area is home to over 50,000 Fightin’ Texas Aggies and roughly
12,000 students who attend Blinn College. These campuses are subsequently two of the largest
special generators in the community. Recently completed and on-going improvements for
pedestrians on, and adjacent to, Texas A&M’s campus are bringing benefits to students.
Examples include the redesign of multiple intersections along University Dr. and the pedestrian
underpass that is under construction at the intersection of Wellborn Rd. and Old Main Dr. City
officials in both Bryan and College Station realize the vital part that the University and College
campuses play in the economic well-being of the community, and desire to supplement the
existing bus system that connects pedestrians to both campuses with a light rail system that
would facilitate the connectivity between Texas A&M, Blinn, the Easterwood Airport, student
housing, and local businesses. In November 2012, Bryan and College Station voters approved a
bond to make this light rails system a reality. This transit option will offer increased mobility
and accessibility for the residents of Bryan-College Station at large. Additionally, this system
will afford Texas A&M students a safe and reliable method of traveling from Main Campus to
West Campus—avoiding the traffic along Wellborn Rd. that is a reoccurring, hourly event, due
to the active railroad line that cuts through A&M’s campus. To avoid creating a conflict point
with the railroad tracks, the light rail system lines that cross Wellborn will run adjacent to the
pedestrian underpass known as Pickard Pass and the pedestrian underpass that is currently under
construction that was noted previously. This light rail transit design will also help mitigate
congestion problems that plague the campus during home football games at Kyle Field. It is
anticipated that the light right system will be built in six phases, as summarized below:
Phase 1:
Phase 2:
Phase 3:
Phase 4:
Phase 5:
Phase 6:
Texas A&M Campus
Connection between Texas A&M and Blinn
Connection between Texas A&M and Easterwood Airport
Expansion to student housing/businesses south of Texas A&M’s campus
Expansion to student housing/businesses north of Texas A&M’s campus
Expansion to student housing/businesses east of Texas A&M’s campus
The proposed alignments and station locations associated with Phase 1 (or that will ultimately
connect into Phase 1) are shown in Figure 1.
2
4
Considered
North
3
8
= Station
2
7
1
6
9
5
11
10
3
Figure 1: Proposed light rail alignment and station locations of Phase 1 (Google Maps).
Note that once all of the lines either on Texas A&M’s campus or that connect to A&M’s campus
are built, eleven stations will be needed. Here is a brief description of the function that each
segment of the light rail system related to the Texas A&M campus will serve:
Red Line: Connect the Administration Building to George Bush Library Museum.
Light Blue Line: Connect the southeast part of campus to George Bush Library
Museum.
Green Line: Connect student housing north of campus to the engineering section of
campus (eventually connects to Blinn).
Yellow Line: Connect student housing south of A&M to campus (with stations
connecting students to the Red Line and Light Blue Line that connect Main Campus to
West Campus).
Orange Line: Connect A&M campus to Easterwood Airport.
Purple Line: Connect into the Red Line and Purple Line and extend to student housing
and businesses east of campus.
Dark Blue Line: Connect to the Red Line and Green Line and extend east along
University Drive businesses.
Designing the Stations
In considering the design of the stations themselves, each station will be equipped with four
benches, one trash can, one recycling bin, and an awning to protect waiting passengers against
the harsh Texas sun. As was decided upon at a meeting held last week, all of these items will be
dark blue for branding purposes. As a transportation engineer interested in simultaneously
achieving a safe, cost-effective, and aesthetically pleasing design, I strongly suggest that you
utilize a duplex system—both hot-dip galvanizing and paint—rather than simply painting these
structures. This approach will be instrumental in achieving this three-fold mission of safety,
cost-effectiveness, and aesthetic appeal.
The following section provides some background information on the chemistry of a duplex
system, and how a duplex system works to protect steel from rust’s corrosive damage. This
background is followed by a brief explanation of how safety, cost-effectiveness, and aesthetic
appeal can be facilitated through use of a duplex system. This will be followed by a conclusion
that summarizes my recommendations for the station design aspect of this project.
Chemistry behind a Duplex System
In simple terms, hot-dip galvanizing is the process of covering steel structures with a layer of
zinc to help prevent rust corrosion. It is critical that the steel be clean before introducing the zinc
layer so that the proper metallurgic reaction can take place and enable the zinc to protect the
steel. Two types of corrosion protection are cited; namely barrier protection and cathodic
protection (American Galvanziers Association 2012). The galvanization process acts as both a
source of barrier protection (keeping electrolytes, such as water, away from the steel) and
cathodic protection (with zinc acting as an anode, enabling the steel to serve as the cathode, and
be protected from corrosion while the protective zinc layer is slowly worn away). Adding a
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layer of paint on top of the zinc layer puts another barrier protection in place and creates
additional time before maintenance is needed for a steel structure (American Galvanziers
Association 2012). Over time, a zinc patina layer can form when the zinc is exposed to the
atmosphere, which adds an additional layer of protection to the steel structure (American
Galvanziers Association 2012).
Safety
Failure of infrastructure caused by the compromise of the structural integrity of civil engineering
systems can lead to serious injury. Thus, taking the necessary precautions to prevent against
steel deterioration caused by corrosion is of utmost importance. The protection that a duplex
system offers provides multiple lines of defense against corrosion, with both the paint layer and
the galvanized steel layer protecting the steel from rust. Though it may not be considered at the
same magnitude as bridges, it is important to consider issues of safety for transit station
structures and ancillary items. Benches that deteriorate and rust may eventually fall apart, which
could injure the individual using the bench. Or, if the rusting gets too bad, waiting passengers
may be deterred from sitting on the bench as they wait for the light rail transit car to arrive. This
may lead to passengers standing too close to the light rail line and inadvertently falling on the
tracks or getting hit by an oncoming vehicle. Safety issues related to rusting of awnings pose
even more of a safety threat to waiting passengers. Structural failure of the awning could lead to
serious injury or death of passengers waiting under this structure (American Galvanizers
Association). Thus, from a safety standpoint, implementing a duplex system with not only the
protective layer of galvanized steel, but the paint layer as well may be a wise investment.
Cost-Effectiveness of a Duplex System
While generally associated with higher upfront costs ($3.68 per square foot for a duplex system
compared to $1.60 per square foot for just painting over steel (American Galvanziers Association
2012)), the “synergistic effect” created by having both a paint layer and a galvanized zinc layer
contributes towards delayed need for maintenance—which can ultimately lead to lower life-cycle
costs associated with a duplex system (American Galvanziers Association 2012). Stencel notes
that, “It is typical for a duplex system to provide corrosion protection 1.5 to 2.5 times longer than
the sum of the lifetimes of zinc and paint used individually (Stencel 2003, p. 26).” The cost of
implementing a duplex system compared against simply painting items, or galvanizing items
without adding a layer of paint, is shown in Table 1. The assumption is made that in the time it
takes for a duplex system to require being re-galvanized and re-painted (i.e., for a duplex system
to need to be redone), four tasks (two of just adding a paint layer and two of just adding a zinc
layer) would be necessary to achieve the same item lifespan when these two methods are not
used in tandem.
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Table 1: Total Number of Steel Items and Cost per Square Foot to Implement Treatments
Item
Number at
Each
Station
Number of
Stations
Total
Number of
Items
(1)
Estimated
Square Feet
per Item
Cost to
Implement
Duplex
System (2)
Cost to Just
Paint Over
Steel or to
Just
Galvanize
Steel
(3)
Steel Bench
4
11
44
30
$4,858
$2,112
Directly
Comparable
Difference
Between
Duplex
System and
Paint or
Galvanizing
[(3)*4 –(2)]
$634
Trash Can
1
11
11
54
$2,186
$950
$1,614
Recycling
1
11
11
54
$2,186
$950
$1,614
Bin
Awning
1
11
11
108
$4,372
$1,900
$3,228
*This is just considering the cost of purchasing items and applying treatments. It is assumed that periodic touch-ups will
be needed under both scenarios.
*It is also assumed that the lifetime of duplex system items is twice as long as the sum of lifetimes of zinc and paint used
individually (Stencel 2003).
*It was assumed that the cost per square foot to galvanize steel is roughly the same per square foot cost to paint steel
(Association 2013).
Thus, Bryan-College Station needs to look at the additional upfront cost of a duplex system as an
investment that will lead to fewer maintenance problems and a longer life-cycle of the station
structures than if steel structures were just painted or galvanized individually. In fact, the total
savings associated with this approach could lead to over $7,000 is maintenance savings.
Aesthetics
Aesthetics should be important for any city considering implementation of a transit system
because appearance is what will initially attract or dissuade riders from utilizing a transportation
system, and is partially a reflection of what the city values. Especially in the case of the items
found at the station, the City should want people to feel safe and have the setting be inviting.
One of the benefits of implementing a duplex system with a dark blue branded color scheme for
the items found at the light rail transit stops in College Station is that it will not only be
aesthetically pleasing and uniform, but will simultaneously provide an extra layer of protection
to the underlying galvanized steel (American Galvanizers Association). An additional benefit of
utilizing a duplex system is noted by Stencel, who states that, “Once paint has been weathered
down or damaged, the zinc is available to provide cathodic and barrier protection so rust will not
form, and paint will not peel (Stencel 2003).” Obviously not having the paint peel off of the
items located at the stations is desirable, and will contribute to the overall appeal at the station
locations.
Conclusions
Given the benefits of duplex systems to help protect steel structures, it is advisable that the cities
of Bryan-College Station look into this method as the light rail stations and the associated
ancillary items are planned for and implemented. Utilizing a duplex system will increase safety,
improve cost-effectiveness, and contribute to the aesthetic appeal at these stations.
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References
American Galvanizers Association. "Mass Transit: Hot-Dip Galvanzied Rail & Bus Stations." Retrieved
March 30, 2013, from http://gowithgalvanizing.com/mass-transit/commercial-rail/stations/StationBenefits/.
American Galvanziers Association (2012). "Duplex Systems." 1-11.
Association, A. G. (2013). "Frequently Asked Questions-How does the cost of hot-dip galvanizing
compare to other corrosion protection systems, such as paints?". Retrieved March 30, 2013, from
http://www.galvanizeit.org/about-hot-dip-galvanizing/what-is-hot-dip-galvanizing/faq#3.
Stencel, M. (2003). Double the Protection-Duplex coating systems enchance surface life and reduce
maintenance. Bridge Builder. Apr-Jun 2003: 26-28.
*Though the Bryan-College Station area and Texas A&M campus descriptions are based on real-life
settings, a light-rail system has not been approved by the City. This is example was selected to illustrate
the benefits of a duplex system and the station design is hypotheticall in nature.
*Not including the items on this References page or the title page, the word count of this essay is 1,877
words.
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