Bridges – Gangway – ramp – or dock leveler
Reexamination Certificate
2000-07-03
2002-09-17
Hartmann, Gary S. (Department: 3673)
Bridges
Gangway, ramp, or dock leveler
C014S073000, C404S018000, C404S019000
Reexamination Certificate
active
06449790
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a system for use as transit boarding platform structures. In particular the present invention provides panels to replace pre-cast concrete panels or cast-in-place concrete panels typically used for transit boarding platforms. In a preferred embodiment, the panels of the present invention are formed of reinforced polymer composite materials and incorporate a non-slip walking surface for improved wear and slip resistance.
2. Description of the Prior Art
Conventional concrete and wooden transit platforms have a durability problem due to degradation by environmental chemicals such as, salt, urea, acid rain, oils and greases as well as stray electrical currents. This necessitates regular maintenance and periodic replacement of the platforms at considerable cost to transit authorities. Steel and concrete are also susceptible to corrosive elements, such as water, salt water and agents present in the environment such as acid rain, road salts, chemicals, oxygen and the like. Environmental exposure of concrete structures leads to pitting and spalling in concrete and thereby results in severe cracking and a significant decrease in strength in the concrete structure. Steel is likewise susceptible to corrosion, such as rust, by chemical attack. The rusting of steel weakens the steel, transferring tensile load to the concrete, thereby cracking the structure. The rusting of steel in stand alone applications requires ongoing maintenance, and after a period of time corrosion can result in failure of the structure. The planned life of steel structures is likewise reduced by rust. Wood has been another long-time building material for bridges and other structures. Wood, like concrete and steel, is also susceptible to environmental attack, especially rot from weather and termites. In such environments, wood encounters a drastic reduction in strength which compromises the integrity of the structure. Moreover, wood undergoes accelerated deterioration in structures in marine environments.
Concrete structures are typically constructed with the concrete poured in situ as well as using some preformed components pre-cast into structural components such as supports and transported to the site of the construction. Constructing such concrete structures in situ requires hauling building materials and heavy equipment and pouring and casting the components on site. This process of construction involves a long construction time and is generally costly, time consuming, subject to delay due to weather and environmental conditions, and disruptive to existing traffic patterns when constructing a bridge on an existing roadway.
On the other hand, pre-cast concrete structural components are extremely heavy and bulky. Therefore, they are also typically costly and difficult to transport to the site of construction due in part to their bulkiness and heavy weight. Although construction time is shortened as compared to poured in situ, extensive time, with resulting delays, is still a factor. Construction with such pre-cast forms is particularly difficult, if not impossible, in areas with difficult access or where the working area is severely restricted due to adjoining tracks, buildings or platforms. There is a need for a light weight structure to facilitate installation in areas which have difficult access and working area. In addition a lightweight structure could eliminate the costly concrete foundations and steel support systems necessary to support conventional concrete platforms.
There have been solutions proposed for preventing deterioration of steel and concrete bridge and roadway decks. For example U.S. Pat. No. 5,901,396 discloses the use of an aluminum bridge deck to provide light weight and durability. In addressing the limitations of existing concrete, wood and steel structures, some fiber reinforced polymer composite materials have been explored for use in constructing parts of bridges including foot traffic bridges, piers, and decks and hulls of some small vessels. Fiber reinforced polymers have been investigated for incorporation into foot bridges and some other structural uses such as houses, catwalks, and skyscraper towers. These composite materials have been utilized in conjunction with, and as an alternative to, steel, wood or concrete due to their high strength, light weight and highly corrosion resistant properties. However, construction of load bearing applications built with polymer matrix composite materials have not been widely implemented due to extremely high costs of materials and uncertain performance, including doubts about long term durability and maintenance. As cost is significant in the construction industry, such materials have not been considered feasible alternatives for many load bearing traffic designs. For example, high performance composites made with relatively expensive carbon fibers have frequently been eliminated by cost considerations.
U.S. Pat. No. 5,794,402 is directed to a polymer matrix composite modular load bearing deck as a part of a modular structural section for a support structure described herein for exemplary purposes in the form of a highway bridge and deck therefore. The support structure of the present invention includes a plurality of support members and at least one modular section positioned on and supported by the support members. The modular section is preferably formed of a polymer matrix composite. The modular section includes at least one beam and a load bearing deck positioned above and supported by the beam. The load bearing deck of the modular section also includes at least one sandwich panel including an upper surface, a lower surface and a core. The core includes a plurality of substantially hollow, elongated core members positioned between the upper surface and the lower surface. Each of the elongated core members includes a pair of side walls. One of the side walls is disposed at an oblique angle to one of the upper and lower surfaces such that the side walls and the upper and lower surfaces, when viewed in cross-section, define a polygonal shape. Each core member has side walls positioned generally adjacent to a side wall of an adjacent core member. The polygonal shape of the core member preferably defines a trapezoidal cross-section formed of a polymer matrix composite material. The upper and lower surfaces are preferably an upper facesheet and lower facesheet formed of a polymer matrix composite material.
In public transit facilities, such as subway stations and railway stations, there is also a requirement for pedestrians to be able to safely navigate the platform. There is a need for pedestrians to get good traction on the platform to prevent slips and falls in particular on outdoor platforms that can be subject to wind, rain and snow conditions. In addition it is important for pedestrians to be able to detect the location of platform edges so that the pedestrian does not accidentally walk off the edge of the platform. The need for making platform edges detectable is of course particularly acute in attempting to make such facilities accessible and safe for blind or visually impaired persons.
In the 1980's a series of studies were undertaken in the United States to improve the design of buildings and transportation facilities to improve the mobility of the visually impaired. These studies culminated in recommendations on making potential hazards detectable to the visually impaired either by use of the long cane or underfoot.
Americans with Disabilities Act (ADA):
Accessibility Guidelines for Buildings and Facilities
set the requirements for the use of detectable warnings on inter alia transit platforms to warn visually impaired persons of hazards. The Guidelines require that detectable warnings shall consist of raised truncated domes of prescribed diameter, height and center to center spacing and shall contrast visually with adjoining surfaces. Detectable warnings used on interior surfaces are required to differ from adjoining surfaces in resiliency or soun
Astra Capital Incorporated
Hartmann Gary S.
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