Synopsis
In November 2013, the installation of over 18,000 linear feet of Trex composite fencing for the light rail system in the Salt Lake City metropolitan area was completed. The project originated in a design study and product evaluation that began in 2007. Finding a cost-effective structure that would effectively serve as a sound barrier and security blockade for residential and commercial properties that backed to the rail lines was the intent of the original study. The Draper and Mid-Jordan LRT projects were the largest and most complex portions of the multi-year, multi-city initiative to link various municipalities in the Salt Lake City metropolitan area.
Project Scope
The combined lengths of the fence exceeded 18,000 linear feet. Total footage of material used was equivalent to over 24,000 of 6 ft. tall privacy fencing because much of the project included lines with heights up to 12 ft. Normally, these types of projects utilize masonry walls. However, the project engineers and the municipalities involved opted for privacy fencing to achieve four primary objectives: sound suppression, strength, aesthetics, and cost.
The project ran continuously through much of 2011 and 2012 with additional work performed in 2013. Most of the fence was installed in the City of Draper between 10200 S and Pioneer Crossing (12300 S). Part of the fence runs next to the Porter Rockwell Trail (Sandy Rail Trail) giving pedestrians and cyclists seclusion and protection from the trains.
The majority of the fence installation was for the Draper LTR TRAX line, a 3.8 mile extension of the UTA Sandy-Salt Lake line from its current terminus. The Draper Utah extension was built in the UTA-owned rail corridor, and features new stations at 11400 South, 11800 South, and Pioneer Road. Additionally, fencing was also installed at the 2700 W and 3200 W crossings in South Jordan, Utah.
The Draper and Mid-Jordan Light Rail Transit Design-Build projects were implemented by a Kiewit/Herzog/Parsons (KHP) joint venture. KHP engineered the sound walls to meet the requirements for noise reduction and durability.
Installation
From an installation standpoint, a significant consideration was the benefit of relatively light invasion from work equipment and crews needed to construct the fence. Whereas the construction of masonry walls would have required trenching for deep footers, much heavier equipment, and higher quantities of laborers, the fence only required 12″ wide footings every eight feet with depths no more than 66″. The holes were drilled with a mobile boring unit, and trucks drove along the fence line depositing concrete quickly and cleanly. Laborers and scaffolding were confined to the most immediate workspace each day for much of the project and materials were shuttled daily from a central yard just off the project site with pickup trucks and trailers.
Production was fairly rapid. Typically, 800-1,000 ft. of posts were set in a day by two to three crews. Crews worked in twos and each were able to build 150-200 ft. of fence daily. Towards the end of the project, the lines became active and required work stoppage every 20 minutes to clear the train route for safety reasons. While this affected productivity, it was also easy to manage because crews did not need to move heavy equipment out of the way during the stoppage.
For areas where the fence exceeded 8 ft. tall, 3/8″ square steel posts were sunk into the concrete and extended above ground. The hollow Trex posts have a 1/2″ thick wall which allows them to be self-supporting up to 8 ft. tall. Above that height, the Trex posts were used as sleeves over the steel posts.
Installation costs depend on height and typically run between $60-$150 per ft including materials.
Product Selection
After evaluating various products, Trex Seclusions composite fencing was selected. It was specifically approved to meet the criteria of the unique design requirements which specified fencing up to 12 ft. in height. The standard configuration for a Trex fence is 6 ft. and 8 ft. tall but project engineers successfully adapted the product to allow for the extra height requirements.
Utilizing a privacy fence for a barrier as an alternative to masonry presents an opportunity for the fencing industry in similar scenarios. Specific to the Trex fence profile, it fulfilled the need for full privacy with the strength to withstand the air pressure created by trains as they passed between the lines.
Trex is the country’s leading outdoor living manufacturer and the Seclusions fencing product is part of a large portfolio of outdoor living materials. Trex is made in the United States from reclaimed wood and plastic materials. The product is comprised of 95% recycled content.
The Trex Seclusions fencing design is unique in the composite fencing industry. Trex uses an interlocking picket system to inhibit noise transference, significantly reduce the requirement for fasteners, and create the same board-on-board look on both sides. The posts are self-supporting. Rails and pickets are assembled onsite and the fence panel is supported by a bottom rail.
The strength and durability of the Trex product was an important factor in selecting at for the project. Trex fencing has tested successfully for 130 mph sustained wind and 147 mph gusts (6′ tall), thereby ensuring that the fence would withstand the constant force of air pressure generated by the trains through the narrow corridors.
The project engineer specified heavy duty (3/8″ wall thickness) square steel posts for heights above 8 ft. The strength of the Trex fence post did not require more than a maximum 4 ft. extension of the steel post above the ground, thereby reducing the cost of steel for the 2,500+ posts installed. Using the fence’s aluminum bottom rail as mid-rails provided additional support when elevations exceeded 8 ft. in height.
The success of the fencing application for the UTA TRAX Light Rail Train project is a an indication of the benefits of using this unique product in an innovation fashion. Additionally, the aesthetics of the fence contributed to the adoption of the fence. Trex Seclusions fencing has the same look on both sides ensuring that both the residents on the private properties backing to the fence and the train passengers enjoy a softer, more natural barrier than a concrete wall.
For technical specifications and CAD drawings of the various elevations for Trex fencing, visit the Technical Center.
For more information on this project or on the product in general, please contact a representative.
