IN THE YARD THE IMPORTANCE OF THE RIGHT APPROACH SUPPORTED BY THE RIGHT EQUIPMENT:
HALMAR’S POST AVENUE BRIDGE REPLACEMENT PROJECT
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almar and its design partner McLaren Engineering Group was awarded the Long Island Rail Road Design-Build Post Avenue Bridge Replacement project in December 2016. The original approximately 100+ year old 2-track plate girder bridge was due for replacement primarily to allow for the greater width required for the additional mainline track, as a first preparatory step for the LIRR Third Track project. Additionally, the bridge was built at a time when the vertical clearance provided for truck traffic was significantly lower than today’s higher capacity vehicles. As a consequence, over the decades the bridge had been struck innumerable times by trucks traveling on Post Avenue passing under the bridge, on occasion more than once a day. The design-build contract required that the original bridge be removed and the new bridge installed and ready for operation over the course of one weekend service outage, which the LIRR scheduled for the weekend of October 21st and 22nd 2017, beginning Friday October 20th at midnight, and ending on Monday morning at 5am, a window of just 53 hours.
The Bay unit used on this project had 80 wheels on 20 axles, to support these very large and heavy loads.
With the design work well underway, Halmar mobilized and began work at the site in June of 2017. Site work and preliminary saw cuts of the east and west abutments were performed to accelerate the work that was to take place during the weekend outage. To facilitate the quickest possible removal and replacement of the bridge, Halmar opted to use a relatively new concept in accelerated bridge replacement projects, made possible by a piece of equipment called a Self-Propelled Modular Transporter (SPMT). The use of an SPMT for bridge replacement projects had only been utilized a few times previously in the U.S.
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The SPMT unit used on this project was provided by Bay Crane, and had to be ordered 6 months in advance to assure it availability. Boasting a lifting capacity of 1.2M pounds, the SPMT consists of an articulated arrangement of multi-axle platforms each of which can be individually pivoted 360 degrees and is computer operated via a walk along operator with a radio control system. The Bay unit used on this project had 80 wheels on 20 axles, to support these very large and heavy loads. The original bridge structure to be removed weighed in at roughly 700,000 pounds, while Halmar’s new wider structure weighed approximately 600,000 pounds. The replacement sequence began with the SPMT being maneuvered from the adjacent station parking lot, out onto the street while negotiating a 90 degree turn in very constrained space. The SPMT was aligned under the old bridge, lifted off its abutments, transported back to the parking lot, and set down on waiting temporary supports structures. Overnight the upper portion of the east and west abutments, which needed to be modified with new precast segments to achieve the higher elevation and accept the new wider bridge structure, were set in place. On the next day, the new bridge was lifted from its temporary supports in the parking lot and transported around the same sharp turn, down the street and into position, setting it gently and precisely down on the newly modified abutments 12 hours ahead of the bridge’s required start of service. Once the bridge was in place LIRR force account personnel installed the re-graded track and ballast. Thanks to this unique approach, the LIRR was able to re-open the tracks to service by 5am as planned.
week prior to the weekend outage. Halmar’s use of this approach on the Post Avenue Bridge Replacement project was a win-win for all concerned including the LIRR, the local community, the traveling public and for the Design-Build Team as well. The bridge was able to be built off site in a controlled environment, resulting in better accuracy of the structure compared with field erection, resulting in better alignment and fit in the field. The LIRR got a superior end product installed in one weekend outage, on-time and ready for their critical high volume
mainline service, the local community did not have to deal with the noise and interruption of typically long construction schedules, and the traveling public that depends on the railroad for their weekday commute, probably returned Monday morning without ever knowing what had taken place over the weekend. This project represented the first component of the much larger LIRR Third Track project which was awarded to the 3rd Track Constructors (a Dragados, Picone, Halmar JV) in January of 2018.
All the equipment was transported to the site on standard high flat/low boy trailers. No road or lane closures were required. Bay Crane assembled the units onsite in the station parking lot the
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