Prefabricated Deck Installation for Railway Underpass Construction
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Solution Overview
Problem
The existing methods for creating a work of art by intersecting a lower track with an existing upper track require multiple temporary traffic interruptions, leading to increased duration and unavailability of the upper track, speed restrictions, and risks of incidents due to the use of auxiliary decks and special machines that can damage the upper track.
Innovation Solution
A method that involves removing the upper track, constructing supports on either side of the lower track, placing a prefabricated final deck, excavating underpinnings, and using sheet piles for support, allowing the upper track to be reinstated after the final deck is in place, thereby minimizing temporary traffic interruptions and reducing the risk of track damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple temporary decks are installed and removed during construction, then the upper track can support traffic between interruptions, but the number of temporary traffic interruptions increases and the total duration of unavailability increases
Solution Approach 1:
The final deck is installed in advance during the first traffic interruption, before the excavation work begins. This preliminary installation means the deck is already in place and can support traffic during the subsequent excavation phase, eliminating the need for a second deck installation and reducing the number of traffic interruptions from two to one.
Solution Approach 2:
The invention extracts and eliminates the auxiliary temporary deck from the construction process. By using only the final permanent deck that will remain after construction, the method removes the unnecessary step of installing and removing temporary decks, thereby reducing the number of traffic interruptions while maintaining track availability during work.
2Reliability
If auxiliary decks with reduced strength are used to support traffic, then traffic can resume on the upper lane, but speed restrictions and load limits must be imposed
Solution Approach 1:
The invention replaces the temporary auxiliary deck (a short-living object with reduced strength) with the final permanent deck that will remain in service indefinitely. This final deck is designed with full strength from the beginning, allowing unrestricted traffic flow without speed or load limitations, thereby eliminating the operational constraints associated with temporary decks.
3Ease of manufacture
If specialized machinery is used to drive a frame into an embankment, then the underpass can be excavated, but the upper track is at risk of significant damage and friction is very high
Solution Approach 1:
The invention extracts and removes the specialized frame-driving machinery from the construction process. Instead of using this equipment to push a frame into the embankment, the method relies on conventional excavation techniques after the final deck is installed, thereby eliminating the high friction, significant power requirements, and risk of track damage associated with the frame-driving operation.
Solution Approach 2:
The final deck serves as an intermediary structure that enables safe excavation without requiring the frame-driving machinery. By installing the deck first, it provides a stable platform and support system that allows subsequent excavation work to proceed using less aggressive, safer methods that do not pose a risk to the upper track.
Data Source
Figure 1
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Figure 3a
AI summary
The object of the invention relates to a method for constructing and installing an engineering structure for the crossing of an existing lower and upper track on two superimposed levels, comprising the following steps carried out in the final position of the engineering structure: - removing the upper track (1), - constructing supports (13) on either side of the location of said lower track, - positioning a final deck (6) on said supports (13), this deck being intended to support said upper track before and after the engineering structure has been constructed, - constructing an excavation (44) between the supports (13), under the final deck, said excavation being intended to be crossed by the lower track.