Construction of Railway and Light Rail Embankments Using Geofoam Blocks

As in highway embankment construction, geofoam blocks can also be used for railway embankments constructed over soils with low bearing capacity (Figure 1). Although geofoam block technology has been a proven and mature geotechnology for highway embankment construction since 1972, there are relatively few studies on its use in railway embankments (Li, 2014; Neupane, 2015).

Geofoam block railway embankment
Figure 1. Geofoam block railway embankment

Geofoam block technology has been used in commuter rail alignments (Figure 2) and light rail embankments (Figure 3) in the state of Utah, USA (Snow et al., 2010; Li, 2014; Neupane, 2015). Instrumentation and monitoring carried out along the commuter rail alignment showed that the geofoam block embankment experienced approximately one-quarter of the deformation measured in a conventional soil embankment during train passage (Neupane, 2015). Overall, the average deformations measured in geofoam block embankments constructed for both commuter rail and light rail systems were found to be significantly smaller than those measured in conventional soil embankments (Neupane, 2015).

UTA FrontRunner geofoam block railway embankment
Figure 2. Geofoam block railway embankment: UTA FrontRunner (Salt Lake City, Utah, USA) (Li, 2014)
West Valley UTA TRAX geofoam block light rail bridge approach embankment
Figure 3. Geofoam block light rail bridge approach embankment – West Valley UTA TRAX: (a) Typical cross-section, (b) precast panel detail at the vertical section, (c) connection of the reinforced concrete column and foundation supporting the catenary system to the load distribution platform, (d) completed reinforced concrete column and foundation for the catenary system together with the load distribution platform, and (e) construction of the geofoam block light rail bridge approach embankment (Salt Lake City, Utah, USA) (Snow et al., 2010) (Source: S. F. Bartlett)

In addition to these applications in the United States, details of the first railway embankment constructed using geofoam blocks in the United Kingdom were published by O’Brian (2001). The project involved removal of an existing railway bridge and its replacement with a railway embankment constructed using geofoam blocks. Geofoam block placement continued until the fill reached the elevation of the underside of the existing bridge girders, without interrupting railway traffic during this stage (Figure 4a). After completion of the geofoam block embankment, railway traffic was temporarily suspended, the deteriorated bridge girders were removed (Figure 4b), the railway track structure was constructed over the geofoam block fill (Figure 4c), and the railway was reopened to traffic.

Geofoam block railway embankment in Manchester, United Kingdom
Figure 4. Geofoam block railway embankment: (a) Placement of geofoam blocks while railway traffic remained in operation, (b) suspension of traffic and removal of the deteriorated railway bridge girders, and (c) typical cross-section (Manchester, England, United Kingdom) (O’Brian, 2001).

REFERENCES

  • Li S (2014) Evaluation and numerical modeling of deflections and vertical displacement of rail systems supported by EPS geofoam embankments. M.Sci. Thesis, The University of Utah, SLC, UT
  • Neupane, R. (2015) Expanded polystyrene geofoam embankment for support of railways and bridges. Ph.D. Dissertation, The University of Utah, SLC, UT
  • Snow R, Webb J, Sander M (2010) Light rail on geofoam West Valley UTA trax project. 2010 AREMA Conference and Exposition, Orlando, Florida, USA