The near new Alice Springs to Darwin railway (1420km long) is again closed by washaways (floods). It uses conventional sleepers, but as it goes through uninhabited desert, it is hard to know where the water might flow and how big to make bridges and culverts.

How would Tubular track fare in similar circumstances?

The glowingly positive writeup about Tubular track is silent on this point. (Actually I would expect it to do quite well).

S. Ford 04 March 2010

How would Tubular track fare in similar circumstances?

The glowingly positive writeup about Tubular track is silent on this point. (Actually I would expect it to do quite well).

S. Ford 04 March 2010

“Because the rail stresses in TMT are so much lower, it is possible, when installing TMT, to use lighter rail sections, thus offering clients significant savings in rail procurement costs. In Tubular Track’s recent successful Namibian project, this benefit was highlighted when second hand 30kg/m rails were used for an 18.5 ton axle load application, providing the client with huge savings.”

This advantage occurs because TMT continuously supports the rail, unlike conventional transverse sleepers, where the rails are unsupported between sleepers, and therefore need to be stronger, heavier and more costly to compensate.

Put another way, conventional sleepers put too much strength into the transverse direction, and not enough strength into the longitudinal. This can only be overcome by installing more sleepers at closer spacings.

That clever engineer I. K. Brunel designed longitudinal sleepers for the Great Western Railway of England in the 1830s. They weren’t a total success as the vertical piles intended to hold the track down, ended up holding the track up as the earth underneath settled, causing an unexpectedly rough ride.

Brunel made his “Baulk” track out of wood because reinforced concrete used by TMT was not yet available. Similarly, TMT would have only been practical since say the 1950s.

Would TMT be useful for lowering floors in tunnels and under overbridges, and can it be used with that special LR55 rail?

S. Ford 05 Feb 2010

Tubular track ought to work with any gauge, so long as you don’t intent ever to change it, as might happen should certain grandiose plans for trans-African railways ever get built. Africa has too many places where, if railway of different gauges ever meet, an inconvenient break-of-gauge problem potentially occurs.

Can the gauge of Tubular be changed? On the one hand, the transverse ties are small and few in number so that they can be cut and reconnected, while on the other hand, the longitudinal bearers are heavy, continuous, and concreted into the ground, which may be very difficult to move.

Of course if one of the several albeit clumsy methods of overcoming a break of gauge is adopted, especially the latest and most elegant method, namely Variable Gauge Axles (VGA), then breaks-of-gauge cease to be a problem. (See another heading).

Three- or four-rail tubular track ought to be possible if allowed for at the time of first construction.

As a minimum, use of Tubular Track makes it ever more important to tackle the gauge question, since second chances may be lost forever. Where the choice of gauge is uncertain, conventional sleepers may well be a better choice.

S. Ford 02 Feb 2010.

Would Brunel be smiling in his grave?

SF 25 Dec 2009