Proposed Advanced Technology Class 5AT 4-6-0 Steam Locomotive

Outline drawing of the 5AT locomotive as prepared by David Wardale in January 2005 after completion of the FDCs, incorporating visual changes resulting from the outputs of those calculations. [See "The Locomotive" page for a before-and-after comparison.]

Note: to make it easier for regular visitors to keep track of changes to this site, a list of 'updates' is provided on the Updates page.


The 5AT is a totally new steam locomotive design, incorporating the latest proven steam locomotive technology, for hauling main line steam charter and railcruise trains. With a 70% increase in thermal efficiency over "classic" steam, and almost 3500 horsepower available at the cylinders (more than a "Deltic"), its perfomance will amply demonstrate what could have been achieved had steam locomotive development been fully exploited in the 20th Century.

A brief summary of the project, as prepared by Alan Fozard for the "Modern Steam" conference held in York on 11th Dec 2006, is appended.

Major features include:

The 5AT's fuel and water ranges are calculated to be 925 km/570 miles and 610 km/380 miles respectively under representative average service conditions; and 552 km/345 miles and 367 km/230 miles respectively at a maximum operating speed and power (i.e. at 113 kph/70 mph with 1890 kW/2535 hp at the drawbar.) See FDC 1.3 items 143 to 152.

This diagram (which first appeared in Wardale's Steam Railway Article of June 2002) provides a dramatic comparison between the power-weight ratio of modern diesel and electric traction (blue lines) and the 5AT locomotive (red lines) when hauling a range of train sizes. A train's power-weight ratio determines the rate of acceleration that it can achieve. An indication of the potential performance that this represents can be seen from the following output from the appended computer simulation of the 5AT hauling a 375 tonne train from Crewe to Carlisle as provided to us by Dr David Pawson. More detailed performance simulations by David Pawson can be found on the Performance Predictions page of this website.

This painting of the 5AT by Robin Barnes illustrates the final outline of the locomotive as defined by the completed Fundemental Design Calculations. A brief description of the visual changes in the locomotive that are illustrated in this painting is given on the Artist's impressions page which now includes captions by Robin Barnes describing each of his paintings.
[Click on the image for an enlarged version. More of Robin's beautiful paintings can be viewed by clicking on the thumbnails below]

Page last updated 26th Apr 2007 - Robin Barnes' latest paintings added
Page last updated 11th Feb 2007 - Robin Barnes' latest paintings added
Page updated 18th Dec 2006 - links to Alan Fozard's Project Summary and David Pawson's performance chart added.
Page updated 19th April 2006 - Power-weight diagram added.
Page updated 15th February 2005 - Feb05 version of post-FDC drawing added