Prof. Bill Hall – Papers and Locomotive Simulation Software

The AST Trust is grateful to Mrs Mary Hall, the widow of the late Bill Hall for granting permission to make available for download copies of her husband’s steam locomotive simulation software suites Perform and Perwal. The group is also grateful to his daughter Janet for providing us with photos of her father and some of his files, some of which have been made available for download.

Professor (Bill) Hall F. R. Eng., F.I.Mech.E. was Professor of Nuclear Engineering at the University of Manchester (England), and took a leading role in the early development of nuclear power in the UK. He was also a devotee of the Ravenglass and Eskdale Railway for the benefit of whose members he developed his software packages.

Bill died in 2003 at the age of 80 before he was able to complete a new program with which he intended to simulate locomotive combustion systems. He discovered the task to be profoundly difficult and declared the steam locomotive’s firebox more complex to model than a nuclear reactor.

An obituary to Bill Hall was published in the Guardian Newspaper on 8th Oct 2003 – see [A PDF copy of the text is available here.]

Bill developed two software packages – a simpler one called “Perform” and a supplementary one called “Perwal“. “Perform” uses a simplified “generic” simulation of valve events whilst “Perwal” incorporates an algorithm that more accurately predicts valve events based on the use of Walschaerts valve gear (the valve gear’s geometry being defined by the user).

In addition to programs themselves, some of Bill’s papers are also available for download, two of which present the mathematical derivations used in his Perform program.

Software downloads are offered in Zipped format as follows:

Guidance on use of the software is offered on a separate page of this website.

Bill Hall’s paper are offered in PDF format as follows:

Note: Dr Allan Wallace has proof-read “Predicting Locomotive Performance” and has found a few minor typographical errors in some of its equations. Based on Allan’s advice, Chris Newman has prepared a corrected version of the paper which can be obtained by writing to and requesting a copy.

Allan Wallace’s own valve gear simulation software can be downloaded from his own website at

Other simulations programs include:

  • Two spreadsheets (one for Walschaerts simulation, the other for Stephensons) have been created by Don Ashton and downloadable from his website.
  • Several programs covering a variety of valve gears has also been created by Charles Dockstader of the USA and are downloadable from his website.
  • Jamie Keyte of the 5AT Group is in the process of developing a new steam loco performance simulation package which he has appropriately named “STEAM” (see separate page of this website).