"Feats of Engineering" Topic

I am trying to determine how long various feats of engineering take. The challenge is I am not trying to determine how long specific historical happenings took but rather the raw formula of:

X men * Y hours = Z distance of _______

Where ______ is various outputs:

light works
medium works
heavy works such as a redoubt
pontoon bridge
wood bridge
repair of a bridge

Can anyone point in a good direction for gathering this sort of general information?

Cheers,

The Bandit

There are British Army "Manuals of Field Engineering" dating from the 1st World War (and perhaps some even ealier) that can be picked up. Some may be available on-line.

The basic man-hours for performing such tasks (using natural materials as opposed to modern purpose built systems) have not changed significantly over the years. I can say that with authority having spent 30 years in the Royal Engineers.

I am in Spain at present but go back to UK on Thursday 28 June, will dig out my copy and check times for the specific works you listed above.

Rod

I have a 1913 book intended for officers "Military Engineering part 111a, Military Bridging – General Principles & Materials" which covers the subject in far too much detail.
eg there are tables for breaking loads on Goverment cordage & commercial cordage.
Section 1 – Reconnaissance includes Fording, Crossing on ice, Boats, rafts or flying bridges, bridging.
Section 11 – Nature & Measurement of gaps to be bridged includes Classification of bridges, Parts common to all bridges, Camber, Ruling dimensions.
Section 111 – Loads on Military Bridges & stresses produced thereby – General case of loads on a supported beam.
Section 1V – Materials
Section V – Accessories required for Bridging Operations
Section V1 – Organisation of working parties

That's the series. There are also ones on various other Field Engineering topics. We used updated, but still very similar, books when I did my Royal Engineer officer training in 1962/63.

Rod

My experience as a former military engineer is that the estimates found in books are reasonable only under "perfect" conditions. When doing any job for the first time I used to multiply the time and/or resource requirements by a factor of 4 to account for lack of training, and the inadequacy of the tools and supplies, and the random effects of weather, rocky earth, etc. It always took longer than what the book said, and sometimes it took even longer than the "x4" multiplier.

Experience can overcome much of the variables. If the same guys do the same job over and over again in the same locations, and those guys are kept well supplied, they get pretty fast.