The structure of a scrum

Author: Bill Harvey FIStructE

Date published

1 November 2019

Back to Previous

The structure of a scrum

Blog
Date published

1 November 2019

Author

Bill Harvey FIStructE

Author

Bill Harvey FIStructE

Bill Harvey FIStructE is a designer of bridges and Structural Award-winning bridge innovations. To mark the Rugby World Cup final, here he describes the structure of a scrum.

Structure or machine?

Is a scrum is a structure or a machine? Partly it depends whether it’s a good scrum or a bad one. The start of a good scrum should be relatively stationary, which suggests a structure.

When I think of a scrum I think of an arch bridge: the two front rows form an arch. Arches normally work by carrying load from the top out to the edges and downwards. However, in a scrum, much of the force begins from the feet of the participants.

How an arch works, how a scrum works

The thing that allows an arch to carry concentrated loads is an ability to re-channel forces in different directions, though they have to stay in the arch. 

In a scrum, the arch effectively comes to a point at the top, where the two teams meet shoulder to shoulder: 

If the compression gets too low, the point of contact at the top tends to move upwards – that is resisted by the necks of the men in the front row. 

If compression gets too high, the point of contact wants to move down. The resistance to the drop comes from the backs of the front row, and from where they place their feet – if they can move their feet forward a little it will help. Trouble with that is, it tends to arch their backs, and if a big push comes on there is a risk of injury.

The structure of rows

In the front row the heads are under tightly linked arms. There is no real cross link at the back end where numbers four and five lock, except their own arms and those of the wing forwards beside them. 

Just like a brick wall under compression, there is a tendency to split apart and that lets the second row through into the front.

Related Resources & Events

Blue abstract blocks

Dr Mike Cook’s 2020 Gold Medal address

In an inspiring online lecture, Dr Mike Cook presented his compelling vision for the future. He argued that structural engineers have a vital role to play in reducing the impact of carbon in the built environment.

Date - 24 September 2020
Author - IStructE
Blue abstract blocks

Three tools for handling microinequalities

In this blog post, Dawn Bonfield builds on her recent piece, microinequalities – what they are and how to spot them. She explains how three different tools can be used to counter microinequalities.

Date - 11 August 2020
Author - Dawn Bonfield
Blue abstract blocks

Microinequalities – what they are and how to spot them

In this blog post, Dawn Bonfield discusses microinequalities. She explains what they are and how they disproportionally affect people in minority or under-represented groups.

Date - 11 August 2020
Author - Dawn Bonfield