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The Great Pyramid and Transport of Heavy Stone Blocks

January 4, 2013 33 Comments

The Great Pyramid and a new approach for the construction

Transport of Heavy Stone Blocks with Human Power in Ancient Times
Copyright 2012 by Henk J. Koens
                                             
We have all ever wondered how the ancient Egyptians were able to transport the 2.5 million  limestone blocks to build the Great Pyramid. The handling of stone blocks with a weight from one to several tons in such a quantity is a gigantic operation, even in our days.   
Herodotus in “The Histories” (5th century B.C. ) talks about “… machines formed of short wooden planks” used for  pyramid building. [ Editor’s note: read this relevant post about it:  The Pyramid Tales  ]               
Here is author’s interpretation of  “machines formed of short wooden planks“:

What is not understood?

The general idea in the existing literature is that the Egyptians transported the stone blocks on wooden sledges. These sledges were dragged forward by a team of human workers.
However, the efficiency of a sledge transport is extremely low. It required an enormous effort and so many human workers that the working area and the road to the pyramid would be overcrowded. Probably in special situations sledges were used but it is difficult to believe that this was the case for the great majority of transportations.
The idea is that there must have been a more efficient transport system to meet the required building and time conditions.

Is there an alternative?     About the same time Parry(1997) and Mladjov (1998) came up with a revolutionary idea that these stone blocks were transported by rolling . The use of a vehicle on wheels was not an option because the “wheel” was not known to the Egyptians and above all  not solid enough for these heavy loads. But the authors failed to give us a satisfying and practical solution. However, this idea was not new. Already in 1977 an english engineer John D. Bush (The rolling stones) suggested this method and it was earlier described by Vitruvius, an ancient roman architect, in his book “Architecture, vol. X, chapter 2/14” Was there a simple and practical solution?                           We know that the use of rollers for the transport of  heavy loads was an every day technique in ancient Egypt. Therefore upscaling of this proces for large items was a logical thought. The Eyptians did their work with ropes and levers. Furthermore were copper, stone (dolerite) and wood the only available materials. But probably also bronze, a material 2 to 3 times as hard and strong as copper. A tool of bronze has been  found in the pyramid. So simplicity had to be the keyword.

A practical alternative might have been the rolling stone carrier : A device that carries a stone block, consisting of two wooden discs with a stone block inbetween, firmly tied together with a rope (see the next picture)

and a practical solution for a load of 2500 kg (see the next picture):

A disc made of local available materials

A disc could be made of a number of similar shaped wooden circle segments. If copper nails were not available, wedges, wooden pins or a rope could be used to connect the parts.  (see pictures below).

Another tool, especially designed for not uniform big stone blocks, consisted of a disc system in which the stone block was supported by 4 wooden bars, fastened with wedges (see the next picture)

How did it work?

The discs and stone as a whole is a rolling element. With a pair of shafts and holes in the center of the discs the carrier could be pushed and pulled forward by human power or by an animal. The long shafts made it easy to round sharp corners.
The effect of the heavy load is directly transferred to the bottom through the discs. So the center holes did not suffer the heavy load and served only as input for the light pulling force. But even without the shafts the workers could move the stone block by pushing up the discs on both sides (see pictures below)

Transport of a 2.5 ton stone block

On a rigid and plain bottom (wood, stone or bricks) such a system with wooden discs has a friction factor against rolling of  about 0.025.
This value can be determined by model experiments and is known to transport companies that have the experience that large wooden cable reels start rolling down at a slope of slightly more than 2.5 % (1:40), which means that the friction factor is equal to the value of this slope or 0.025.
Therefore the transport of a stone block with a weight of 2.5 tons on a plain surface requires a pulling force of  0.025 x 2500 = 63 kgf (139 lbs). So a team of 6 human workers can easily pull this stone block forward.
In contrast, a wooden sledge with this load has a friction factor of 0.2 to 0.4 and requires a pulling force of at least 0.2 x 2500 = 500 kgf (1100 lbs) !

How many workers were needed to transport this load uphill?

To reach the construction platform of the pyramid there existed a ramp or a spiral road around the pyramid with a slope of about  5% (1:20).
To overcome the gravity component of the load, an additional pulling force was necessary of  5% of  2.5 ton or 0.05 x 2500 = 125 kgf (275 lbs), which makes the total effort 63 + 125 = 188 kgf (414 lbs).
Therefore at the foot of the pyramid 10 workers with a rope were added to obtain the required extra power. With an effort of 188 / 16 or about 12 kgf (26 lbs) per worker, a team of in total of 16 human workers could transport this load uphill (see the next picture).

The transportation and how it was arranged    

Most authors believe that the Egyptians had to quarry and to transport daily 40 stone blocks per hour to meet the required construction period of 20 years.
This means a delivery to the construction platform of one stone block every 1.5 minute. In this time and with an assumed speed of 1.5 km per hour, a transport team could cover a distance of 1.5 / 60 x 1500 = 37.5m. With this transport system it was possible to create  a continuous flow of stone blocks to the construction platform with a distance of 37.5 m between two successive transport teams (see next picture).
It took roughly one hour to transport a stone block over a road (slope 5%) with a length of 1400m from the foot of the pyramid to an altitude of 70m (halfway to the top).

How many carriers were needed?

The distance from the pyramid to the nearby quarries was about 700m, so that the total length of the transport line from the quarry to a construction platform halfway to the top was 1400 + 700 = 2100m. So with an average distance of 37.5 m between two transport teams, a number of 2100 / 37.5 or 56 disc systems were on the road. This means that together with the same number of returning carriers, in this situation a total of 112 were daily in use.

How many transport workers were involved ?

The uphill transportations to a construction platform halfway to the top, required 1400 / 37.5 or 37 teams of  16 workers and the horizontal transportations
700 / 37.5 or 19 teams of 6 workers, so in total
37 x 16 + 19 x 6 = 706 workers. The same number of workers was always on the way back. The returning workers had time enough to do additional jobs on the construction platform and in the quarries. One can conclude that in this case roughly 1412 workers were daily on the road.                                            

How was the carrier loaded in the quarry?

When the quarry workers with their stone or bronze tools were ready with removing the material on both sides of the stone block and underneath, two beams and rollers were placed under the stone block. Then they made a carve on the top backside of the stone block and placed wedges to split it. After splitting it rested on the rollers. Now it could be rolled away from the stone wall and in this position it was possible to give the stone block its final size in accordance with the internal dimensions of the disc.  Both sides of the stone block were accessible now for mounting the discs. (see the next picture)

How many people worked in the quarries?

The “NOVA-experiment” showed us that with a correction for the primitive tools in the early days,
2 workers could carve a stone block in 2 days.
So a production of 40 stone blocks per hour or 320 per day, required a daily manpower of 320 x 4 = 1280 workers.

Delivery and positioning of the stone block

To prevent differences in height in a new to build layer, it was very important that all the stone blocs of that layer had the same thickness (Petrie).
However, the dimensions of the center area of the carrier dictaded exactly the thickness of the stone block.  So this requirement was always met when  the same size of carrier was used.
Unloading the stone block took place with rollers and slanted beams. Afterwards the empty discs were returned to the quarry for the next transport.
If necessary, adjustments could be made. Large fragments were not returned but as much as possible transformed into reusable building elements. Debris was used as filling material. The final positioning of the stone block took place with heavy rams.

General conclusions for this transport system

• The rolling stone carrier was a simple design and made of local available materials. This tool made it possible to transport heavy stone blocks in an efficient way and with human power.
• The carrier was very compact, easy to handle and it could easily round sharp corners.
• With this tool the activities in the quarry can be fully   explained and this tool made it possible to deliver stone blocks with a constant thickness.
• Calculations about the transport capacity and the use of manpower lead to reasonable values.
• This tool could also be used as temporary storage and was an optimal solution for long distance transportations by ship. 

Critical comments

The rolling stone carrier is a rolling object and differs  considerably from a vehicle with wheels. A vehicle with weels (unknown to the Egyptians) has always a shaft with bearings which is not rigid enough to withstand the heavy load of a stone block. The rolling stone carrier had no bearings but only simple discs and was strong enough to transport these loads.
So far no carrier system has been found during excavations, other than some wooden circle segments found by Petrie. However, wood was a valuable material for building and firing, so it is understandable  that not much of this material can nowadays be found. Nevertheless we know that the Egyptians were good craftsmen who could build ships and certainly also carrier systems.

OTHER MYSTERIES

The above mentioned transportations with the rolling stone carrier, only apply for the bulk of the building materials.
There is also the question how the Egyptians transported the extreme heavy granite stone blocks needed for the construction of the king’s chamber and  how they lifted these stone blocks to an altitude of about 60m. There were about 50 items, each with a weight between 50 to 70 tons.
In literature there is also discussion about the type of ramp or upward road that was used by the Egyptians.
What is the answer to these questions?

How were stone blocks of 50 tons and more raised to a high level?

The answer is simple. These heavy objects were placed on one of the first layers of the working platform at the start of the construction of the pyramid. After every new layer they were lifted to the next higher layer until the required level was reached. On the working platform there was place enough for special tools and  extra workers.

How were these stone blocks transported?

These enormous granite stone blocks arrived by ship from Aswan, 1000km to the south of Gizeh. If further transportation took place with a wooden sledge, a number of at least 400 workers would  have been needed. Even with lubrication and a very low friction factor of 0.2 , the pulling force was already as high as 0.2 x 50,000 = 10,000kgf or 22,000lbs !
A disc system of a large dimension (e.g. discs with a diameter of 4m or 13ft) was a far better solution. Because of the higher transport efficiency the labor force could be reduced to 15% and less. This disc system could also be used for the stone lifting proces on the platform and for temporary storage (see pictures below).

How were these heavy stone blocks placed in the transport discs ?

This process required a special wooden tool, consisting of two circle segments connected by wooden bars.  
When the stone block in the quarry was splitted by using wedges, it rested on this tool. Then the workers rolled the stone block away a from the stone wall with levers and ropes. Now it was possible to mount the discs on both ends of the stone block. (see pictures below)

What type of ramp was used?

The step by step method of lifting heavy stone blocks on the working platform of the pyramid, had a great advantage. Because of the low level at the start of the construction of the pyramid, a voluminous and labor intensive ramp was not necessary. Only a short ramp was needed to place these enormous stone blocks on the first layers of the pyramid.