Question: How many of the posts were in an east-west alignment?
About the article "Stonehenge", section "Before the monument (8000 BC forward)".

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The tunnel construction project required excavation of 2 million tons (1,800,000 metric tons) of rock.
On March 16, 1853, "Wilson's Patented Stone-Cutting Machine" (a tunnel boring machine) was used; it failed after excavating 10 feet (3 m) of rock.
Tunnel builders resorted to hand digging, and later used the Burleigh Rock Drill, one of the first pneumatic drills.
Construction also featured the first large-scale commercial use of nitroglycerine and electric blasting caps.
Digging the Central Shaft also allowed workers to open 2 additional faces to excavate: once the shaft was complete in 1870 workers dug outwards from the center to meet the tunnels being dug from the east and west portals.
Engineers built a 1,000-foot (305 m) elevator to hoist the excavated rock from the Central Shaft.
One of the many engineering challenges posed by the project was getting the proper alignment between the four tunnel segments that were being dug: the east and west portal tunnels, and the two tunnels dug outward from the central shaft.
Engineers cleared a path through the forest over the mountain, and strung a straight line from the east to west portals, through "sighting posts" on the east and west peaks of Hoosac Mountain.
Repeated surveys verified the line ran true between the posts, and steel bolts were installed at fixed intervals along the line.
On December 12, 1872, workers opened the east portal tunnel to the Central Shaft-dug tunnel, which were aligned within nine sixteenths of an inch (1.4 cm), a tremendous engineering achievement at that time.
On November 27, 1873, the remainder of the tunnel was opened to the west portal tunnel.
Lewis Cuyler of the Hoosac Tunnel Museum Society described the project as the 'fountain-head of modern tunnel technology.
'The American Society of Civil Engineers made the tunnel a Historic Civil Engineering Landmark in 1975. 
The following were trading posts owned by the Dutch East India Company and the Dutch West India Company, presented in geographical sequence from west to east: 
Before the monument (8000 BC forward).
Archaeologists have found four, or possibly five, large Mesolithic postholes (one may have been a natural tree throw), which date to around 8000 BC, beneath the nearby modern tourist car-park.
These held pine posts around in diameter which were erected and eventually rotted "in situ".
Three of the posts (and possibly four) were in an east-west alignment which may have had ritual significance; no parallels are known from Britain at the time but similar sites have been found in Scandinavia.
Salisbury Plain was then still wooded but 4,000 years later, during the earlier Neolithic, people built a causewayed enclosure at Robin Hood's Ball and long barrow tombs in the surrounding landscape.
In approximately 3500 BC, a Stonehenge Cursus was built north of the site as the first farmers began to clear the trees and develop the area.
An older alignment of US-20 ran about south of the current section east of Laurel.
This alignment went due east from Laurel, passing just north of Dixon and Allen, then headed north to the current alignment along Nebraska Highway 9. 
Another segment was completed from Canfield to Bowden just east of Elkins and was dubbed the "racetrack" for its vast improvement over the old alignment and its isolation from other four-lane highways.
A northern bypass of Elkins was to connect the two segments of Corridor H, however, it was never constructed as the segments east of Bowden were met with intense opposition.
Meanwhile, an alignment following U.S. Highway 33 to Seneca Rocks and then WV 55/VA 55 to Strasburg, Virginia was favored within the West Virginia Department of Transportation.
In 1981, the West Virginia Department of Transportation began planning for a new alignment east of Bowden along U.S. Highway 33 and WV 55/VA 55.
A Draft Environmental Impact Statement (DEIS) was issued.
Funding issues, however, caused the project to be put on hold until 1990.
No Final Environmental Impact Statements or Record of Decisions were completed.
In 1990, the project was resurrected and a reevaluation of the Corridor H alignment east of Bowden was conducted.
A new DEIS was prepared and all corridors considered in the 1981 DEIS were studied equally.
Scoping meetings were held that October.
The purpose and need documentation was completed in March 1992 and a Corridor Selection Draft Environmental Impact Statement (CSDEIS) was completed in October.
In 1993, a revised EIS was published with a new route to go north from Elkins to Moorefield and then into Virginia.
Many citizens, however, felt that improving existing routes would be a better alternative.
Of the 4,000 comments written in 1995 at public meetings, over half opposed the new Corridor H alignment.
They cited the damage to two national forests, 41 streams, historical sites, Civil War battlefields, farms and Main Street businesses.
For some, the costs outweighed the benefits.
In October 1994, an Alignment Selection Draft Environmental Impact Statement (ASDEIS) was issued.
The DEIS focused on alignment selection within the preferred corridor identified within the CSDEIS.
In April 1996, a Federal Environmental Impact Statement (FEIS) was issued that consisted of a revised version of the ASDEIS along with some of the CSDEIS.
In September, a Record of Decision was issued on the preferred alignment east of Bowden.