Some 200 acres (81 ha) in total between the island and the mainland were used for docks, quays, sidings and other facilities.

The No.1 dock, the first dock that was built, is 3,400 by 1,100 feet (1,040 by 340 m) and covers about 70 acres (28 ha).

The western end of the first dock is divided into two arms by a projecting Mole.

No.
1 dock has a full width of 1,600 feet (490 m) at the eastern end, so the largest vessels could swing even when the tips and quays were fully occupied.

There was a 700 by 100 feet (213 by 30 m) graving dock (dry-dock) at the north-east corner of this dock but due to the Waterfront development in the 1990s, this has been filled in.

This commercial graving dock was capable of handling the largest vessels of the day.

In 1893, to the east of this, there was a timber pond of 24 acres (9.7 ha) connected to No.1 dock by a short channel almost parallel with the then existing dry-dock but this link was later severed and part of its length converted to another dry-dock and the pond beyond dispensed with and filled in to make way for the necessary high-level rail viaducts and embankments run to the No.2 dock coal hoists.
 The remaining dry-dock, minus its floatable caisson, is still flooded with the waterline commoned with that of the two docks (July 2017).
By 1901 with No.2 dock in use, a second timber pond was included north of the dock.
It was partly backfilled after 1960 but intersected by the docks road level crossing (Wimborne Rd)from Cadoxton to the Bendricks.
This is the single line railfreight link from Network Rail's Cadoxton station to the No.2 docks quays and south-side rail infrastructure and includes a 180° curve from north-west to south-east side of the dock, this now being the only rail access to the entire docks area and serving remaining sidings on the Sully Moors industrial complex, Dow Corning silicone plant and intermodal railfreight traffic (2017).

There are vertical walls where the fixed and movable tips were installed, and between the tips the north wall of the dock had slopes of 1.75 to 1.

This made it easier for ships to come alongside and reduced the amount of overhang needed for tipping.

It also allowed overlap of vessels lying at the tips.

Strong freshwater springs were encountered when sinking the foundations of the No.10 coal tip.

The water was piped to a cast-iron cylinder sunk into the foot of the tip, then pumped up for use by the steam locomotives and the new town of Barry.

Two of the Mole sides are sloped whilst the south-east face is vertically walled.
Originally three sides of the Mole served coal hoists and their related rail sidings linking them and there were cranes on the south-east face, also rail-served.
The former hoist brick-faced plinths are still present (2017) around the north-west and east faces as are those on the rest of the two docks.
In the twilight years of tanker unloading for the William Cory (Powell Duffryn) oilworks, short footbridges were provided from the Mole for works staff to access the brick plinths for the purpose of handling the flexible tanker oil discharge piping and supports and it was not unknown for rail tank wagons to be in use on the siding serving the north-west Mole face.

The bottom of the dock is 20 feet (6.1 m) below mean sea level.

Due to the nature of the strata under the dock there was no need to puddle the bottom of the dock to prevent water from seeping out and damaging the surrounding lands.

The No.2 dock, (often referred to as the "New dock") to the east of No.1 dock, was open and in use by 1898.

The first ship to enter No.2 dock was SS Solent when it opened without ceremony on 10 October 1898.

John Jackson, a veteran of several major dock and harbour projects including the piers and foundation for Tower Bridge, London, the new Dover Harbour and part of the Manchester Ship Canal, was the contractor for the expansion.

No.2 Dock is 3,338 feet (1,017 m) long and 400 to 600 feet (120 to 180 m) wide, connected to No.1 Dock via a narrowing channel from west to east, was latterly bridged by a hydraulically-operated road/rail sw
Some 200 acres (81 ha) in total between the island and the mainland were used for docks, quays, sidings and other facilities.
The No.1 dock, the first dock that was built, is 3,400 by 1,100 feet (1,040 by 340 m) and covers about 70 acres (28 ha). 
The western end of the first dock is divided into two arms by a projecting Mole.
No. 1 dock has a full width of 1,600 feet (490 m) at the eastern end, so the largest vessels could swing even when the tips and quays were fully occupied.
There was a 700 by 100 feet (213 by 30 m) graving dock (dry-dock) at the north-east corner of this dock but due to the Waterfront development in the 1990s, this has been filled in.
This commercial graving dock was capable of handling the largest vessels of the day.
In 1893, to the east of this, there was a timber pond of 24 acres (9.7 ha) connected to No.1 dock by a short channel almost parallel with the then existing dry-dock but this link was later severed and part of its length converted to another dry-dock and the pond beyond dispensed with and filled in to make way for the necessary high-level rail viaducts and embankments run to the No.2 dock coal hoists.  The remaining dry-dock, minus its floatable caisson, is still flooded with the waterline commoned with that of the two docks (July 2017). By 1901 with No.2 dock in use, a second timber pond was included north of the dock. It was partly backfilled after 1960 but intersected by the docks road level crossing (Wimborne Rd)from Cadoxton to the Bendricks. This is the single line railfreight link from Network Rail's Cadoxton station to the No.2 docks quays and south-side rail infrastructure and includes a 180° curve from north-west to south-east side of the dock, this now being the only rail access to the entire docks area and serving remaining sidings on the Sully Moors industrial complex, Dow Corning silicone plant and intermodal railfreight traffic (2017).
There are vertical walls where the fixed and movable tips were installed, and between the tips the north wall of the dock had slopes of 1.75 to 1.
This made it easier for ships to come alongside and reduced the amount of overhang needed for tipping.
It also allowed overlap of vessels lying at the tips.
Strong freshwater springs were encountered when sinking the foundations of the No.10 coal tip. 
The water was piped to a cast-iron cylinder sunk into the foot of the tip, then pumped up for use by the steam locomotives and the new town of Barry.
Two of the Mole sides are sloped whilst the south-east face is vertically walled. Originally three sides of the Mole served coal hoists and their related rail sidings linking them and there were cranes on the south-east face, also rail-served. The former hoist brick-faced plinths are still present (2017) around the north-west and east faces as are those on the rest of the two docks. In the twilight years of tanker unloading for the William Cory (Powell Duffryn) oilworks, short footbridges were provided from the Mole for works staff to access the brick plinths for the purpose of handling the flexible tanker oil discharge piping and supports and it was not unknown for rail tank wagons to be in use on the siding serving the north-west Mole face.
The bottom of the dock is 20 feet (6.1 m) below mean sea level.
Due to the nature of the strata under the dock there was no need to puddle the bottom of the dock to prevent water from seeping out and damaging the surrounding lands.
The No.2 dock, (often referred to as the "New dock") to the east of No.1 dock, was open and in use by 1898. 
The first ship to enter No.2 dock was SS Solent when it opened without ceremony on 10 October 1898.
John Jackson, a veteran of several major dock and harbour projects including the piers and foundation for Tower Bridge, London, the new Dover Harbour and part of the Manchester Ship Canal, was the contractor for the expansion.
No.2 Dock is 3,338 feet (1,017 m) long and 400 to 600 feet (120 to 180 m) wide, connected to No.1 Dock via a narrowing channel from west to east, was latterly bridged by a hydraulically-operated road/rail sw
Barry Docks