(New bridge in approximate location)
(Indication of Thamnop Ro on French map of 1687)
Click map to enlarge
Text, photographs & map by Tricky Vandenberg - May 2009
Reviewed July 2011, June 2012
(Example of a weir on the Noi River)
Thamnop is Thai language for a weir or dam. Likely the word "Ro" in "Thamnop Ro"
refers to the area "Hua Ro" at the north-eastern point of Ayutthaya's city island. This area
was called Hua Ro (literally Wait Head) likely for the reason people in the Ayutthayan
era had to wait at the landing near
Wat Mae Nang Plum to be ferried to the “Noblemen
Landing", the second official boat landing in connection with the
Front Palace, the seat of
the viceroy or Uparat (the first official landing being near the Grand Palace). Ban Hua Ro
was a village area on the north bank of the
Lopburi River.

Thamnop Ro was a kind of weir made of wooden beams positioned in the water to
break the speed of the river in order to prevent damage to the embankments. Thamnop
Ro was situated at the confluence of the old Lopburi River with the
Front City Canal or
Khu Khue Na, in front of the today defunct
Maha Chai fortress. The Thamnop Ro
Bridge derived its name from this water speed breaker.

Phraya Boran Rachathanin writes in his work "Tamnan Krung Kao" that the weir was
built at the time a connection canal was dug through the northeastern land bridge between
the (old) Lopburi River and the Front City moat, because the river tended to run straight
south and the loop (ox-bow) around the city would become shallow. The weir was
constructed in the period after the fall of Ayutthaya in 1569, when Maha Thammaracha
(r. 1569-1590) reviewed the defenses of Ayutthaya around 1580. The causeway bridge
was built on top of the heavy wooden beams of the weir. [1]
(Visualisation of the canal dug after the fall of Ayutthaya in 1569)
In an earlier work, the “Testimony of the king at Wat Pradu Songtham: Documents from
the palace”, exists another version. Here is stated that the Burmese besieged the city of
Ayutthaya in 1556 AD (918 CS) during the reign of Chakkraphat (r. 1548-1569). In an
attempt to conquer the city, the Hongsawadi army drove logs in the water, filled the area
in with earth and made a bridge across the waterway. After the war the causeway was
kept as it was convenient to have a bridge into the city. [B]

Point of discussion here, is the year of the occurrence of the event, which should be likely
read as 1568-69, being the year generally accepted by scholars as the first fall of
Ayutthaya to the Burmese. But there are more contradictions.

At the time of the Burmese attack in 1568-69, the
eastern city wall was west of Khlong
Makham Riang (aka Khlong Nai Kai), being the eastern defense moat of the city. The
northeastern corner of the city wall ran from
Pratu Khao Pluak towards - where is
today - the confluence of
Khlong Ho Ratanachai and Khlong Makham Riang. The whole
northeastern corner was outside the city walls and a land bridge existed towards Phaniat
area. This land bridge was defended by an advanced stockade bearing already at that
time the name Pom Maha Chai (RCA 35). The Front City moat was a secondary
defensive moat.

The Burmese built three causeways in 1569; one in front of
Wat Fang (Wat Khwang),
another in front of Bang Ian village (village at that time outside the city walls) and the last
at the corner of Kaeo Island. The Royal Chronicles of Ayutthaya do not mention any
attack on the Maha Chai Fort and the northeastern land bridge, neither speak about the
construction of a causeway in that place. The Burmese Chronicles are also
silent. Anyway it seems logical that the Burmese constructed the causeways out of sight
of the main fortifications of
Pom Phet and Pom Maha Chai. [3]

When the inventory of all the troop supplies ordered by the King was completed,
the King of Hongsawadi had preparations made for attacking the Capital and
ordered causeways laid extending in towards the front ramparts of the city from
three points; from the positions of the Uparat the first was to be laid extending in
to Fang Monastery and a second to Ian Village, and from the positions of
the King of Ava a third was to be laid extending in to the corner of Kaeo Island.
In laying the earth in towards the city the men of Hongsawadi constructed shields
and set them up running in towards the city to protect themselves from firearms,
and they heaved the earth on ahead over the shields.

Another possibility could be that "Testimony of the king at Wat Pradu Songtham"
refers to the war with the Burmese of 1563-64, but this is very unlikely as the old
scriptures put the event in a dragon year (Pi Marong) and none of the chronicles make an
indication of building a causeway to invest the city of Ayutthaya.

In my conclusion, the version regarding the weir given by Phraya Boran Rachathanin in
Tamnan Krung Kao looks the most plausible. The causeway bridge was built on top of
the heavy wooden beams of the weir, functioning as support, while the weir was
related to the digging of the (150 meter short cut) through the northeastern land bridge for
defense purposes after the 1568-1569 war.

The Tamnop Ro Bridge stood next to the Maha Chai Fort (as can be seen on Bellin’s
map) near the store house of the Front Palace. The bridge, paved with planks, was 6
meters wide and allowed the passage of boats in the middle. On both sides there were
steps for descending the slope down to the bank. The bridge must have been strong as
carts, elephants and horses could pass it. The crossing was only possible with an official
order and strictly controlled. For this purpose there was a manned guard pavilion beside
the bridge. [2]


[1] ตำนานกรุงเก่า - Tamnan Krung Kao - Phraya Boran Rachathanin (1907) - page
[2] พรรณนาภูมิสถาน พระนครศรีอยุธยา เอกสารจากหอหลวง
(ฉบับความสมบูรณ์) - Geographical description of Ayutthaya: Documents from the
palace - Dr Vinai Pongsripian - Bangkok (2007) - page 82.
[3] The Royal Chronicles of Ayutthaya - Richard D. Cushman (2006) - page 62
/ Source: Thonburi fragment (1779) Khurusapha (1963).
(Thamnop Ro on de Courtaulin's map)
(Thamnop Ro on Kaempfer's map)