To preserve the durability of bridges, Road Transport and Bridges Ministry last week issued a set of directives to the Roads and Highways Department (RHD) to stop sand lifting near bridges.
The RHD was asked to take steps, if necessary, to evict balu mahals (an area from where sand is lifted) near bridges and illegal brick kilns that block the navigability of rivers, both of which affect the strength of bridges.
The ministry issued the directives amid growing news reports of sand lifting posing a threat to various important bridges.
The Daily Star published at least three reports in the last one month alone. The reports cited mindless sand extraction threatening five bridges on the Manu river in Moulvibazar and Titas and Meghna rivers in Brahmanbaria.
According to the Balu Mohal O Mati Babosthapona Ain (Sand Fields and Soil Management Act), 2010, sand lifting is not allowed within 500 metres of any bridge.
However, the reports found evidence of sand extraction and stockpiled sand near bridge areas posing a threat to the structures.
Local influentials continue to extract sand by “managing” some unscrupulous local authorities with “monthly benefits”, while some others lift sand at night to dodge authorities, our correspondents found.
DIRECTIVES by the ministry
The ministry letter said sand extraction and balu mohals damage bridges of the RHD. If the situation persists, affected bridges will keep incurring damage, which would reduce their durability due to the scouring of riverbed near the piers.
Another issue comes with filling river areas to keep bricks at “eit mahals” near bridges. Steps need to be taken to stop this, the letter said, for the sake of both navigability of rivers and durability of the bridges.
Vigilance has to be ensured so that none can lift sand or develop balu mahals near bridges, the letter added.
If necessary, measures to evict brick kilns erected in these locations should be undertaken, the letter also said.
The ministry also asked to ensure proper drainage of rain water so that trapped water cannot cause damage to bridges, culverts and roads.
There are 4,404 bridges and 14,814 culverts in RHD’s 22,096 kilometers road network across the country, according to the 2018-19 annual report of the Road Transport and Highway Division.
WHY IS SAND LIFTING A SERIOUS ISSUE?
Shishir Kanti Routh, additional chief engineer of RHD, said when a bridge is constructed, it blocks the natural flow of a river, which is why scouring -- weakening of the soil underneath the piers -- takes place.
This is why a hydro-morphological study is conducted during the design stages of a bridge to keep scouring at a minimum and protect piers.
However, sand lifting near bridges increases the probability of deeper scouring and, in turn, increases the vulnerability of bridges.
Asked how the RHD takes steps against sand lifting,, Shishir said RHD officials monitor it and inform local administration.
Contacted, RHD Chief Engineer Ashraful Alam said in many cases, local RHD officials are unable to do carry out this task due to pressure from influential quarters.
“However, these ministry directives will embolden them (local officials). We will now seek more help from the administration and police. We are going to intensify our effort with the new directives,” Shishir Kanti Routh said.
THE BALU MAHAL SITUATION
There are 707 balu mahals across the country. Of them, 126 are in Dhaka division, 200 in Chattogram, 75 in Rajshahi, 94 in Sylhet, 65 in Rangpur, 57 each in Khulna and Barishal and 33 in Mymensingh division, according to the Land Ministry.
Deputy Commission office lease out these balu mohals to interested parties. However, many people lift sand from undesignated places too, some of these places too close to bridges.
Shishir Kanti Routh said the local administration, in many cases, gives lease of balu mohal near bridges without understanding its risk.
“So, they [local administration] should take consent from us [local RHD officials] before issuing a lease,” he told The Daily Star.
He said issues in a single bridge due to sand lifting can collapse a road network consisting of 50 to 100 bridges.