A tyre burst might have led to the March 19 bus accident on Dhaka-Mawa-Bhanga Expressway that killed 19 people, reveals a report by the Accident Research Institute (ARI) at Bangladesh University of Engineering and Technology (BUET).
Refuting a previous probe report that cited overspeed caused the accident, the ARI doubted that the expressway has many safety lapses as 222 accidents with 264 fatalities occurred on this expressway between June 2022 and March 2023.
There was no continuity in roadside railing which is a major inconsistency and deficiency for such a costly high standard expressway, it said, recommending undertaking an urgent Road Safety Audit (RSA) to identify safety lapses.
It suggested that only construction of high-standard capital-intensive infrastructure is not enough to ensure safe mobility; there is a need for matching expressway-worthy fit vehicles, competent drivers, standard road safety devices and most importantly well enforced safe and disciplined traffic operating conditions.
It also suggested formulating policy to make Pre-Safety Audit mandatory before building any highways and expressways.
ARI Director Dr Shamsul Haque made the disclosure along with suggestions while presenting an investigation report at a press briefing on Sunday.
He said the absence of skid marks on the pavement suggests that the crash was sudden and could be triggered by a tyre burst and not due to brake failure.
Besides, duty rosters show that the driver had the opportunity to rest and fatigue could not be considered a contributory factor. Based on the speed tracking data, he was not speeding. It said that there was no evidence that before the crash driver hit a pedestrian, he said.
The ARI analysed the speed profile of the bus (Emad Poribahan) by collecting data from the Akash Track Me server and the Event Data Recorder (EDR), and prepared a superimposed speed profile on geographical conditions that showed that throughout the trip, the driver maintained speed matching the roadway operating conditions.
“Inferring from the consistent speed profile on the expressway section, it is reasonable to conclude that the driver’s response pattern was attentive while driving on this section. He maintained a steady speed below 90km per hour. The speed was 79km per hour before the derailment. Note that the posted speed limit is 80km per hour on both highways and expressways,” he said.
The ARI found that mechanical or brake failure was not a probable cause of the crash. Though the driver was driving with a medium category licence, he fulfilled the requirements to get a heavy vehicle driving licence.
The bus was a new one - apparently the interior and exterior of the bus were in good condition and most of the seats did not disjoint from the floor. Weather is not a causal factor while rain intensity and smooth pavement surface do not support causes of hydroplaning, the findings said.
Was the driver in fatigue due to overdriving?
According to the driver roster (online and offline) as well as the vehicle GPS tracker data, the investigators found that in the last around 38 hours since 6pm on March 17, the driver drove for 20 hours (four trips) including the trip that led to the accident.
Within the 20 hours of driving, there were two long (6.5 and 9 hours) trips along with several short breaks. Moreover, the driver was on leave from March 14 morning to March 17 evening.
The stat indicates that the driver got a sufficient gap to rest before the trip.
Why so many fatalities?
The investigative report says that the bus derailed right before a culvert which eventually led the bus to hit the top edge of the culvert’s concrete wing-wall. Consequently, the huge energy caused the bus to smash and squeeze its front part. As there was no room for front seat occupants such as the driver, his assistant, supervisor, and front seat passengers, this impact resulted in 14 spot deaths and many severe injuries.
There was no protection on the road for derailed vehicles to restrain them on the carriageway, and to avoid directly hitting the hazard. If there was protection on the roadside in the form of guard rail, that ancillary impact could have been avoided. There may not be that many fatalities. This again implies that the appropriate guard rail is needed for this section of the road which was missing.
“For better understanding, guard rails can be compared with seat belts in a vehicle. As seat belt restrains a passenger from being thrown away from the seat in case of impact, guard rails do the same for derailed vehicles to keep them on the road. The standard requires this safety element when the height of the road embankment exceeds six feet, considering the high degree of hazard,” the report says.
Recommendations
The BUET recommended that every vehicle especially, commercial vehicles must have a tracking device which can effectively monitor the driver's driving speed.
It suggested installing standard digital variable message signage (VMS) to impose condition-responsive speed limits at the expressway.
The report recommended that the Bangladesh Standards and Testing Institution (BSTI) should be equipped with both destructive and non-destructive testing facilities for checking the quality of imported tyres and tyre-related components.
The government should recast the Crash Investigation Committee (AIC) comprised of independent professionals with technical expertise, while excluding members from the Bangladesh Road Transport Authority (BRTA), police, and Roads and Highways Department (RHD).
