The public works department (PWD) has announced plans to build a guard rail on VIP Road, along Lower Bagjola Canal, three days after a bus fell into it, killing 20 passengers.

“We have discussed ways to avoid a repeat of Friday’s accident. A railing with pillars and steel wires will be constructed on certain stretches of VIP Road,” said PWD minister Kshiti Goswami on Monday.

A guard rail is only one of the essentials missing on the eight-km stretch constructed in the early 1970s. Some of the other problem points are:

Improper alignment: A 400-metre stretch of the road near Kestopur violates the basic principles of road engineering, admitted PWD officials.

According to a senior PWD engineer, the curvature and gradient of the road are faulty. “There’s a sharp bend on VIP Road near Kestopur. The road should ideally be more elevated to ensure safety of the motorists,” he said.

The survey department has brought the matter to the notice of the engineering department several times. “Correcting the alignment will mean relaying the road, which we have done in the Bangur Avenue area,” said another PWD engineer.

Poor skid resistance: High skid resistance is a must for roads where vehicles move fast. VIP Road, however, has a mastic asphalt surface, which is prone to skidding.

“Concrete mixture should have been used in place of mastic asphalt on VIP Road for tyres to get a better grip,” said a civil engineering professor at IIT Kharagpur.

PWD officials said mastic asphalt was used to increase the surface’s longevity. But a spate of accidents has made the authorities consider the possibility of introducing skid-resistant concrete mixture while relaying the surface.

“The repairs on VIP Road are still being carried out with mastic asphalt,” admitted an official.

Excess load: What’s below a road is as important as its surface.

According to experts, the base of a road is prepared keeping in mind the expected load it will bear.

“The forecast of the load on VIP Road was way below the load now. The uneven road surface is a result of the mismatch,” said a PWD engineer.

The department carries out patchwork on the uneven stretches, but that can only be a short-term solution.

Faulty signal system: Traffic signals and signage — informing motorists about speed limit, nature of road ahead — are sorely missed on the airport artery.

“We have installed automatic traffic lights on some stretches. We have plans to overhaul the signal and signage system on VIP Road,” said a senior district police officer.