Analysis of DPR for the Sarakki Flyover at the Kanakapura Road-ORR junction
July 04, 2023 Vaidya R
The junction of the Outer Ring Road (ORR) and Kanakapura Road at Sarakki is one of the busiest junctions in Bengaluru and there have been repeated calls from commuters and the traffic police to ease the traffic. BBMP proposed a flyover at that junction to ease the traffic. A Detailed Project Report was prepared to understand the traffic flow in the area, the need for the flyover, the alignment of the flyover and how it would solve the issue of the traffic. You can find the DPR here.
What does the DPR propose?
The DPR proposes a flyover along the outer-ring road from Kadirenahalli junction/Geological Society of India till 33rd Main Road, JP Nagar, near Sindhoora Convention Centre.
The DPR was prepared in late 2019/early 2020 and the estimate at that time was Rs. 119.58 Cr, of which construction itself was to cost Rs. 69.92 Crore. Consultations, shifting of utilities, land acquisition, GST etc make up the remaining Rs. 50 Cr.
The report notes that the Green line of the Metro passes through Kanakapura Road at 13.5m. The report does not mention the height of the flyover and what would be the height restriction for vehicles that would pass below the flyover. The flyover is also skewed towards Kadirenahalli with a smaller span towards JP Nagar. Details about the clearance provided to the metro and for vehicles below would have been useful but the report does not seem to mention that.
Justification for the flyover
The main justification for the flyover is the high volume of traffic that passes through the junction and the delay at the junction. A traffic study done in December 2019 found that it takes between 20-25 minutes to go from Kadirenahalli junction to Puttenahalli Junction along the ORR.
What the traffic study shows
The traffic patterns and volume was studied in Dec 2019. On 3rd Dec 2019, a Tuesday, the traffic was observed and counted over a 15 hour period from 7 AM to 10 AM. Vehicles recorded were categorised by type of vehicle and classified based on timing and direction of movement during this time.
The vehicles were classified as two-wheelers, cars, autos, buses, light commercial vehicles (LCVs), tractors, trucks, hand-drawn, animal drawn vehicles and bicycles. The study was conducted at three locations – Sarakki junction (Kanakapura Road-ORR junction), Ilyas Nagar junction and J.P Nagar 35th Main Road junction on ORR.
While the traffic movement was studied for 15 hours, pedestrian movement was studied only during peak hours. Vehicle queuing delay and length were also calculated, under both automatic and manual signaling.
The vehicles were counted in units of Passenger Car Units (PCU) based on the weightage given to different types of vehicles as below:
The study over 15 hours found that the total PCUs was 1,72,902 (1,53,525 vehicles) of which 148 were slow-moving units (hand or animal drawn and bicycles); rest were all motorized vehicles.
The peak traffic was observed from 7 PM to 8 PM. However, except for 8 PM to 10 PM, the hourly traffic during the rest of day was between 60-99% of the peak traffic. The junction was seen to handle a heavy traffic load during 13 of the 15 hours studied.
In terms of split, 33% was West to East traffic (Kadirenahalli towards JP Nagar), 29% was East to West (JP Nagar to Kadirenahalli). The direction the flyover was proposed was seen to be handling 60% of the traffic. As expected, 45% of the traffic was two-wheelers, followed by cars and autos at 16% and 15% respectively.
The queue length at peak hours was also seen to be around 150m, reaching 170m from Kadirenahalli side between 5 and 6 PM. The perpendicular traffic along Kanakapura road fares worse, also because of less carriage width than ORR. The average queue length reached 190m during peak hours.
The signal was seen to be operated manually during 9 of the 12 hours the queuing survey was done.
Justification for the flyover
The Indian Roads Congress (IRC) guidelines specify the following guidelines to decide when a junction needs a grade-separator like a flyover or an underpass.
- When the total traffic on all arms of the intersection exceeds 10,000 PCUs
- Stopping time at the signal exceeds 120 secs.
- Estimated traffic over the next five years is in excess of the capacity of the junction.
The study found that the average PCUs per hour was 12,315 PCUs per hour at peak. Based on the queuing study the study concludes that the volume at the intersection is too high and the junction cannot be cleared in a short time. They also note that the “general trend” is for “population increase and vehicle increase”. Based on these reasons, the study recommends a grade-separator from Kadirenahalli to JP Nagar side, along the ORR.
Specifications of the flyover
The flyover is expected to have 4 lanes, 2 in each direction. The width of each lane would 3.75 m. Along with median and kerb the total width is specified to be 17m.
The exact length of the flyover from ramp to ramp is not mentioned anywhere. But going by the junctions mentioned it would be between 1-1.2 km long. The flyover cost would also include 327.5m of land acquisition.
Environmental costs and mitigations
The flyover is expected to result in the chopping down of 97 trees along the outer ring road. The proposal plans to offset these through “compensatory afforestation” measures at a 2:1 ration, i.e. 194 trees planted elsewhere. The report does not mention where the 194 trees are to be planted. While there are few full grown trees in this junction, most likely because the big ones were likely all chopped off for the metro as well as for the ORR, without anyone to hold them accountable it is questionable whether and where the compensatory afforestation will take place.
As for pollution, the report acknowledges that the air pollution would go up during the construction, but with unhindered movement of vehicles they expect it to come down after construction.
To mitigate the pollution, they plan to ensure that vehicles that bring materials to the site would be covered. Vehicles are also expected to unload their contents only during night time, especially during settlements. How the latter would solve any pollution is not clear.
While the mitigation measures sound good to hear, the proposal writing authorities might not be the ones who are running the construction activities. Without any grievance redressal mechanisms there would be no one to hold them accountable, and the report does not mention setting up any such mechanisms either.
Sarakki junction where Kanakapura Road intersects the ORR is one of the busiest junctions in South Bengaluru and urgent measures are called for to resolve the traffic. The proposed grade separator might resolve the bottleneck at the junction and allow relatively freer flow of traffic for Kanakapura road.
However, local traffic issues at the neighbouring junctions at ORR are not mentioned or addressed by the report. While Ilyas nagar is bypassed, the Kadirenahalli junction where traffic between Kumaraswamy Layout/Dayananda Sagar Institutions and Banashankari have rendered the Kadirenahalli underpass ineffective will continue to remain a bottleneck, especially for traffic from JP Nagar towards Deve Gowda Petrol Pump. In fact, a flyover upstream might render this junction the next bottleneck.
On the other side towards JP Nagar, there are at least two signals or controlled junctions between Sindhoora Convention Hall and the Puttenahalli underpass. Whether these junctions will be closed for traffic management or not is not mentioned. With the flyover up the road, these minor junctions could potentially be the next traffic hotspots.
This is unfortunately, the main issue with using grade separators as a piecemeal solution to address the traffic at one junction. While flyovers and underpasses are not new to this part of the city, they have only managed to shift the bottleneck to the next junction. In fact, it could be argued that the heavy traffic and long wait time at the Sarakki junction is a result of the Puttenahalli underpass on the JP nagar side, and the Deve Gowda Petrol Pump flyover and the Kadirenahalli underpass on the Banashankari side.
While the report analysed the traffic patterns and numbers, the assumption is that vehicle numbers are expected to go up with more traffic. There was no mention or analysis of how that can be avoided in the first place.
While it was observed that the traffic signal was manually managed for 9 of the 12 hours they studied, studies to understand whether any change in the signalling, or change in traffic flow can help the junction were not conducted or mentioned. Basically, no alternatives to solve the congestion other than a flyover at that particular junction were considered or mentioned.
Instead of a construction body studying the traffic and proposing a flyover, an independent study needs to be conducted by a body consisting of urban planners and experts in the field. Such a study can look at the traffic as a whole – commuting patterns, places that are contributing to the traffic, and propose long term solutions that can reduce congestion, not just at the junction, but also along Kanakapura Road and Outer Ring Road for longer stretches.