| Existing situation The image to the right shows the the existing situation at the junction. Vehicles going south to north and north to south travel straight along the bellary road. Vehicles from south going to the west take left on the slip road. Vehicles from west going north from west take left on the slip road. The main conflict is between north-south traffic and vehicles from the west going south towards the city. When vehicles from west heading south towards the city crosses the road, both north bound and south bound traffic has to stop. The palace maidan is to the right of bellary road. 1st main and 18th cross are two other roads in the area. Both sides of sankey road and the western side of bellary road are lined with business. |
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| Ideal
solution If some space to the east of bellary road, on palace maidan was available, then true signal-free fast movement through this junction would have been possible. One such ideal solution is shown in the figure to the right. Simply lift the problematic linkage and ease it into the south bound traffic. The main linkage now has to only deal with merging and exiting traffic. Other variations to the theme, like underpass or a loop that bends backwards etc are also possible. But as idontspam has pointed out acquiring palace lands is not possible. Thus, it is not possible to separate the problematic west-south linkage by physically moving it. |
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| An
idealized alternative One way out is to move the main link iself and that is what, I think, the palike is trying to do. An idealized version of this solution is shown to the right. It is not so much a U-turn as it is going through a circle or roundabout - only, in this half circle, there is traffic at the center of the circle instead of somebody's statue. South bound traffic still has stop to let traffic from west going south, to cross the bellary road. S1 and S2 will be two signals regulating usage of the road. When S1 is green S2 is red and vice-versa. |
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| The bottomline of this design is that the north bound traffic(towards airport) gets continuos free movement by passing over all cross-traffic. | ||||
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| Actual
implementation But the success of this alternative rests entirely on the geometry of the actual implementation. |
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| From
what I have read on this underpass so far, all traffic headed to
hebbal has to take this loop. Providing a nice little loop
for single
lane is fine, but for the entire throughfare on this road to take the
loop, the loop better be wide with a
nice and smooth curvature.
If the turn radius is too small or the bend too sharp, then this design
will seriously slow down north bound traffic. Hopefully the palike has
paid enough attention to it. Further, since actual turning on the loop happens on the underpass the question is, is the underpass long enough to ensure smooth u-turns? Also, is there enough space on sankey road to allow smooth u-turns? |
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| As is
the norm for palike, no details were avaialable on the its website. And
as is the norm for papers, no useful information was available in most
of their reports either. But a report I read in the Hindu, fleetingly
mentioned that the vehicles are to take the u-turn after travelling 50
meters on Sankey road. Based on that, I drew a rough approximation of a
possible design. The red rectangles are approximately of the same size
as the buses seen near the top right of the image. I dunno if the acual
palike design is similar to this, but this figure highlights the
challenges at Cauvery Junction. |
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| The
issue here is that deeper the loop goes into sankey road, away from
bellary road, more difficult the turn becomes. On the other hand, if
the loop is too close to the bellary road, then there will be no place
for underpass traffic to emerge. As you can see the loop is real tight
and traffic will have to slow down. That is OK as long as it keeps
moving. If the loop gets too tight, one alternative is to use this loop as a slip lane for north bound vehicles. When S2(see pic above) is green, they could make S1 and S3 red. Vehicles at S3 then have the option of taking the loop to avoid waiting for S2 to go red. When S2 is red, they just continue straight. That way, irrespective of the signal, vehicles at S3 always have an option to keep moving. Though all this switching could get messy and very confusing. |
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| The
palike will have to walk on a very tight rope to balance all this.
It will be very difficult to make all this work. And I have not even
said
anything about the width of the underpass to carry all traffic from
west headed to either north or south. |
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Going over Cauvery Junction Underpass
Back-of-the-envelope analysis and some rough sketches to understand the
cauvery junction underpass solution. Looks like the palike will need
more than the magic of precast boxes to make this work.
- tsubba ರವರ ಬ್ಲಾಗ್
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ಪ್ರತಿಕ್ರಿಯೆಗಳು
there is a right turn to
Unfortunately...
information access.
cauvery junction
Cauvery Junction
Lots more work to be done
info on the 5 underpasses
Ok, my bad...
what is the width of the underpass?
Underpass model
This is the picture of the model of one of the underpasses. DH labeled this as palace guttahalli. If it is the BDA jn u/p what is that big cylinder doing in the middle of the road? Though I am happy that there seem to be slip roads on both sides of the u/p. So how wide is the main throughfare going to be, 2x2?
ids can you look at the descriptions and see if it all makes sense?
t have not been able to figure out the widths. am looking for it myself. so what happenned at cant?
BDA junction
drainage
According to deccan herald,
dimensions
I'm not confident
Also...
underpass pic.
Went over the underpass today
Oh and...
cauvery junction
A vague idea that led to ‘magic box’
Cauvery Junction Inaugurated
(Pic source: ToI)
Design Implications
The design of the underpass reduced the speed of the vehicles to as low as 10 kmph (some time dead slow) before taking a U-turn above the underpass surface. But it has reduced the travelling time by at least 60 per cent between Mehkri Circle and BDA junction. Earlier, vehicle users were required to wait for nearly 3 to 5 minutes at Cauvery junction signal. With the construction of the underpass, vehicles will not stop at the junction although their speed gets reduced. BBMP Commissioner S. Subramanya said that it would take a week for people to get used to the U-turn, which was the only possible solution in shortest time.
Though the underpass has eliminated signal lights at the Cauvery theatre junction, a fresh manned signal has emerged in the middle of Cauvery theatre-BDA junction stretch. The manned junction has been necessitated to facilitate the Vyalikaval-bound vehicles from Mekhri Circle take a U-turn well before the BDA junction. However, Dr S Subramanya said the problem would be over once the construction of the underpass at BDA junction is completed. (DH)
He said: “The outcome of the Cauvery junction underpass will be evident only after both the BDA circle and Windsor Manor junction underpasses are ready. “It took 20 minutes on Wednesday to travel from Mekhri Circle to BDA Circle. Once the works at this junction begins, commuters will be inconvenienced and further delayed on this stretch. The impact of all three underpasses can be assessed only after they are complete,’’ he added. (ToI)
Problems with Pedestrian CrossingHowever, absence of pedestrian crossings has become a worrying factor for those who work in the nearby business establishments as they have to risk their life for crossing the roads. He said the BBMP would consider building a skywalk for pedestrians at the junction. The government had plans to start an elevated train service to the airport from the City. “The Palike will go through the alignment prepared for the elevated train and decide where to put the skywalks,” he said. (DH)
Cracks within 72 hours...
(pic source DH)
Roads at the underpass were asphalted only two days before the inauguration. But they developed cracks within a few minutes after vehicles started plying. The commissioner said roads developed cracks at some points where the land was dug to shift utilities. The Palike has identified such points and repair work will be taken up soon. (DH
Alternative (ToI)
DelaysWhile the debate over the feasibility of the project continues, the BBMP officials clarified it was a better option than the conventional underpass, which would have required shifting of utility lines. “BWSSB authorities demanded Rs 30 crore to shift utilities at three junctions — Windsor Manor, BDA and Cauvery theatre. The cost of three magic boxes is Rs 7.5 crore, which is a third of the utility-shifting cost,’’ they said. The BBMP has vowed to complete the magic boxes from High Grounds police station to the Hebbal flyover before the first flight takes off from the new international airport.
Construction of the underpass began on January 15 with the Palike declaring the work would be completed in 72 hours (three days). As a BWSSB water pipeline got ruptured during excavation, the work was delayed forcing the commissioner to seek 10 more days.
The second deadline too was not kept as the seepage of water continued. A horizontal borewell was then sunk through which the seepage water was led into a nearby storm water drain. The work gathered pace once the problem was solved. (DH)
Public Reaction
The new underpass evoked fairly good response among the vehicle users with a majority of them expressing satisfaction over palike’s attempt to ease traffic congestion on Bellary Road.
Although BBMP failed to complete the work in 72-hours as announced earlier, people said that finishing a project in 35 days, that too with a low cost of Rs. 1.5 crore, was an achievement by a government agency. (The Hindu)
“I have been visiting the site for the last 34 days. Often, I felt there could have a simpler solution. But with time, I began to appreciate their efforts. The junction is now signal-free. They need to be careful with their next project as utility lines are all below the road. Another aspect they need to look into is pedestrian crossings,’’ said 75-year-old K N Visveswariah, retired joint director (agriculture) and resident of Lower Palace Orchards. (ToI)
Traffic cops hailed the project. But they also rued the lack of regulation of private vehicles. “Projects like this one provide a breather to us. But how long will you go on adding infrastructure? We should freeze the new registrations for some time and encourage public transport,’’ said a traffic cop on duty. (ToI)
Human Interest (ToI)
When the magic box underpass at Cauvery junction on T Chowdaiah Road was thrown open to traffic on Wednesday evening, it created quite a buzz. Bikers and car drivers could not wait to drive through the ‘box’ to figure out what it was all about.
The BBMP decided on a quiet, informal inauguration, but that could not prevent a carnival-like atmosphere. While peakhour traffic was caught unawares, but that did not deter them from waving at the crowds, the BBMP and police personnel. Pillion riders whistled and clapped as they drove through the magic box. Motorists were quick to observe the new signages directed towards Bellary Road and MG Road at the mouth of the underpass.
Initially billed as a three-day project, it took all of 34 days to be completed. The eager anticipation of Bangaloreans began to turn into exasperation. But on Wednesday evening, everyone — curious onlookers, residents of nearby localities and senior citizens gathered around the site during the inauguration — agreed it was worth the wait and trouble.
On to BDA Junction
The work on “magic box” underpasses at Windsor Manor and BDA junction would commence after February 22 depending on the strike by trucks and other transport vehicles as transporting construction material had to be ensured before beginning the work, he added.
Deccan Herald Will it ease traffic or not?, Underpass is thrown open, finally
The Hindu BBMP opens its first ‘magic box’
ToI Experience The Magic Feb 21,2008
Cauvery Junction Possible Lane Markings
what if?
curves
like your parent post..
this could have avoided the u turn and instead made it a wider parabola...
however the ground realities could be all together different..I havent seen the place yet!
pics
CJ girder failure
Finally time to bid Farewell for this Magic
The city police are all set to close the ‘magic box’ underpass at Cauvery Junction for a few months to felicitate the smooth flow of vehicles heading to Kempegowda International airport (KIA). The magic box will be reopened once the proposed steel flyover from Basaveshwara Circle to Hebbal is commissioned. City Police Commissioner N S Megharik will issue an order regularising the closure once a decision is taken in this regard, said the police.
“The traffic cops wanted to analyse the situation on Monday due to the closure. The police have identified diversions. The closure of the magic box did not cause much inconvenience to the road users from Bhashyam Circle end. The police inspected the situation at the junction in the morning and evening. The situation was more or less normal,” Additional Commissioner of Police (Traffic) R Hithendra told Deccan Herald.
The police said that the magic box was set up in a wrong place which led to blocks and congestions on the stretch between Mekhri Circle and the Windsor Manor bridge. “We will reopen the magic box only after the elevated flyover is thrown open for road users,’’ Hithendra clarified.
http://www.deccanherald.c...
all magic needs dismantling
I would say all the magic bridges need to be removed on the airport road..
BDA jn/Cauvery/RT ngr/Anand ngr etc..all of them..they are the most unscientific contraptions..
However, this does not mean that a 6 lane steel bridge is the replacement needed..there is a lot of planning needed to manage traffic on this road and engineering is one of the sollution..
For example, the hebbal bridge is only 2 lane wide and how can we expect a 5 lane (3 from bridge + 2 below) merge into this 2 lane?
Way too many questions...and engineering does not have all the answers!