'Pre-Cast' Solution - Koramangala 100Ft Rd
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Written By Naveen - 6 December, 2007
Traffic
Bangalore
Koramangala
magic boxes
Now that solutions to traffic conflicts may be possible with underpasses using pre-cast arches, & after watching the Koramangala 100-ft rd video, I tried to see if I could find solution/s for the stretch from Sarjapur rd to 80 ft rd.
The problem is obviously that mainstream traffic on 100 ft road is interrupted & conflicts with local traffic moving from the western to the eastern sides of the road & vice-versa. Also, some of the mainstream traffic turns & moves to the east or west. So, this also needs to be addressed.
The situation is further complicated with limited spacing between these deviations. In less than a half km of the road stretch, there are two main roads that join on each side of the road.
Fortunately, there are no '+' junctions with traffic from four directions converging to the same point with different destinations, such as those at 100ft rd - Sarjapur rd junction, or 100ft rd - 80ft road junctions at the extremities on this stretch.
The traffic flow directions on the two one-way roads on the western side will need to be reversed & also, the two roads on the eastern side will have to become one ways. Since all these 'T' junctions are too close to one another, vehicle speeds will have to be restricted with speed breakers as lane conflicts are bound to occur (see image) within short distances.
Other possibilities were explored, such as changing the one-way directions, etc. but this resulted in the underpasses overlapping or insufficient room for underpass ramps due to space limitations.
One thing though, I'm not sure if single lane underpasses can be used by buses - some of these roads joining the 100ft rd are also bus routes.
naveen,
since it is a 'city road', wanted to see how a signal based solution would work.
here are 4 scenarios. i figured that the distance is about 0.5 kms. but have to figure out timings.
this is a very conservative scheme- all three lights in a direction go on and off together. and guarantees no conflict. but will prolly have long waiting times at the signals. you can prolly tweak some more performance by switching each of the lights in a given direction individually. but then it conflict is possible. perhaps need to trade that off.
Scenario 1
Scenario 2
Scenario 3
Scenario 4
Hi TS,
I was describing underpasses similar to those that are going to be installed on Bellary road - precast ones which are below road level that can be fitted quickly, & not 'flyovers' like the ones you mentioned, which take a long time to be built. The road will have no structures above it, just a barrier to separate the entry & exit ramps/lanes into & out of these underpasses (similar to Mekhri circle underpass, but of smaller width/height).
Although there are no signals at these intersections at present, there are cops stationed there during peak hours but they are not able to manage the situation as mainstream traffic (on the 100 ft rd) is enormous & piles up quickly when flow is stopped to allow traffic flow from any one of these other roads to proceeed (viz. 1st/main or 5th/cross on western side; or 7th cross or 8th main on the eastern side).
The conventional signals that you marked will work for low volumes & when there are no major pile ups. The situation now is well beyond that as volumes are already too high to manage with signalisation (or traffic cops).
What is pressing here is the need to prevent traffic pile ups on 100 ft rd. This is of primary importance since if flow is stopped, you would have 'signal to signal' choke up of traffic (from sarjapur road almost right up to 80 ft rd) - this is occuring quite frequently now during peak hours.
At the same time, provision must be made for traffic from the roads on eastern side of 100ft road to proceed to the western ones & vice-versa (say from 1st main to 7th cross; or from 8th main to 5th cross). Such 'local' traffic will only be using a short length of 100 ft rd.
There may also be some traffic that may come from these roads & join the mainstream traffic & continue to proceed along 100 ft road to other destinations & will not turn.
Finally, there may be some traffic that may have have arrived with the mainstream but wants to turn to east or west.
To allow for all possibilities, if four underpasses are fitted as marked, traffic on 100 ft rd can flow uninterrupted or turn east or west, & traffic from these other roads can also move to their desired destinations (join mainstream headed north or south; or come from west & proceed to the east or viceversa) without interruptions.
Trust this is clear ?
thanks for clarification.
one question briefly, can you think about it terms of lanes.
also will it be possible to avoid east to west & west-east traffic on the main road? can we avoid right turns from east & west sides?
have some inputs will get back.
Hi TS,
About lanes - you are right. Lane conflicts can be minimized if all underpass entry /exits are to the left rather than in the middle. I have modified the sketch (also, made it clearer) & wanted to attach with this, but there seem to be no options. Any ideas ? Can I replace the first sketch I posted with the new one ? Too many sketches would confuse anyone reading !!
Blocking off the divider opening at 8th/Main had been tried earlier (about two years ago) but there were protests & it had to be reopened.
Traffic from east to west & vice-versa cannot be shut-off as there are residences & commercial establishments on both sides.
Say, someone on the east wants to go to forum mall, he will have to cross the 100 ft rd & go. If this were made unavailable, then he would have to go to hosur road & then proceed, which makes it very roundabout.
Similarly, if someone from the west wants to go to Wipro Campus on Sarjapur rd, then he will have to go to hosur road (on 80ft rd, near forum mall) & then turn into sarjapur rd at madivala checkpost, which is again very roundabout.
For the same reasons, right turns on 100 ft rd from east & west sides cannot be shut-off.
Since this arrangement with underpasses will provide a free run from 80ft rd to sarjapur rd (& vice-versa) for thro' traffic, the road stretch will become streamlined. There will be pile up at the extremities, though (80 ft rd & sarjapur rd junctions) due to 4-way junction signal delays. On airport road flyover, you hardly see any traffic on the right turn loop ramps. This is because flow is uniterrupted & vehicles arriving are discharged speedily. Similarly, the underpasses should serve well here.
hi naveen,
when you say underpass, i think you mean the main thrufare will remain at the level it is but the loops across the main thrufare will be over the road right? not clear.
thanks.
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