'Pre-Cast' Solution - Koramangala 100Ft Rd

6 December 2007 - 9:55pm — Naveen

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.

Comments

underpass

tsubba - 6 Dec 2007 - 9:23pm

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.

signals?

tsubba - 7 Dec 2007 - 1:27am

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

Underpasses - KML 100Ft Rd

Naveen - 7 Dec 2007 - 6:49pm

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 ?

K'mangala

tsubba - 7 Dec 2007 - 10:14pm

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.

PreCast Underpasses - KML 100 Ft Rd

Naveen - 8 Dec 2007 - 5:51pm

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.

naveen...

tsubba - 8 Dec 2007 - 6:03pm

flickr is the best method. then make sure sure you select the right option from input format use filtered html if you use flickrid or select full html if you use html tags

KML 100 Ft Rd - Sketch for Underpasses (Modified)

Naveen - 8 Dec 2007 - 6:41pm

Pls click to see a modified sketch : http://flickr.com/photos/...

KML 100 Ft

tsubba - 8 Dec 2007 - 9:06pm

naveen, a view of how lanes might work.

there is a white space behind an underpass. that is road space that cannot be used. because of that some interesting things happen. for traffic going to 80 ft road, in this direction there will be 3 effective lanes. 2 main and one 1 "turning". the left most lane between the two underpasses will become a lane dedicated to turning/collecting(for traffic from 1st cross). which can help merging. for traffic from 80 ft road: in this direction there will be only 2 effective lanes in the area between the two U/P. (this the area to the left of canara bank in the image.) could it be reused as parking? in total not a bad proposition at all i think. one more thing, are there any solid reasons why 1main and 5 cross are oneways in those direction? will they ever reverse the oneways?

KML !00 Ft Rd - Lane System

Naveen - 8 Dec 2007 - 11:36pm

TS - I see what you meant when you mentioned lanes now. This road has only 2 lanes either way (it's presently a 4-lane road). It is only after the 80 ft rd (towards Indiranagar) that it becomes 6-lane. The lanes plan will be okay if the road had 6 or more lanes (3 or more each way). On this stretch of the road, planning lanes may be really difficult as one lane would be taken up by the underpasses. Thus, only one lane would remain & will be required by almost all other traffic (mainstream /local /turning, etc). In fact, in practicality, if this were to be built, they will take away some of the sidewalk & leave about one & a half lanes (a car & a bus may manage together) just where ramps are positioned on 100 ft rd. On the other roads also, they may take some of the sidewalk & similarly leave about 1.5 lanes (they are two-lane roads). 1st main & 5th cross are presently one-ways not as shown in the sketch but opposite (i.e. 1st main takes traffic away & 5th cross brings them to 100 ft rd). Also, 7th cross & 8th main are two way roads presently. This is why there is so much chaos on that road. In any scenario for resolving this, it is obvious that all those four roads will have to become one-ways since the divider on 100 ft rd would need to be continuous. Thus, four possibilities emerge : 1) 1st main towards, 5th cross away, 7th cross towards, 8th main away 2) 1st main away, 5th cross towards, 7th cross towards, 8th main away 3) 1st main towards, 5th cross away, 7th cross away, 8th main towards (this is the one chosen as it works best & is the one on the sketch) 4) 1st main away, 5th cross towards, 7th cross away, 8th main towards Only case (3) works - the other three cases have various difficulties. Either they do not meet all conditions required or there is not enough space for ramps. In one case, the ramps face & oppose each other, though on opposite sides of the road, but the road /structure might become weak. Hence, I applied case-3.

KML 100 ft

tsubba - 9 Dec 2007 - 8:42pm

N, have seen your post. interesting. will get back.

TS & Others

Naveen - 10 Dec 2007 - 5:23pm

I am proceeding overseas on job travels AM/12th & wl be back after a few months. Meanwhile, I will try to keep in touch wherever I am, but it may be infrequent. I enjoy being a part of Praja & look forward to be back soon.

travel

tsubba - 10 Dec 2007 - 6:04pm

good luck naveen with your travels. :) bring some goodies.

Goodies - Ha !

Naveen - 11 Dec 2007 - 9:25am

TS - many thanks. Goodies ! My family also joins you in asking for the same !! SB was mentioning about a meeting, no news about it after that. I hope such a meeting takes place when I'm back here as I look forward to meet you guys.

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