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Poor design of flyovers lead us nowhere in solving traffic problems

ಮೇಲೆ
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Infrastructure

 All over Bangalore, there is a galore of small small flyovers and now underpasses. But, none of them are constructed with thorough thought process and planning behind it. Usual mode of construction of flyover is to have 4 exit ramps and 4 entry ramps in semicircles like we have seen in foreign countries as well as in our NICE Somapura road junction. It eliminates junction waits in all four directions in all possible 12 combinations.

Domlur Flyover

Domlur Flyover... 

In Bangalore, we have our own ways of construction such as one underpass and one flyover crossing in a + just addressing the straight moving traffic and not the turning traffic which serves 4 combinations. Good examples are the Dairy Circle, Jayadeva Flyover or sometimes flyover just addresses the  only one straight moving traffic or 2 combinations like the Silkboard flyover which servess only the Hosur Road and not the Ring Road. 

In a junction, there are 12 possible routes. Our flyovers or underpasses usually serve 2 -  4 possible routes only. Very rarely such as Domlur flyover which can address most of the combinations.Because of this poor design, irrespective of number of underpasses or flyovers, blockage continues to prevail in the junctions.

But, all 12 combination needs more space at the corners of bottleneck junction which is difficult to acquire in Bangalore.

Atleast, wherever possible, it could have been constructed to address maximum combinations, but it was not done. Example is Silkboard flyover, where plenty of space is available at the corners, but there is no ramp and serves only 2 combinations.

 

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blrsri's picture

silkboard solution

ಮೇಲೆ
105 users have liked.

very true that the junctions are the culprits for jams everywhere..

btw to solve the silkboard deadlock, which will  get worse with the elevated highway being commissioned, we can have a bridge over the existing bridge..like how the Nice road and the BETL meet on hosur road..

this should solve the silkboard maha jam!

Vasanth's picture

Jayadeva - Silkboard on ORR, always slow moving

ಮೇಲೆ
96 users have liked.

 Jayadeva to Silkboard, there is always slow moving traffic. Traffic signal in BTM junction leads to long jams same is the case in Devegowda Petrol Bunk. Long wait signals always causes delays, frustation builds and people try to release all their conserved energy during the wait once the signal turns Green.

Synchoronized signals is another necessity to remove the frustation and rushing. Something like an average travel at 40kph should lead to all signals showing green.

 

Here is an example of synchronized signal in Denver.

 

 

blrpraj's picture

full cloverleaf to be avoided if possible

ಮೇಲೆ
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The full cloverleaf interchange shown in the very first photo looks good from the air but is an outdated interchange design that is prone to accidents and traffic jams caused by weaving traffic. This design was essentially used to provide connectivity in all 4 directions between 2 different roads at a lower cost with minimum concrete. Also, one should not forget that land is a premium & a full clover leaf occupies more land than a multilevel stacked interchange.

 I am not sure if that is the way to go for future interchanges in and around Bangallore. Just my 2 paise..experts please add if you have more knowledge; but yes, I concur with the author of the thread that more thought needs to be given to the design and implementation of flyovers.

tsubba's picture

blrprj

ಮೇಲೆ
115 users have liked.

(Full cloverleaf) is an outdated interchange design that is prone to accidents and traffic jams caused by weaving traffic.

why do you say the above? can you explain. alternates? thanks

 

 

blrpraj's picture

@t.subbabhatta

ಮೇಲೆ
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"why do you say the above? can you explain. alternates? thanks"

I say it precisely because of the "weaving" traffic that I mentioned. Having driven through one such interchange before, during and after reconfiguration I could see a noticeable difference (before ..when the interchange was a full cloverleaf and after..when it was reconfigured to a partial cloverleaf). The interchange I am talking about is the I-405 and SR 167 interchange in Renton, WA of US near Seattle.

Well, the alternates are to provide directe connections via flyovers. Such reconfigurations of full cloverleafs are going on in quite a few places in the US wherever possible. I had to google around quite a bit to come accross an article that explains the issue that I was referring to; this perhaps should explain clearly the flaws of a full cloverleaf and why the experts are getting away from it and what the alternatives could be -

http://www.wsdot.wa.gov/NR/rdonlyres/C35F706B-4462-4DA3-9C64-DA27681E78EF/0/i5TriangleFolio_Summer2009WEB.pdf

Please note that I am not saying a full cloverleaf is bad because the US says so. Just driving through one made me question the design of the interchange (why was it designed in such a crazy way)..further analysis and digging around in libraries and a chat with civil engineers revealed that a full cloverleaf was the cheapest (and state of the art) way of providing full connecivity in all directions between 2 intersecting high speed roadways in those days (60s and before) when traffic was relatively low; not any more though with todays traffic volumes. Now, it does not of course mean that the traffic jams will disappear in a reconfigured interchange..it is just that the cloverleaf is the least efficient of interchanges for getting the job done.

To me it seems like our planners are going for the lowest cost solution by adopting outdated full cloverleafs.

pravn1984's picture

Why not underpass like.Dairy circle.

ಮೇಲೆ
111 users have liked.

 Interesting discussion abt clover leaf vs flyover. However, why not a underpass at silkboard junction. Would it impact the pillars of flyovers?. And, what will be the cost difference between flyover over flyover with underpass.

Vasanth's picture

Alternative looks way too complicated

ಮೇಲೆ
97 users have liked.

Alternative to cover leaf interchange looks way too complicated to understand itself and may be difficult to implement in Indian scenarios.

A good example is the Domlur flyover, which is without the coverleaf interchange, but provides many combinations. Our authorities has to wake up and consider the right design without blindly signing on the design whatever provided by the consultant and make such a huge investment a mere waste.

n's picture

Junctions and interchanges

ಮೇಲೆ
97 users have liked.

Junctions (broad), interchanges (type of junction) and cloverleaf interchanges.


blrsri's picture

space..space

ಮೇಲೆ
107 users have liked.

 Vasanth's Clover and Blrpraj's flyover interchanges take up lot of space and its difficult in the city to get something like this??

Btw the Washington's redesigned full clover still has half clover left in the design..! Also the redesign depends on flyovers..which are more expensive than Clovers!!

Weaving and all that need not be worried about cos, as we have in the domlur flyover, the traffic slows down on the exits of the ramps as there are traffic signals at the end of each!..

and where is the point of weaving..we assure smooth ride not limitless speed! ;)

At best what can be thought of is having half clovers kind of designs within city to save on space and increase optimization! 

 

Vasanth's picture

Project : Redesign of Silkboard Flyover

ಮೇಲೆ
95 users have liked.

 New Project : Redesign of Silkboard Flyover like Domlur Flyover. There may be many comments about its design, but it looks to fit without much space at the corners like a cover leaf interchange.

We cannot have underpass here because of various drains that are passing at the Silkboard junction which everyone can smell while passing by!.

We need to have two ramps on the ORR. On the Eastern Side (Marahtalli/HSR Side) , because of the availability of space, may be we can consider coverleaf style ramps.  On the western side, (BTM side), we need loops which doesn't occupy space.

Vasanth's picture

Pictures of proposed

ಮೇಲೆ
108 users have liked.

Silkboard Existing

 

 

Silkboard Existing

Silkboard Proposed:

 

Silkboard Proposed

pravn1984's picture

Another Design

ಮೇಲೆ
101 users have liked.

@Vasanth

In the design that you are proposing, the issue would be land acquisition in silkboard(Hosur Road- electronic city side) .

So, i propose an alternate design(slighltly outlandish, i might add).

Rationale of this design:

Vacant Land on the Hosur Road goplan side/Madivala side is govt land AFAIK.So, the idea is to maximum use of this land.

Current Junction: 

 Proposed Redesign:

Redesign steps are as below:

  • The current Hosur road from madivala side will not hit the flyover directly but go on a loop where the traffic from ORR-BTM will merge. ( So one right turn taken care of).Finally with a new ramp it will hit the existing flyover.
  • A clover leaf kind of loop will be provided for the ORR-BTM traffic to merge with Hosur road-madivala traffic.
  • Traffic from Hosur road -EC side to ORR HSR side will be through a new ramp which joins a new road in the govt land.( parallel to the existing road).(Another right turn).This will cater now both for the traffic from madivala and EC side which wants to move to ORR.
  • An up ramp from ORR HSR side to the existing hosur road(direction reversed) which will be used to do one more right turn.
  • A traditional clover leaf to do the right from Hosur road madivala to ORR-BTM.

 Advantages:

  • Optimum use of the govt land
  • Further, toll /bus bay options can be integerated in the govt land.maybe even a transit center.
  • When redesign is happening, there will be minimum hindrance to the existing traffic.

 

Ps: The above and this post can be moved to silboard re-design thread by  admins.

Vasanth's picture

@pravn1984 - Silkboard Redesign

ಮೇಲೆ
118 users have liked.

 Pravn,

Thanks for the nice drawings.  I daily pass through Silkboard junction and I have observed that there is ample of space in the silkboard compound which would be sufficient to host two ramps. That would avoid the U turn of ORR. 

Your design will save lot of construction work and down time. But our traffic is bit unpredictable and don't know how it may behave here. 

Just like KR Puram additional ramp design project, we need to start on this.

Also, Jayadeva to Silkboard which takes hefty half hour to cross via BTM needs to be addressed by Synchronized signals and reducing the signal wait time.

What I have personally seen is in the CBD, like JC Road, traffic moves so smoothly although volume is there. There is not much of wait in the signals whereas the ORR is not addressed in similar fashion, especially Devegowda Petrol Bunk and BTM areas - May be local police not acting properly? 

 

 

Vasanth's picture

Domlur flyover - Benchmark should be followed in other places

ಮೇಲೆ
100 users have liked.

 I had passed on Domlur flyover mostly in bus or car and had not closely observed, this week when I passed through by 2 wheeler during day time, I could cleanly observe the design. Basically, only one side of the flyover, indiranagar side, there was land available. One corner was occupied by Diamond District, other corner by some worker quarters.

Same can be replicated in other important flyovers.

One that immediately comes to my mind is National college circle flyover which is currently useless and we have a signal beneath it. There is one always empty petrol bunk and another park which could be used to construct extra loops. Northern side we have the Metro coming which is finding hard to pierce due to this unwanted poorly designed flyover

Silkboard is another candidate which needs immediate attention. Construction of these loops doesn't affect traffic much since it is at the corners and not much on the centre.

Diary Circle and Jayadeva has little space to construct loops. I still cannot understand why there is a signal under Anand Rao Circle flyover.

Another redesign thread going on KR Puram flyover redesign.

We need space atleast in two  empty corners for construcion of loops for addressing all 12 combinations while constructing new flyovers.  

idontspam's picture

Productive destruction

ಮೇಲೆ
120 users have liked.

 One that immediately comes to my mind is National college circle flyover which is currently useless

Dismantle it... Better than trying to fix it by building more. It wasnt even on a corridor.

idontspam's picture

Not a design solution...

ಮೇಲೆ
96 users have liked.

...But, there is a very efficient practice of making protected/permissive combo turn lanes with vehicle actuated signals that should be tried out first. 

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