Hi Sanjay,

Thanks for your feedback. I certainly may have missed certain traffic streams since I had just picturised it in my mind. I have created a rough sketch of the lanes to get a clearer idea, which is shown below. Please click on the image to get a bigger version. It is hosted in Flickr. I have omitted the curve in the road to make it simpler.
I created the picture using the drwaning tool in Microsoft word since I didn't have a better tool available. It isn't great, but should convey the general idea of the traffic flow.



This is a rough sketch and not to scale, since I don't have access to the detailed plans. I have shown only two lanes on the service roads. However it is possible that between the two signals, it is possible to have an extra lane under the flyover, provided the flyover is high enough.

Since the Agara junction has survived all these days with only a traffic island and without signals, it could probably survive in future also without signals. The whole middle section under the flyover from 24^th main to 27^th main can be treated as one big traffic island. However the bus lanes in the middle will complicate things and signals are required for safety reasons and also to provide priority to buses.

The signals at 24^th main and 27^th main certainly needs to be synchronized. To reduce the cycle time at the 24^th main signal, the traffic coming from Koramangala and wanting to go to Silkboard or 24^th main, can be forced to come to the junction of 27^th main and make a U-turn. Anyway the amount of traffic from that direction is low. Also traffic coming from HSR 27^th Main and wanting to go towards Iblur can be forced to go to the 24^th main signal and make a U-turn. (It is sort of like that even now; there is a sign installed at that junction to that effect, however most people ignore the sign and just take a right turn at 27^th main.)

I also observed that the service road in front of Sobha apartments at the 27^th main junction needs to be made a two way street. That is the only way the Sobha residents will be able to get into the ORR towards Silkboard. There are also a few shops on that service road and they need to be provided a way to go towards Silkboard.

Come to think of it, the same situation will apply to the residents of the service road near 24^th main, adjacent to the temple, if they need to go towards Iblur. But those people can at least go towards Silkboard, get into HSR layout and come out through 24 main or 27 main.

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Guidelines for Horizontal Curves -IRC: 38-1989

My own formulae:

1.0 The IRC restricts the superelevation to 5.0%

but is silent on the speed.

e.g. if the superelevation required for 60kms /hrs is 10.0% than

it can be done upto 5.0% practically, IRC does not laydown guidelines

for the speed to reduce or increase.

2.0 Also providing the max allowable superelevation may have 

adverse effetcs on the bearings of the bridge superstructure.

This was just a first impression,

there are various remedial measure one is speed

other is extra widening, not allowing slow moving vehicles etc..

 

nJ

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Iblur Intersection

It is now clear that a single 3-lane ramp is going to be positioned here for vehilces arriving from Maratahalli & proceeding towards Silkboard to jump over the intersection without any conflicts. A service road on the left of the ramp allows those vehicles that would want to turn to Sarjapur.

The other direction of travel along ORR does not conflict with any other flow & does not need an elevated ramp. Therefore, it has been retained on the surface.

Only one traffic conflict will remain - vehicles arriving on ORR (from Silkboard) & proceeding towards Sarjapur will conflict with those that arrive from Sarjapur & want to turn to ORR towards Marathalli. This can be regulated easily with traffic signals, which should include a phase for pedestrian crossing.

The need for a roundabout will not be necessary as traffic conflicts are too few.

Agara Intersection

The two ramps allow uniterrupted flows along ORR, thus removing bulk of the traffic, whilst left service roads take care of traffic joining or leaving ORR to & from Koramangala. A traffic signal would become essential to regulate conflicts below the ramps (eg. traffic from Koramangala turning into ORR towards Silboard conflicting with those that arrive from Iblur & proceeding towards Koramangala, bus movements at surface, etc.).

The median surface bus lanes is a good option provided pedestrian access is included in the signal phases & traffic calming measures are in place (speed breakers, signage, etc).

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The bridge plans are good..what about pedestrians and the traffic planning below the flyover?

As we understand there are too many projects which have been built in bangalore with peds no where in the plan and traffic below the flyovers is always a mess and we live with the incomplete planning for years!

Lets see/make a more comprehensive plan for this!

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Arent pedestrain facilities like sidewalks and zebra crossings important enough to be a part of an engineering drawing???

Why arent they considering marking a cycle track when they are planning. It hardly needs 2 feet in a corner on both sides. They could use the cycle track as the BRTS lane seperator.

On signalling here is an example of seperate phases for Cycle, Bus and Vehicles that may be appropriate for Iblur jn 

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The following are my observations and comments about Iblur junction

A image showing the bridge location on a google earth view can be seen at link below.

http://picasaweb.google.com/lh/photo/rize8Td9Z8nCbcvP3exmaA?feat=directlink

Approaching from Marathalli side

Private automobile

• Going towards Silkboard is easy - the carriage way will probably be about 3.3m wide per lane which is very comfortable in the curve. 3.3 meters works out to about 10.8 feet. 
• To turn towards Sarjapur, there is a broad turn lane provided in which our drivers will fit two lanes of traffic. The turn is a rather sharp one. A necessary check is to see if the proposed turning will be smooth for a large bus or tractor trailer.
• To do a U turn or go into the service road towards the Shobha and Sun City apartments will be comfortably possible. Hopefully, three lanes will be marked out there with (a) One lane for right turn/U Turn after pillar 9. (there will be a few folks who will probably access the road after the ramp comes who will want to turn right. (b) One lane to go straight or turn left and (c) another lane only for a left turn.

 

Approaching in a bus along the BRTS lane

• The bus going on towards silkboard will be able to go along the BRTS lane, but will have to wait at a signal. The lane itself is 3.5 meters (11.5 feet) wide. I am not sure if that is enough for one bus to overtake another at the stop.
• A bus turning left to Sarjapur road is going to have some challenges. The drawing does not clearly mark this information. The bus will have to turn between pillars 8 and 9. My rough estimate is a 70 odd feet gap between the pillars and the flyover will be near its highest point of 25 feet vertical clearance. So it should be comfortable. I am disappointed to not see this path marked in the map.

Approaching from Sarjapur side

Private automobile

• Going towards silkboard is fairly easy. There is almost a 20 foot wide service lane. Will that be one lane or two lanes? There is a decision to be made as to whether one lane should be a dedicated always green lane and then the other lane regulated by signal.
• Right turn towards Marthalli or into the service lane should be easy to do, but regulated by signal.

 

Bus

• A bus would turn right between pillars 9 and 10 into the BRTS lane and go straight into the silkboard bound BRTS lane between pillars 10 and 11.
• Lane regulation from this approach will be important to help people select the right lane to turn into the service lane, and main lanes towards Marathalli

Approaching from Silkboard 

• There are four lanes shown in the drawing apart from the BRTS lane.   There should be some good lane management and discipline followed here. The rightmost two lanes should be reserved for going straight and the left two lanes for going left. A traffic island and some geometry change could help enforce some discipline.

Sun City and Sobha

For the residents staying in Sun City and Sobha. How do these guys enter towards Silkboard or Sarjapur? Is there an option to design a fourth direction of entry into the signal? We know that people will try tricks here because otherwise they would have to drive an extra kilometer or so.

With the BRTS lanes, I am not sure what happens to the U-Turn on the ring road? Maybe right now, the BRTS is not implemented all the way in the ring road. However, if the expectation is that drivers will go all the way to Bellandur before doing a U-turn, that may be a bit excessive. It is important for BDA to think of solution which is consistent with their design philosophy for the BRTS lanes.

Access to the shopping areas on the left hand side of the approach from Silkboard. 

It might make a lot of sense to modify the 4 lane approach to provide a service lane to the built up area on the left.

Developing some of the back roads will also help those area to have some option with regards to exit. This needs more thought and expansion

Road geometry beyond the bridge

There is no details in these drawings on how this bridge area integrates into the existing roads and traffic flow. Maybe there is a plan to upgrade and improve the ring road all along, but the questions right now are as follows (a) How will this grade separator merge with existing traffic flow?

BRTS 

The BRTS lanes are a big mystery. Are these going to run all along the ring road. Has this feature been put in solely for JNURM funding? There is a requirement for some major redesign all along the ring road if BRTS is implemented. Has that been thought through?

How will pedestrians access the bus stops? Crossing is going to be a nightmare, especially for those coming/going to the sun city side. The size of the platforms provided itself is reasonable.

Will all types of busses run along the BRTS or will it be some particualr type of service. Running a volvo and an ordinary bus along the same lane is a terrible idea because of the acceleration difference.

Pedestrians

There is really not much consideration for pedestrians on these roads. There are plenty of residential areas around the junctions and it is fair to expect a reasonable and growing number of pedestrians. If you do not make it easy for people to walk and cross the road, they are not going to take the bus.

Approaching from the Silkboard side, people only have a one meter (3.3 feet which is roughly one and a half vitrified flooring tiles) drain cover to walk on. Looking at the rest of the ring road, there is a good chance the drain covers will never be put in place.

Negotiating the curve from silkboard to marathalli, a pedestrian will have to cross a yawning chasm with no well defined pathway for him/her. Something like that is easy to address at the design stage.

Planning for pedestrians is urgently necessary.

With some small adjustments to bridge and roadway dimensions and tucking a little bit of the roadway below the bridge, by the side of the pillars, it will be easily possible to accommodate pedestrian sidewalks better.

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1.0 The flyover with two curves should not have vehicles

running more than 50kms /hrs.

2.0 The flyover with one curve cannot have

vehicles running more than 35 to 40 km/hrs.

This speed is based on the design of the curves as seen

on the drawings.

nJ

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Thanks for the info Nitin.  Can you cite a source of the speed numbers please?  I mean, is this information available in a manual or handbook etc.  Thanks.

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IDS,

The ideas you have highlighted and captured in the form of photographs are good ones that have been tried and tested abroad and they work in societies where following a rule/following a laid down system is the norm rather than the exception, it is inbuilt in their culture and they cannot function in any other manner even if they want to (their society will simply fall apart without rules or a system..they simply cannot function).

India is a different story all together where we seem to thrive under chaos. We would need nothing short of physical concrete barriers and an army of policemen/traffic marshals to keep cyclces, buses and other traffic in their respective lanes. Multiple signals for different types of traffic would lead to absolute mayhem and the usual "confusion".  Not being pessimistic about your ideas....just being a realist as to what can be achieved. We would need a full generation of school level education and basic reforms at youngest level before people make it a habit  of following rules and signs as a norm rather than an exception (i don't know if we would live to see that day), having said that the immediate solution would be to have physical barriers.

 

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Agara junction will be a three lane elevated path for through traffic on the ring road. That part is relatively straightforward. Coming from Jakkasandra /Koramangala and merging on to the ring road is also quite simple. The drawing appears to show a platform at the merging point which will choke flow. That is a bit disturbing.

[gmap markers=letters::12.91890657418042,77.63214111328125 + 12.91890657418042,77.59918212890625 + 12.896150535950834,77.640380859375 + 12.919575838058406,77.64724731445312 + 12.916564136486734,77.65308380126953 + 12.92409332232521,77.64947891235351 + 12.922754816987996,77.64827728271484 |zoom=15 |center=12.92605923903012,77.6462173461914 |width=500px |height=400px |control=Small |type=Map]
 

The concerns are the following:

There is no provision for bus stops shown on the BRTS lanes. Pedestrians are going to have to cross the road and need a safe area to wait for the buses. Planning the location is advance is critical. 

There is no provision (if you do not count a 1 meter wide drain cover) for pedestrians. There are plenty of pedestrians in this section of the road. A major layout abuts this intersection. Anybody who has seen the crowd of people at the bus stops on the ring road here knows what I am talking about. This is a serious flaw of this plan.

There are many commercial establishments on the service road when going from the intersection towards silkboard, on the left hand side. It looks like these guys will suddenly find themselves without the buffer offered by the service road. Where will the vehicles coming to these establishments park now?

The intersection of the ring road with HSR layout 24th main and surrounding roads is going to be a weird one, geometrically. 34th main intersects another road at an angle which intersects the ring road. There is also another road parallel to 24th main which intersects the ring road. Hopefully, the plans have a clear methodology to regulate this traffic flow. It is details like this the BDA tends to ignore, from my experience. 

About 150 meters ahead, we have 27th main intersecting the ring road. One wonders what the plan is at this intersection. Will there be traffic lights and regulation or is this going to be another free for all? With the wide lanes and pillars, it could be very difficult for someone from HSR 27th main to safely cut across the two BRTS lanes and catch the service road.

Another aspect that is not clear is how this new architecture of the ring road with BRTS lanes and all is going to merge with existing ring road beyond the flyovers?

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With the bus lanes coming in the middle of the road, signals are required if chaos is to be avoided at the Agara flyover. There needs to be two sets of signals – one closer to the Agara Lake where traffic coming from Sarjapur side will need to turn to go to Koramangala. The other would be at the turn towards 27^th main on HSR layout from ORR.

 

The signal near Agara Lake would need three cycles:

Cycle 1: Allow buses in both the bus lanes to proceed in opposite directions. Buses that need to turn right towards Koramangala will need to yield to traffic coming from the opposite direction.

Cycle 2: Allow vehicles coming from Sarjapur side to take a right turn towards Koramangala or a U-turn back towards Sarjapur.

Cycle 3: Allow vehicles from 24^th Main in HSR layout to go towards Koramangala or take a right turn towards Sarjapur.

 

If traffic is low, the cycles 2 and 3 above can be combined and let the vehicles yield to each other. If traffic is very heavy, a 4^th cycle may be need to allow buses coming from Koramangala to enter the bus lane.

 

The signal near 27^th Main will again need three cycles:

Cycle 1: Allow buses in both the bus lanes to proceed in opposite directions. Buses that need to turn right towards HSR 27^th main will need to yield to traffic coming from the opposite direction.

Cycle 2: Allow vehicles coming from Silkboard or Koramangala to take a right turn towards HSR 27^th main, or take a U-turn to go towards Silkboard or towards 24^th Main in HSR layout.

Cycle 3: Allow vehicles from HSR 27^th Main to take a right turn towards Sarjapur.

 

The blue print posted doesn’t indicate the location of the bus stops. However it makes a lot of sense to keep the bus stands adjacent to the bus lanes in the middle of the road. The bus stops can be accommodated between the two signals mentioned above. The stops can be built under the flyover. At the bus stops the buses may be able to move closer to the pillars allowing for one lane in the middle for buses to overtake. Even if there is not enough space to allow for a passing (overtaking) lane, it may not be a bad thing. It will at least force all of the buses to stop and pick up passengers! The lane is anyway meant only for BMTC buses.

 

The cycle of the signals at the two junctions can be kept short so that buses don’t have to unnecessarily wait at the signals after picking up passengers. Sensors can be installed on the road so that the buses get a priority green signal as soon as a bus approaches the signal. The signals can also turn red as soon as the buses pass.

 

Zebra crossings can be provided at both the signals to allow disembarking passengers to cross the road safely. Pedestrian signals can also be provided at these locations to allow pedestrians a safe passage across the streets.

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In my previous posting, I missed the traffic on the service road from Sarjapur side towards Silkboard, and on the service road from Silkboard towards Sarjapur. They may require one more cycle in both signals. If there are not many buses making right turns from the bus lanes, they can be accommodated along with Cycle 1 at both the signals. 

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First of all, thank you citizenmatters, really appreciate them sharing the info they got out via RTI. Good stuff.

Are there more diagrams? The picture for Agara flyover is showing only structural details, there may be a separate diagram showing only the amenities (signals, bus stands, service road alterations).

Heartening to see BRTS lanes there. So BDA has not forgotten about BRT on ORR. But do notice that in case of Iblur flyover, while regular ORR traffic towards silk board/agara gets to "fly" over , the BRTS lane stays on ground and has to hit a signal. Both the BRTS lanes are clearly marked on the ground.

Actually, that is fair enough, because the bus anyway has to stop at the bus stand. So why not put the bus stand right near the signal. Thats what has been designed for Iblur flyover. But then the signal will need to have priority for bus so that we avoid the "double wait", one for dropping off passengers and other to wait for the green light.

Net net, the biggest learning out of these designs is that someone at BDA is actively thinking BRTS, and its the center-lanes design. We need to find the man in charge of BRTS and grill out more details.

[have edited this later - I had got the Agara flyover design completely wrong]

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Naveen, you see two elevated stretches for two way traffic on Outer Ring Road.

Sanjay - you say "three lane elevated path" for through traffic on ORR.

I was at the site today, it seems clear that there are two separate elevated stretches with two lanes each to carry traffic over the merge with Sarjapur Road coming from Koramangala, 24th main and 27th main.

The drawing shows two BRTS lanes on surface, and under the two elevated sections.

How many signals will the BRTS lanes have at this spot? Since pedestrian traffic here is heavy (already pointed out by Sanjay), you would need planning to get people to and fromthe BRTS bus stand.

Center lane BRTS vs Edge lane BRTS - what are the pros and cons? Does anyone have some knowledge to share?

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I thought that each flyover at Agara is 3 lanes because the Iblur drawing shows 3 lanes for a 11m wide bridge.  The Agara bridge is also 11m wide for each leg (12m - 0.5m on each sides for the crash barrier). 3.3m seems to be  close to one lane width in all these reports.

If you look in the Agara drawings, there are two more documents that we must try to get a hold of for improved understanding

(a) Part 2 of the drawing NC/BDA/AGARA/SD-02/ SHEET 2 of 2

(b)Report from Nagesh Consulotants (NC) No. NC/BDA/AGARA/SR-01

We may have a better insight into the planning process from these documents.  I should file an RTI for these. Downloaded all the forms from BDA website, but waiting for some free time to go and get the DD/MO for Rs 10.  I'll try to do it this weekend.

PS: A design criteria quoted is IRS:86-1983.  How old are these standards?

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SB - There will most likely be only one signalled intersection at each location (Iblur & Agara) to deal with traffic conflicts after the flyovers are built.

At Agara, the signal intersection may likely be positioned at the intersection of 24th main & the road to Koramangala. This may not pose hurdles since traffic volumes will be much reduced once the ORR traffic is out of the way. Pedestrian movements also may not be unduly hampered due to the lower levels of traffic. Thus, the bus stops at the median will also be acceptable.

A gap may be provided in the median under the flyover to facilitate entry & exit to 27th main but no signal, or U-turns further away may be provided to avoid conflicts - you will notice on the drawing that the flyover is longer to allow it to pass over the 27th main intersection. In any case, this may not hamper bus movements much as traffic turning right into 27th main will not be much, at least, as of now.

The problem with street-edge busways is that they will need to be carried in the same way (at the edges) all along ORR. If the bus lanes have to be moved to the median later at some part along ORR after the flyover/s, it would require an underpass to allow other traffic to move freely without conflicts with buses, particularly since there will be heavy traffic on ORR, all the time.

I think BDA is planning for these bus lanes in way of the flyover/s only in response to what the CTTP has prescribed. In case BRT along ORR becomes a reality at some time in the future, then provisions to accommodate them would be in place here - that's all, I guess !

I doubt very much if a complete ORR median BRT is on the cards - not yet anyway, since there is still a lot to be done at most other locations & on open stretches, too (such as cordoning off bus lanes, planning stops, pedestrian facilities, etc).

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Dear Skumars,  I think the flyover at Agara only takes the ring road through traffic over the 24th main and ring road intersection.  The intersection continues to be a 4 way intersection, however, the volume of traffic on all 4 legs may not be very well balanced.  I think you may have left out couple of traffic stream in your signal cycle analysis.

I am convinced that the signaling design and traffic routing here will decide the success or failure of this structure for the traffic streams that are not going through on the ring road on the flyover. Since there are two main inlets to HSR, 150 metres apart and BRTS implemented here, I think a traffic expert with some solid data  and future projections will be able to design a proper traffic flow.  One example could be to only allow right turn for HSR traffic coming from 24th main side into the rign road and similarly, only allowing traffic into HSR from the Sarjapur bound ring road section along 27th main and having synchronized signals between the two intersections.  Just a wild thought.  Like I said, an expert with solid traffic count data, future projections should design this.  One goal should be  to see how the bus lanes do not get bogged down in negotiating signals, bus stops and cross traffic while other traffic flows comfortably above.  There goes your incentive for a BRTS down the drain.

We all know how unregulated intersections work in Bangalore. Nobody yields to anybody else and eventually everything gets slowed down.  It is also unsafe. That is why I am afraid of an unregulated 27th main intersection.  However, having two signals 150 metres apart could also result in a poor design.

 

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Since, the flyover at the agara junction is complete now and all functional. Its not my regular commute road, but I have been through this route quite a few times in past few weeks, and so thought of waking up this thread again.

There are couple of issues here -

(1) Road below the flyover, be it from koramangala to Iblur side, or service road (now main road) in front of the sobha & other apartments, were not at all recontructed again after being damaged while flyover construction. They are not at all safe for motorists at all.

(2) Also, nothing is being done for pedestrians also, the drains cover along the service road is also not complete.

(3) Commuters waiting for buses at bus-stops below the flyover also stand in patches here and there, buses doesn't stop at designated stops.

(4) No priority for buses at all.

(5) Bus drivers and even other drivers (want to go towards koramangala) also block all the lanes at the signal, blocks all the straight traffic as well.

(6) Traffic coming from Iblur, wanting to take that single lane road at the start of the flyover, huge jam happens, because of the bad design of the flyover. It blocks traffic going on the flyover as well, as 2 lanes are waiting to enter into 1 lane below the flyover.

I suggest, need to visit this place and have a review.

BDA is all completing flyovers but not a single flyover, they had repaired (if not re-constructed) the roads below and around the flyover, which got damaged during the construction.

Deepak

 

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