COMMENTS

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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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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