Learning from Road Layouts
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Written By asj - 4 October, 2008
Traffic
Bangalore
Roads
Pune
Mumbai
Analysis
flow
markings
entropy
signs
Dear All,
I have for some time wanted to share how planning road layouts is vital for ensuring traffic flows smoothly.
Here is the first in what I hope to make a series (and hope other contribute too) of road layouts from UK. Aim is to share these observations with our planners to reduce entropy on our roads.
A Typical cross junction in UK
Layout example 2: A typical T' Junction
Example 3: Layout of pedestrian zebra (without traffic lights) at a T-junction. The layout automatically makes the zebra more than just a pedestrian crossing, it becomes a tool for regulating traffic, allowing vehicles either joining or leaving the main road safely when traffic waits to let pedestrians cross safely - want to see a video example? My video on Zebra belongs to pedestrians has an example, wait till you see the bus stopping for pedestrian at the zebra and see how it gives a chance for another vehicle to safely cross over to a side lane.
ASJ
Case example 4: A typical roundabout, again pedestrian zebra crossings without any traffic lights help regulate the traffic (along side the right of the way rules of a roundabout).
We have yellow boxes at some jn's in Bangalore, but everybody thinks its rangoli to beautify the jn and was done so as not to waste the extra paint left over with the painters. Most of the yellow boxes not got asphalted over and dont exist anymore.
Signal Free Roads - Do you mean junction free roads? I have tried to imagine now for some hours how this will work. The only way it will work is if we had roads that did not meet each other and consequently there were no junctions.
It seems impossible and unrealistic.
Refer you to discussion on freeways are freeways and city roads are city roads (sorry can't find it quickly enough to insert the link here)
ASJ
Here is example 5 showcasing how clear road markings and signage removes conflict, establishes right of way and hence reduces entropy.
ASJ
Ok, these are case examples 6 to 8.
First, example 6, looks at bus bays
Example 7 - is a major crossroads or intersection on a 6 lane dual carriageway - note the similarities with example one at the top.
Example 8 - same dual carriageway but a demonstration of how a conflict free U turn facility is provided
ASJ
Navin,
It is complicated. Hence I suggest the need for a whole systems approach and coming up with a package. Otherwise we are left with right hand not knowing what the left hand is doing. Though this thread looks at road layouts and optimal use of finite space, I have focused on PT elsewhere. In fact I will love it for the authorities to be ruthless - the layouts above (where I show how a bus lane in direction of CBD can be introduced on a narrow 8 meter road) and recent proposal for bus lane strategy on an 80 feet wide road in Pune all enhance PT to maximum. Our roads do not typically widen (or flay) at junctions, the layouts above allows us to still manage to have pedestrian refuges without needing extra space. I also mention TDM, very vital as whatever shape and form of PT - metro/BRT/TBS - if 30% shift from vehicles to PT, without demand management, the growing population will always find those who chose to fill the void immediately.
Also there is over-estimation of how much the trains can do in contrast to buses. Vasanth is right, buses will still be needed. How many people are transported by the rather vast underground in London? How does it compare with London buses? The answer is that tubes carry 3 million on average while buses carry 6.5 million per day. I have been on days when London tubes are bursting at their seams - I have seen 3 trains go on CCTV at the gates overground before being allowed to make way downstairs to the platforms. Mumbai - buses carry 4.5 million and trains do 7 million, but the trains are packed with more than double the people the rakes are designed to carry, in effect, Mumbai trains of health and safety norms were followed would carry no more than 3 million comfortably.
Now Pune is hoping to use standrad gauge, 4 coaches trains on its Metro - same as London - the capacity is no more than 150x4. Unlike buses, trains have no scope of detours to cover wider areas and distribute themselves - they have one track and as we know in Mumbai, the system does get saturated. Mumbai can't add any more trains as currently the headway is already just 3 minutes.
Now, when I say package, I actually look at the Jigsaw called India and not Pune or Bangalore or Mumbai. Hence on separate threads I strive to emphasise need for good Development plans and development control regulations which cap city populations. Equally, to reduce and limit migration, I cry out on matters of rural V urban divide and lack of a social welfare state.
In fact in my head, its many time more complicated given that the stage is the country and not just a city.
ASJ
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