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Lanes, Are They Useful?

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Can lane discipline really reduce traffic jams? Are lanes of any use? Given how things are, not as they are designed, and not unless they put some thought to it.

Real use of lanes is not to control flow in midblock sections. Providing lateral or sideways safety buffers, and segregation of flow that is changing directions are much more important reasons why lanes are required. The real value of lanes is at intersections where by proper partitioning, turning traffic can be segregated. Lanes can thus release a lot of the pressure at intersections. But lanes at intersections cannot work without lanes midblock. So lets discuss midblock lanes.

Look at Mark Pritchard's image in the right. On the road going south, strict laning( 3mtrs/lane IRC standards) would enforce exactly two lanes. But, in natural, unenforced flow, people are making much more efficient use of the road. From the image it is clear that non bus traffic can quite conveniently use 3 lanes, while buses can safely use only 2 lanes.

More cars, autos and two wheelers and cycles use the roads than buses. Designing the lanes from bus' perspective results in non optimal usage of the road. If people lined up one behind the other in two lanes, the jam would have been at least 50% longer!!

So two lane design, which is based on standards, will fail because nobody will follow it, and even if they followed it, two lane design would unnecessarily spread congestion.

But not marking lanes is not the answer. No lane marking would result in > 3 lane traffic which is dangerous because side separation between vehicles is then reduced*. So there has to be some design to enforce discipline.

What is it? Are smaller lanes the way to go? Would three lanes design - allowing only the buses to straddle two lanes work? What do you think?

[*During my days of idealism, I used to rent cycles. One day, an auto came so close to me that the right pedal of my cycle got stuck in the auto. Got wounded, had to pay 50 rs extra to the rental guy.]


silkboard's picture

we create our own rules ...

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... around these lanes? Drivers in our country form chaotic yet self organizing groups. Low speeds in the city, not enough space - make as efficient use of road width as possible (Tarle's picture and explanation above). A faster highway - better use those lane markers (a pic I took on Pune expressway - I noticed guys have learnt to stick to lanes)

tsubba's picture

City Roads Need Their Own Standards.

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Highways outside city limits are a different beast. The speeds are higher and hence lateral buffers need to be wider for safety. Moreover, the volumes are lower. Not city roads and highways within city limits.

If traffic self organizes in such a way that the design is being consistently violated, then what should be done? Where is the problem?

Is this showing that the design is flawed? Is it chaotic because you are trying to impose the wrong structure? Are you trying to solve the wrong problem with the wrong solution?

Some more illustrations:

* Joe Arnold (very instructive)

* MN Vasu (gorgeous pic) 

shas3n's picture

Uneven lanes?

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I might be taking a really vague shot here, but how about uneven lane widths? Left lane the widest and for the buses, the middle one about 2.5m (or less) for cars and the right most for bikes/autos who would anyway be comfortable at the fast lane.

In other countries the traffic is more or less homogenous so an equal lane width would work. In India the traffic is as diverse as population. We need something really specific to our needs I guess.

I heard driving in Italy, Mexico etc is equally bad and its no coincidence that they have fairly divere traffic too.



tsubba's picture

mixing objectives

186 users have liked.

segregating vehicles by type will work as long you are midblock, the moment you hit an intersection it is chaos. how will buses on the left lane turn right? and how will cars on the left turn left? you will have to work on signals then. separate signals for each type and direction. green for left lane, separate for others turning left, separate for others turning right...

more later... have to run

Visitor's picture

Some points about lane

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Some points about lane system followed in the US 1) in the US, all the vehicles move at a constant speed on the roads ( more or less equal). They stick to the upper and lower speed limits. (not the case in india, where you have bullock carts to ferraris on the same road) 2) Not only are the lanes segregated, at every intersection, there are separate lanes (new ones, the road widens)for people who want to turn. So if you continue on the road, you get your own lane. If you are turning you move to separate lane reserved for turning and wait. And there are marked entry areas to these turning lanes. if you miss that, good luck, go to the next U turn. ( not the case in india, our roads are of uniform width, whether near intersection or not) 3) the roads are designed to carry that much traffic. (Our roads carry 10 times of the traffic they are designed to carry) Basically we have an unplanned road system which is evolving ( rather very late) to the demands. Hence all this confusion about lane system. This is why we have authorities who do not strictly enforce lane system, they know that the system will not work in current scenarios and no point in enforcing it right now. "But not marking lanes is not the answer. No lane marking would result in > 3 lane traffic which is dangerous because side separation between vehicles is then reduced*. So there has to be some design to enforce discipline". It is >3 lane traffic in most roads in bangalore. For this to change two things should happen 1) Better infrastructure 2) Better discipline among people. both go hand in hand.
tsubba's picture

Different Roads

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We are discussing, improvements to existing city roads through design to increase safety and organization and if possible throughput. Your observation of uniformly wide roads is absolutely correct and was to be the subject of next discussion :). Right now midblock city road interventions is what we were discussing. Sorry for the confusion.

I think we must distinguish between US interstates(expressway), SH highways and city roads. While they all carry traffic, that distinction is important. Interstate network is an entirely different network that is overlaid on the state highway and city road network. Interstate networks are almost stand-alone and adhere to some very strict rules. State highways and city roads are more tightly connected and adhere to a different set of rules.

Interstate specs are so expensive to build that it is atleast partially funded by the US federal govt. access control, grade separation, turning lanes etc are a norm on the interstates but not on state highways and city roads.

State highways and city roads are typically about as wide as they are in India ie typically 2x2 lanes. Few 3x3 stretches and rare instances of roads wider than that*.  And there is a reason for that. You donot want to split the city with uberwide at grade roads. Grade separation on the state highways and city roads is also not the norm. Very few state highways, are developed as access controlled roads(expressways) and even then will typically fall short of interstate standards  in at least a few metrics(lower bridges, no shoulders, medians etc). Example is Garden State Parkway. While it mostly sticks to interstate designs, but is a mess in several places.

There may be some value in emulating that model of an interstate network laid over a network of state highways and city roads in Bangalore. But that is a different discussion. Here the question is, even if they are overflowing, how to improve city roads. Widening the roads at the mouth of intersections and providing turning lanes is important. What needs to be done between intersections?

Visitor's picture

1) provide alternate routes

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1) provide alternate routes for slower vehicles. In indian context you have all different classes of vehicles. The mashup of all of these on the main roads is going to be a mess. Hence you need different routes for slower vehicles. ( bullock carts) 2) stop construction vehicles from moving on the roads during peak times. I see huge cement mixers, running along the main streets during peak times. ( why cant they move the equipment at night or non peak time) 3) instill better discipline 4) have separate bus routes. the huge trailer buses from BMTC are source of many a traffic jams. have you seen the way these snake buses weave in and out of traffic and stop everywhere ? 5) build proper bus bays. They should not be near intersections. 6) have speed breakers which reduce speed but not break the vehicles. 7) reduce the number of intersections each road has. 8) now you can have lane systems.
Visitor's picture

forgot to mention - a)

160 users have liked.
forgot to mention - a) remove the cattle from the roads. b) have overhead pedestrian crossings wherever possible c) have zebra crossings d) teach people to cross roads on these.
tsubba's picture

interesting ideas.

161 users have liked.
exclusive bus routes, bay design, access control, education interesting ideas and worth further thoughts. comment guidelines

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