India - National Highways Thread (Photos/Videos only)

[m_1973]

[chillanosaurus]

I have been a spectator in this forum for some time. I have a question about medians, specially to those who have contributed to road-building.

I have noticed that in the U.S. where they have a lot of space, the median is wide and is sloped down, the idea being it will be able to slow down and collect cars which run into it. But where there is no such space (much of the autobahn), they have aluminium guardrails with vegetation in between.

I understand the needs of a flowery median and I agree with the points made here. My question is about the median being raised. That is ok inside a city where the speed limit is say 50 kmph. But a faster vehicle,specially one with large wheels, would be airborne if if hits that raised median, and will essentially be a dangerous projectile to cars on the other carriageway. Should we not lower the median to have it at the same level as the carraigeways, and add deformable aluminium guardrails?

Originally Posted by philebus

Yep, flowers and vegetation have been found to be better light filters than competing methods.

Additionally, highway vegetation and horticulture have been found to offer many other desirable features. For example,

1. Erosion management. Dry land and median without grass or flowers release dust or sand in windy conditions that limit visibility. The dust and sand can also be abrasive to intake filters and top coat of cars and other vehicles. During heavy monsoon rains, the uncovered soil can wash out and run on top of the highway/expressway, making it slippery. Vegetation helps prevent erosion.

2. Vegetation, grass, flowery plants reduces traffic noise by acting as absorbers, dampers, and by reducing echo. You will hear more echo in dry canyons, than in valleys carpeted with gardens or forest. Less noise and echo reduces driver fatigue, and the traffic is less annoying to community around highways.

3. Vegetation can improve contrast and background, making highway signs easier to read in some locations.

4. Vegetation and flowers make driving more pleasant, provide a change in scenery, and reduce psychological monotony - important for truck drivers etc.

5. In places such as Singapore, which is very densely populated, flowers and vegetation along 4/6/8/10 lane highways passing next to urban area, make the city pretty, the drive aesthetic, views from skyscrapers more attractive, improving real estate values and general urban-nature harmony.

For more reasons, see this manual on vegetation and highways from one of the states in USA. Many states here, and EU nations have similar design guidelines. See: http://www.dotd.la.gov/highways/main...Management.pdf

[philebus]

Originally Posted by chillanosaurus

I have been a spectator in this forum for some time. I have a question about medians, specially to those who have contributed to road-building.

I have noticed that in the U.S. where they have a lot of space, the median is wide and is sloped down, the idea being it will be able to slow down and collect cars which run into it. But where there is no such space (much of the autobahn), they have aluminium guardrails with vegetation in between.

I understand the needs of a flowery median and I agree with the points made here. My question is about the median being raised. That is ok inside a city where the speed limit is say 50 kmph. But a faster vehicle,specially one with large wheels, would be airborne if if hits that raised median, and will essentially be a dangerous projectile to cars on the other carriageway. Should we not lower the median to have it at the same level as the carraigeways, and add deformable aluminium guardrails?

Agreed. Sloped down medians are very useful in regions with heavy snow, as well as regions with heavy and extended monsoons/tropical storm rainfalls. They provide a way to quickly plough and dump the snow, thereby clearing the highway for safe traffic. Similarly, during heavy rains, the sloped down medians, combined with slightly tilted highway, and integrated sides - properly connected and drained, of course - can help prevent cars from accidents caused by aquaplaning / hydroplaning.

Autobahn medians are well designed indeed. Heavier traffic motorways in Germany typically have two rails, lightly travelled ones have single rail, with vegetation in both cases. They are collapsible, as you mention, and this is a big help is reducing secondary accidents and fatalities. Similar designs or modifications in New Zealand, Swiss and French Alps, Sweden etc have remarkably reduced traffic fatalities and even accident rates.

Raised medians can be good, in urban areas, particularly where pedestrians are common. The raised medians provides a means to separate traffic from pedestrians, a place for pedestrians to safely stand, prevent tires from unintentionally running over pedestrians. If a street has 6, 8 or more lanes, senior citizens and some folks who may need more time to cross the street; raised medians provide a place to cross one half of lanes, stand, wait, then cross the remaining set.

The raised medians are also a means to ensure drivers do not try to cut corners while they are turning left or right, prevent careless rushed drivers getting into lanes meant for incoming traffic, prevent dangerous left or right turns (depending on the country, whether people drive on left or right side of the road), etc.

If there is no pedestrian traffic, raised medians are rarely appropriate or economically attractive. As you mention, it can cause moving vehicles to hit them, flip over, then cause secondary accidents. Raised barriers also act as a dyke during rains, making the street collect pools or channels of flowing water, which behaves like an irrigation canal, something that is not safe. Guardrails are cheaper, faster to install, and safer for the traffic.

There are alternatives to raised medians, some of these are cheaper and more aesthetic. Competing options in urban area are: (1) slight lowering and grooving the median in most part, and installing raised medians only at intersections. (2) installing precast concrete vegetation pots / stone flower plantation cylinders / plastic composite planters every 15-25 feet. (3) using colorful bollards made of concrete / metal / recycled plastics / composites. (4) Functional art which celebrates local handicrafts / industry / rural products / culture (common in some parts of France, for example). (5) etc.

For examples and images, see: Designing medians in urban areas

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

SH-140 goes straight & SH-141 starts from here towards right



Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Construction of ROB under progress





Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

Shot Using Canon PowerShot SX40 HS on 01.12.2012

[ajithv]

SH-141 meets NH-38 (Old NH-45) at Thozhudhur





Shot Using Canon PowerShot SX40 HS on 01.12.2012

[rsrikanth05]

Nice. TN has an amazing network of [two lane] roads.