HIGHWAY ENGINEERING

AT HIGH ALTITUDES

INDIA- TYPES OF TERRAINS

INDIA

PlainsDesert

Coast Mountains

INCA ROADWAYS

INTRODUCTION

• A country's progress is defined by it’s roadnetwork.

• Constructing and maintaining the roadways in theHIGH ALTITUDE REGIONS have been a majorchallenge for the engineers. Almost everymonsoon, roadways get blocked due to landslideand in winter time roadways get blocked due toheavy snowfall.

• The HIGH ALTITUDE REGIONS are characterizedby extremely steep and rugged slopes.

Contd………• The requirement of constructing roadways near

HAAs region was felt during the 1950s when it was found that the lofty Himalayan Mountains were no longer effective as a natural protective wall.

• BRO has till date constructed 28,342 km of formation cutting, 32,885 km of surfacing, 12,200 metres of permanent bridges and has undertaken Rs 2039 crore worth of permanent works. Over 75 per cent of BRO’s road construction projects are in High Altitude Areas (HAAs). It is presently building 2,764 km of a total of 5,061 km road length in India’s north-eastern state of Arunachal Pradesh alone.

Categories of roadway construction based ongeographical and regional considerations:

• Roadway construction in normal terrain and weather condition

• Roadway constructions in extremely hot weather condition

• Roadway construction in hilly areas

• Roadway construction in extremely cold weather condition including at high altitudes.

Roadway construction

at

High Altitude Areas

Nilgiri hills region

The Himalayan region

• The special attention and treatment for roadwayconstruction at high altitudes starts right from

> mobilization of resources,

> selection of camping sites,

> suitably insulated accommodation,

> selection and procurement of machinery and equipment

> right type of fuel

> lubricants for the machinery and vehicles,

> appropriate grade of bitumen

> suitable type of cement properly acclimatized workers,

> suitable clothing’s and gear for the workers

DESIGN ASPECT• While designing HAAs roads special consideration such

as, balanced cut and fill with a retaining wall, use of reinforced soil to minimize earthworks and provision of adequate erosion control measures.

• Geometric design for transportation facilities includes the design of

> Geometric cross sections > Horizontal alignment > Vertical alignment> Superelevation> Intersections

• the goals of geometric design are to maximize the comfort, safety, and economy of facilities, while minimizing their environmental impacts.

Retaining Wall & Erosion control measures

DESIGN ASPECT

• Superelevation = e = (v2/gR)-f

• The regions falling in extremely cold weatherconditions experience frequent snowfallsduring winters and sometimes even after thewinters or before the onset of winter.

• In the road sections susceptible to snowfall,the road alignment, as far as practicable,should be fixed on the sunny race.

SNOW GALLERIES AND AVALANCHE CONTROL STRUCTURES

Contd……….• In heavy snowfall reaches, special structures such

as snow galleries and avalanche controlstructures are constructed to allow the snowmass to slide over the gallery roof withoutinducing impacts of loads on the road structure.

• During thawing season, there is heavy dischargeof water in the drains due to melting of snowcausing erosion to the sides and the bed of thedrain.

• So we should provide lined drains in the snowfallreaches of the road.

Contd...

• The penetration grade of the bitumen for thepavement and the job mix design for thebituminous works as also for the concreteworks have to be selected taking intoconsideration the ambient temperature andthe working conditions prevailing in the area.

• Use of polymers in the bituminous mix help ascrack resistant and anti strapping agents.

CONSTRUCTION ASPECTS

• The low temperature poses numerous constructionproblems, particularly for the bituminous and concreteworks.

• In case of construction of embankments and subgrade,excavation becomes difficult as the earthen layersimmediately below the surface are found to be frozen.

• The bituminous works or concrete works are not to beundertaken when the rising ambient temperature is <5oC or the falling temperature is < 10oC.

• Due to rapid loss in temperature of bituminous mix,the mixing plant should be located very close to thework site.

Contd…• To complete the compaction within very short duration

after spreading of the mix, we need adequate extracompaction equipment i.e. tandem rollers, vibratoryrollers, pneumatic rollers.

• The experience from concreting at normal temperaturecannot be used directly under the cold weathercondition, as the hardening period before removal offormwork is increased in this case.

• Timber formwork is preferable over the steel formworkin cold weather condition and at high altitudes.

• To get the required strength in short period we can userapid hardening Portland cement or acceleratingadmixtures.

Contd…..

• Normally, warm water is used for preparingthe concrete mix.

• During periods of freezing or near freezingconditions, water curing is not necessary.

• 'Set-Accelerating' ADMIXTURE are used.

Contd..

• Materials used for the insulation of concrete from cold and also for the curing of concrete are:

--insulating board.

--saw dust.

--timber planks.

--damp sand.

--wheat stalks.

--commercial blanket.

Factors affecting the roadways construction at high altitudes

• The Himalayan regions are characterized by extremely steep and rugged slopes with frequent landslides.

• Some of the factors identified to be responsible for the frequent landslides in these regions are

steep slopestoe erosion by rivers heavy rainfallmelting of snow at high altitudeloss of vegetationearthquake mining unplanned urbanization

Khardung La PASS(18,379 ft)

MAINTENANCE

• In the snow affected areas, special recovery loamscomprising of cranes and trained crews are to bepositioned at identified location to remove theaccidental vehicles.

• Transverse cracks appearing on the wearing coursesurface must be sealed or repaired periodically.

• Common salt or calcium chloride can be used for snowmelting.

• Roadside drains and opening of culverts must becleaned periodically.

• Resources are to be positioned for clearing the slides.

• Special goggles are to be provided to the workers toprotect against the snow glare.

Road heating system• Road heating systems have been in development for

some years, with variations undergoing trials and in operational use.

• Trials in the UK are being undertaken usingunderground “energy reservoirs” which transfer solarenergy collected from the road surface into useablepower. Stored heat from the collectors can then beused to heat the road in winter, helping prevent thebuild-up of ice and snow.

• Gas-fired systems use gas supplied by a utility provider,and as such are usually a less expensive option. Snowand ice is melted by sending antifreeze that has beenwarmed by a boiler through special nylon resin pipingvia circulating pump.

“A word for change”Solar Roadways

Generally the Solar Roadways will:-1. Create an intelligent, secure highway infrastructure that pays for itself. 2. Create an intelligent, secure, decentralized, self-healing power grid. 3. Eliminate the need for coal-fired or nuclear power plants. 4. End our dependency on oil and other fossil fuels (oil, coal and natural

gas). 5. Cut our nation’s greenhouse gas emissions by over 50%. 6. Provide safer driving conditions. 7. Snow & ice management 8. Traffic management 9. Wild life protection 10. National security 11. Usage of recycled material

Contd…

• Each Solar Road Panel uses some of its own power to light up embedded LEDs, which “paint” the road lines from beneath the road surface. This feature also allows messages to be spelled out on the road surface, such as “SLOW DOWN”, or “ACCIDENT AHEAD”. Road lines can be instantly “repainted” to direct traffic to a single lane or to detour. This eliminates the need for cones or flares. Better visibility at night with the road lines illuminated, it will be like driving on a well-lit runway.

Solar roadways

Conclusion

• The idea is to design and maintain a feasible roadway at high altitude areas, which will be able to structurally withstand traffic loading and operate as a test platform for future structural testing. This can be accomplished by assessing the overall design requirements of such roadway and working through each major segment of the design. Setting up of a network of new roads is essential in the so far inaccessible highlands especially in the Himalayan regions, and to introduce new technology.

Reference

• Wikipedia.org/highway engineering

• Google.com/road construction at high altitude• LANDSLIDES - INVESTIGATIONS AND MITIGATION IN

EASTERN HIMALAYAN REGION A. SENGUPTA* , S. GUPTA** & K. ANBARASU**

Thank you