National Rural Infrastructure Development Agency

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Research Areas

Preamble

The Central Road Research Institute, New Delhi, is the pioneering highway engineering research organisation of the country, carrying out research and development activities in the area of road and road transportation. The institute is housed in a huge complex with a vast variety of infrastructural facilities to undertake material testing, research and consultancy activities related to roads and runways, traffic & transportation, bridges & geotechnical aspects. The institute has also got test-track facilities to conduct experimental studies under simulated field conditions of road pavements.

Over the years, CRRI has developed a number of technologies in different areas of roads and road transportation. These technologies are economical in adoption and possess excellence to be competitive at international level. Most of these technologies have been successfully used in finding solution to many field problems connected with roads, road transportation and bridges referred to CRRI by a large number of clients belonging to Government, Public and Private sectors.

To build up a close rapport between CRRI and the user agencies, it was felt purposeful to bring out a small compendium on the technologies/know-how developed by CRRI since five decades. This compendium provides ready and consolidated information to the user agencies to enable them to avail themselves of the CRRI expertise. This document will also give an opportunity to the users to suggest R&D projects which could be useful in solving their problems anticipated in the coming years.


(A. K. Gupta)
Director

HIGHWAY PAVEMENT DESIGN & CONSTRUCTION AND MAINTENANCE

Design specification of road pavements in the following problematic areas were framed:

  • Expansive Clays
  • Water Logging
  • Rubbish Fills or Refuse Dumps
  • Sandy Terrains
  • Marshy Conditions
  • High altitude, Snow Fall

Design of pavements under varying geological, climatic and traffic conditions

  • Precast concrete block pavement – A new pavement system for sandy terrain

A new pavement system consist of hollow precast blocks with inter-connected dowel for construction of roads on a sandy subgrade and for low volume traffic (upto 200 commercial vehicles per day) has been developed.

  • Interlocking concrete block pavement

CRRI has set up infrastructure and developed expertise for interlocking

concrete block paving (ICBP) technology for special purpose paving applications. The new system is

environment-friendly and time-saving, and can be applied at locations where conventional pavements are less durable due to adverse traffic and environmental conditions. It incorporates the advantages of in-situ cement concrete pavement like structural rigidity, durability and resistance to abrasion, while at the same time obviating its disadvantages like thermal expansion, cracking, warping etc. It can be recycled upto 90 per cent and so has high salvage value. The maintenance requirements of ICBP technique are very low.

Choice of grade of binder for different climatic zones

CRRI recommended different grades of bitumens for different traffic intensitites for two distinct ranges of temperature, one is for temperature les s than 20° C.

Design of flexible pavement for heavywheel load assemblies

A new procedure for the design of flexible pavement carrying heavy multiple wheel assemblies in factory area evolved.

Benkelman beam deflection method for evaluation of structural capacity of existing pavement

Benkelman beam deflection method

Instrumentation

  • Automatic Road Unevenness Indicator for pavement evaluation.
  • Profilograph for surface characteristic measurement.
  • Bump Integrator for surface characteristic measurement.
  • Vertical profile meter for on board vertical gradients of roads
  • Axle Mounted system for on board measurement of road surface roughness
Automatic Road Unevenness recorder
  • Microprocessor based nuclear density and moisture meter for in situ measurement of density and moisture contents of subgrade and other pavement materials.
  • Deflection gauge for measuring pavement layer deflections under dynamic loads.
  • Soil settlement gauge for measuring soil settlements in earthen embankments
  • Road geometrics measuring system for on measurement of gradient, curvature and road surface roughness.
  • CRRI Impact Tester for filed CBR measurement and compaction control.
Automatic Road Unevenness recorder

PAVEMENT MANAGEMENT & ROAD INVESTMENT POLICIES

Road user cost models for Indian conditions Models for different road user cost components (fuel consumption, tyre wear, etc.) for different types of road vehicles have been developed. These models represent typical road and traffic conditions prevailing in the country.

Models for different road use cost components

Traffic simulation modeling for inter urban roads under Indian conditions A technique to assess traffic flow characteristics including fuel consumption, has been developed to take investment decisions with respect to geometric design, pavement management and other allied aspects of roads.

Video equipment for traffic simulation studies

Maintenance based preliminary riding quality model for trunk routes in India Models are useful for planning of short term maintenance measures for upkeep of roads and to study the affect of quality of maintenance on road deterioration. The deterioration with passage of time has been measured in terms of riding quality.

Inventorisation of National Highways This computerized inventory helps in planning and identifying spots needing improvement.

Verticle profile meter

Development of data on the spectrum of axle loads on National Highways Rationalisation of the pavement design procedures and streamlining the policies pertaining to axle load of vehicles.

Pavement deterioration models for Indian conditions Pavement deterioration models for flexible pavements for Indian conditions have been developed. These models enable the highway engineers to decide about the maintenance strategies to be adopted. A software package PDM has been developed for easy use of the models for highway engine

FOUNDATION ENGINEERING & LANDSLIDES

Stabilisation of surficial slides

  • Asphalt mulch technique
    Roots of locally growing vegetation are dibbled 15 to 22.5 cms apart in rows on the slpes to be treated. An asphalt mulch of a specified grade is spread by a suitable sprayer over the prepared slope. The asphalt mulch promotes the growth of vegetation by retaining the roots at their places. The asphaltic film gradually disintegrates with time gradually disintegrates with time and its place being gradually taken by a carpet of green vegetation.
  • Simple vegetative turfing
    Vegetative turfing not only checks the erosion of slopes but also averts the possibility of shallow failures.
  • Jute or coir nettings
    Jute/Coir nettings are quite promising techniques to control erosion and check slides of surficial nature. Subsequent to seeding of slopes with local species of grass/shrubs, jute or coir netting is laid over the slopes. This is followed by another dose of seeding as well as dibbling of grasses. The net provides innumerable miniature obstructions restricting the flow of water and thus reduces its erosion potential.
Coir netting in progress

Techniques of rock fall control

  • Use of geogrids
    Geogrid mesh is fixed onto the rock slope either by surficial bolting or by trench bolting at the top of the slope and allowed to cover the slope in a loose fashion. Rock fragments and boulders accumulating in the lower part of the mesh are cleared periodically. Tenax bi-oriented geo-grids have been successfully used as a rock fall control device in U.P. hills.
  • Horizontal drains for subsurface drainage of hill slopes
    CRRI has pioneered the use of horizontal drains by means of which water deep inside the hill slope can be removed. A rational design on the type of horizontal drains improved with slots of perforations and their installation with chucks has been developed. The horizontal drains are successfully used in Nilgiri Hills, North Easter Region and Hills of U.P. & H.P.

Subsurface drainage technique

  • Deep surface trench drains
    Deep trench drains have been used for subsurface drainage to improve the stability of slopes where seepage levels are within 5-6 m from the ground. Interconnected trenches are backfilled with well draining materials for quick drainage of seepage water.

Slope stabilization techniques using anchors, precast piles etc.

A suitable design of prestressed rock anchors was evolved for complex conditions of slope geometry, external loading, vibrations caused by blastic and other factors.

Computer aided design of reinforced earth retaining walls

A computer program has been developed for design of earth retaining structures using different types of reinforcements. The program enables to achieve on optimum design.

Landslide hazard zonation maping

Based on landslide hazard zonation studies carried out in Sikkim area and on Kathgodam Nainital Highway, landslide hazard zonation maps have been prepared to evolve a suitable maintenance management strategy to keep the hill slopes along the roads, free from landslide problem.

Ground improvement techniques

  • Use of vertical sand drains/sandwicks
    Vertical sand drains / sandwicks combined with incremental preloading have been successfully used to increase the bearing capacity of soft clay deposits by accelerating the consolidation of the clay layer.
  • Use of stone columns
    Two types of stone columns namely, composite column and reinforced columns have been designed to improve the bearing capacity of soft clays and were applied in port areas for specific field application.
  • Lime slurry injection
    Lime slurry injection technique has been developed to economically improve the performance of inadequately compacted earth fills for strengthening. Bore holes are made into the fills and lime slurry is injected under pressure through these bore holes. The requisite injection equipment and technique have been used successfully. Compacted lime piles into 10 cm to 15 cm boreholes has shown to be effective in improving the embankment behaviour.
  • Use of geotextile
    Geotextiles and other synthetic materials like jute have been used for the construction of roads on weak subgrades. These materials are used as a separator, for drainage and for strengthening the pavement structure.
Use of jute geotextile for drainage application

Field instrumentation

To monitor the stability of weak and slide prone slopes, a number of indigenous geotechnical instruments have been developed. These instruments can also be used to monitor the performance of embankments and road. Instruments developed are:

  • Composite device for the measurement of differential settlements, tilt and crack width in buildings
  • A remote control settlement gauge
  • Settlement gauges (mercury type)
  • Strain guage pore water pressure cell
  • Pointer type inclinometer
  • Strain guage type inclinometer
  • Capacitance type moisture sensor
  • Heavemeter

INNOVATIVE TECHNIQUES OF ROAD CONSTRUCTION

Techniques using soil stabilization

These techniques involve the use of local soil and soft aggregate and have advantage over conventional techniques in terms of stabilizing/strengthening of weak sub-grade soil, conservation of material resources, improved pavement performance etc.

  • Mechanical stabilized soil in sub-bases
  • Lime stabilized soil in sub-bases
  • Naturally occurring gravel/soil gravel mixtures in sub-base and base courses
  • Stabilised soil with soft aggregates in sub-base and base courses
  • Lime stabilized moorum for base course or sub-base courses
  • Magnesium oxychloride cement (MOC) stabilized soil in sub-base course
Test section with MOC stabilised soil
Lime stabilised test track
  • Techniques effecting economy in pavement constructionPrecoated aggregates for surface dressing. It improves the adhesion between aggregate and binder.
    • Built up spray grout
      This technique consists of two layer composite construction of crushed coarse aggregate with application of bituminous binder after each layer and aggregate on the tope of second layer. It is quite useful for strengthening of existing bituminous road surfaces.
    • Precoated bitumen carpet over 50mm thick bituminous macadam
      This technique consists of laying and compacting of premixed heavy seal coat surfacing over 50 mm thick bituminous macadam and is useful during rainy season.
    • Continuously reinforced concrete pavement with elastic joints
      A new technique by the provision of elastic joints enables significant reduction in cost as compared to plain concrete pavement of equivalent thickness and gives improved riding quality.
    Roller compacted concrete pavement

    Other techniques

    CONSTRUCTION MATERIALS

    Survey and evaluation of material

    Scientific use of new/improved material

    Magnesium phosphate cement for emergency repair

    Development of alternate and modified binders

    To minimise the use of bitumen in road construction, alternate materials have been developed to work as binders. These relate to:

    Utilisation of Waste Materials

    Dry mixing of processed municipal waste, fly ash, lime
    • Rolled lean cement concrete
      Semi rigid material having superior load dispersion properties as compared to conventional granular or sub base like WBM.
    • Brick sandwitch C.C. pavement
      This construction technique replace the middle layer of conventional cement concrete pavement by a relatively cheaper material such as bricks at the neutral axis level and can effect about 25 per cent saving in cement.
    • Pre-stressed concrete pavement
      Prestressing technique effects a considerable economy on the quantity of cement used and less maintenance cost though the initial cost of road is higher by 15%.
    • Fibre reinforced cement concrete pavement
      Introduction of mild steel fibres by 1.0 to 1.5% by volume in concrete improves its strength, fatigue etc. The strength improvement would result in reduction of pavement thickness requirement.
    • Roller compacted concrete pavement
      This technique uses zero slump concrete compacted by vibratory road roller. It is cost effective, fast, labour intensive and utilizes construction technique similar to asphaltic concrete pavement.
      • Thin sand asphalt surfacings
        This technique is useful where aggregate has to be brought form long distances.
      • Bitumen mixes using uncrushed gravel with or without percentage of fine aggregate
      • Air photo interpretation technique for the location of hidden deposits of road material
        Well defined and distinct airphoto patterns for the location of hidden aggregate deposits like kankar, dhandla and laterite etc. have been developed and established based on field checks. The accuracy of interpretation has been found to be of the order of 75 to 80 per cent.
      • Rapid repair material for concrete pavement
        For quick repair of cement concrete pavement, rapid setting materials like sulphur concrete and magnesium phosphate cement have been developed.
      • Polymer impregnated concrete
        Polymer impregnated concrete is used for rehabilitation of micro cracked concrete slabs and bridge decks. With very low amount of impregnated polymer, quite high strength has been achieved. Further, corrosion of reinforcing steel is totally checked.
      • Burnt clay pozzolana and lime pozzolana mixture
        Two construction materials namely burnt clay pozzolana and lme pozzolana mixture have been developed. The former can be used to replace cement to the extent of 20-25% in all cement based construction, the latter is a strength based economical substitute for cement in certain categories of civil works.
      • Use of anti-stripping agent
        Guidelines formulated on the use of anti-stripping agents.
      • Use of resins for concrete repair
        Special resin formulations have been made for emergency repair of cracks in concrete pavements.
      • Rejuvenating agents for recycling of bituminous mixes
        Various grades of recycling agents have been developed by blending a resinous product from agricultural wastes with low asphaltene bitumens and approved quality of anti-oxidants. These agents make old bituminous mixes worthy of use by restoring the deficiency in physio-chemical characteristics of oxidized bitumen and weasthered mix of existing surfacing.
      • High temperature, low temperature and lignite tars and plasticised sulphur.
      • Modified binders obtained by adding rubber, resin and polymers to bitumen to improve its properties.
      • Improvement in durability of bitumens with addition of lime-stone dust, fibres, aluminium powder and other chemicals.
      • Use of industrial wastes like lignite as alternate binder
      • Mastic asphalt obtained by adding lime stone powder and fine aggregate to bitumen used for typical locations.
      • Use of flyash
        Partial replacement of cement / sand in cement concrete by 10-20 percent flyash led to about 5-10 per cent economy in cost. Following techniques of flyash based semi-rigid base course have been evolved.
      • Lime-flaysh stabilized soil in sub-base in pavement construction
      • Lime flaysh concrete
      • Cement-flaysh concrete
      • Lean cement flaysh concrete
      • Lime-flyash water cound macadam
      • Lime-granulated blast furnace slag concrete
        Studies have indicated that lean lime-GBFS concrete 1:9.6 mix (binder : aggregate ratio) can be used as base course whereas material lime :GBFS concrete 1:6 mix (binder aggregate ratio) can be used for paving footpaths, low traffic volume roads and precast blocks to be used for shoulders and creteway construction. Moderate lime-GBFS concrete 1:6 mix) with an overlay of asphaltic concrete or plain cement concrete can be used for construction of composite pavements for high density corridors.
      • Steel slag in road construction
        Specifications have been evolved on the use of steel plant slags (cooled blast furnace slag and steel slag) in different pavement layers.
      • Use of municipal waste

        Specifications have been developed to use the processed municipal waste in road construction.

        • Lime-redmud and lime-rice husk mixes
          Studies indicated that lime-redmud and lime-rice husk stabilized soil can be used in base course.

        APPROPRIATE TECHNOLOGY FO RRURAL ROADS

        Planning model for rural roads

        A simple model to plan a rural road network with maximum connectivity and at economical cost has been developed for rural road development.

        System approach to rural road    network planning

        Appropriate specifications for rural roads

        A series of specifications developed using locally available soil materials for use in various parts of the country with climatic conditions and for different volumes and load intensities of traffic. These are:

        Water bound macadam road construction
        • Use of treated soil in place of stone or bricks in the lower layers of road pavement
        • Scientific use of naturally occurring gravel mixture in road construction
        • Providing sub-base of lime stabilized expansive soil in the construction of water bound macadam roads in black cotton soil areas.
        • Providing sub-base and base course of local non-expansive soil (Moorum Alluvial soil) stabilized with lime in the construction of water macadam road.
        • Stabilisation of soil with soft aggregates for the construction of all-weather roads in dry and wet areas.

        Improved bullock cart technology

        An improved bullock cart fitted with flexible element and needing less tractive effort has been developed.

        Improved bullock carts developed by CRRI

        Tractor bound technologies for rural road construction

        Tractor Bound Technologies have been developed for rural road construction. Where all operations, such as road pulverization, mixing and rolling can be undertaken with Tractor. These technologies not only results in economical and faster construction but also lead to the better quality of roads.

        Modified pavement design curves for rural roads

        Two sets of pavement design curves for rural roads have been developed which take into account solid wheeled carts (SWC) and give economical pavement design.

        Tractor bound technology for road construction

        Empty bitumen / oil drums for low cost culverts

        A cost effective technology for cross-drainage works in rural areas has been developed, which consists the empty bitumen/oil drums in place of conventional hume pipes.

        Low cost culverts using empty bitumen drums

        Document on rural road development in India Vol. I & II

        This document is very useful for planners, administrators and road engineers.

        Working manual (for the construction & maintenance of low volume roads)

        The manual covers the construction & maintenance aspects of rural roads, describing requirement of quality control of material and relevant laboratory and field quality control tests.

        Use of flyash in road construction

        BRIDGE ENGINEERING

        Computer aided inventory rating of bridges

        Computer programs developed for inventory rating of slab bridges, T-beam & slab bridges and analysis of through and subdivided Warren truss, parallel & curved chord pratt truss and K-type truss bridge.

        Design of R.C. retaining walls with relief Shelves

        A simple design methodology for design of RC retaining walls with relief shelves, by adopting a modifies (active) earth distribution diagram, has been developed. A set of design charts have been prepared for determining reduction in active earth pressure.

        Expansion joints for Bridges

        Three different types of improved forms of conventional expansion joints to cater for movements upto 40 mm evolved. The Institute also provides advisory consultancy for replacement of distressed expansion joints and wearing coats on bridge decks.

        Monitoring of deformations of bridges

        Suspension wire method has been developed for measurement of deflection in bridges under load. Long length gauges for measuring surface strain of finally cracked concrete beams developed. Under side pulling technique also developed for application of knife edge loads on bridge girders.

        Load test on bridge images/im24.jpg

        Design of elastomeric bearings & hi-load bearings

        Besides offering extensive testing facilities for the elastomeric bearings, the Institute has also developed a simplified design procedure for its manufacture. Studies were also done on distribution of braking force on bearing and those with dowel holes. Hi-load bearing with Cadmium-Nickel coatings on mildsteel mating surfaces of rocker and rocker-cum-roker bearings, to enhance their capacity by three times has been developed.

        Testing of Elestometric bearings

        Strengthening and rehabilitation of bridge structures

        Different rehabilitation techniques of distressed concrete members in the bridge structure have been executed which include crack filling by epoxy resins, polyester resin, crack stitching and bonded plates with 6 mm dia steel bars besides usage of epoxy bonded plates to enhance flexural or shear capacity of RCC beams.

        Slab bridges with stiffended edge beams

        Ready to use design charts for design of slab bridges with stiffened edge beams of 7.5 m wide carriageway and span length 2-12m to cater for IRC standard loadings have been developed.

        TRAFFIC & TRANSPORTATION PLANNING

        Traffic Engineering

        Grade seperated interchange

        Traffic circulation plans have also been designed for different terminal areas such as bus terminals and rail terminals.

        Parking plan proposed of domestic airport, New Delhi images
        • Design of inter-sections
          Improvement plans of different types of road intersections under varying traffic flow conditions incorporating various design features have been evolved to ensure smooth, efficient and safe movement of traffic.
        • Design of road interchanges
          Keeping in view the growing traffic flow trends in urban areas and to ensure uninterrupted flow of traffic suitable designs have been evolved for different types of road interchanges.
        • Traffic management and circulation plans
          Based on traffic and transportation studies conducted in different city sizes in India, traffic management and circulation plans for congested areas have been evolved. These plans made extensive use of traffic engineering techniques, such as one-way movements, design of signal phases, speed restriction, parking restrictions, prohibition of certain movements.
        • Parking norms and designs
        • Base on parking studies conducted parking norms for different land uses have been evolved. Parking designs have also been proposed based on optimal use of available parking spaces.
        • Uniform road signs and markings
          Standards for the various types of road signs and markings have been evolved and incorporated in various IRC standards.
        • Traffic flow characteristics
        • Based on the study of traffic flow characteristics on urban roads, temporal and spatial patterns have been established. Relationship between flow of traffic and speed also developed.
        • Capacity norms for urban roads
          Study accomplished to determine capacity norms for urban roads and these formed basis for IRC Standards for designs service volumes for different categories of urban roads.

        Transportation planning

        Traffic flow at an intersection in Delhi images

        have been made to forecast transport demand for horizon years and to prepare road network and transport plans for different city sizes in India. Studies have also been conducted to assess the mobility levels and transport problems of various populations groups in different city sizes. Methodolgies and techniques have been evolved to plan medium capacity and high capacity mass rapid transit systems for cities in India.

        • Regional and urban traffic & transportation planning
          A number of traffic & transportation studies conducted in the country have brought about greater understanding of travel characteristics of urban residents. With the expertise gained, transport sub-models incorporating socio-economic and spatial aspects have been developed. The application of these models
        • Urban goods characteristics
          Models have developed to estimate demands of urban goods movements. Studies have also been conducted to plan goods terminals.
        Traffic flow at Nagpur images

        ENVIRONMENT & ROAD SAFETY

        Testing of drivers images
        Pollution monitoring van
        • Driver evaluation techniques
          Techniques to determine driving ability of drivers based on their psycho-physical and psychological traits have been developed
        • Thermoplastic materials for road markings
          Thermoplastic material has been developed as a substitute fpor road marking paints and is comparatively cheaper keeping in view its durability
        • Environmant impact assessment (EIA)
          Guidelines and methodology has been developed to conduct EIA studies for highway projects in India.
        • Air quality evaluation
          Air pollution monitoring of CO, HC, NOx,SO2, O3 and SPM alongwith meteriological variables has been carried out in selected cities. The quality of air that one breathes can be evaluated for the given location/area.
        • Assessment of noise pollution
          Assessment of noise pollution status for various types of landuse, traffic characteristics and abatement measures.
        • Accident Investigation
          A methodology for identification of accident prone locations was developed taking into account the various parameters of road, traffic and its characteristics and the accident records.
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