9.1 Highway Planning and Survey

9.1 Highway Planning and Survey

Introduction to Highway Engineering

Highway engineering is a specialized branch of civil engineering that involves the planning, design, construction, operation, and maintenance of roads, bridges, and tunnels to ensure safe and efficient transportation of people and goods. The process begins with strategic planning and detailed surveys, which form the critical foundation for any successful road project. This section covers the fundamental concepts of transport modes, the evolution of Nepal's road network, road classification systems, survey methodologies, principles of highway alignment, and the governing standards that ensure safety, efficiency, and sustainability in road development.

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1. Modes of Transport

Transportation systems are categorized based on the medium they use. Each mode has distinct characteristics, advantages, and limitations.

1.1 Land Transport

1. Road Transport

   • Characteristics: Highly flexible, provides door-to-door service, involves low initial investment per vehicle.

   • Advantages: Accessibility to remote areas, suitability for short and medium distances, easy to modify routes.

   • Disadvantages: High operating cost per ton-km, lower carrying capacity, vulnerable to traffic congestion, higher accident rates, significant environmental impact (pollution, land use).

2. Rail Transport

   • Characteristics: Guided system operating on fixed tracks, high capacity, requires substantial terminal infrastructure.

   • Advantages: High efficiency for bulk goods over long distances, low operating cost per ton-km, high safety, lower energy consumption per unit.

   • Disadvantages: Very high initial capital cost, inflexible routes, not suitable for short distances or door-to-door service.

1.2 Water Transport

1. Inland Waterways (Rivers, Canals, Lakes)

   • Characteristics: Uses natural or artificial water bodies.

   • Advantages: Cheapest mode for bulky goods, high fuel efficiency, low infrastructure maintenance cost.

   • Disadvantages: Slow speed, limited by navigability (depth, currents), seasonal variations, requires complementary land transport.

2. Ocean Transport (Shipping)

   • Characteristics: For international trade across seas and oceans.

   • Advantages: Extremely high capacity (supertankers, container ships), lowest cost per ton-km for intercontinental trade.

   • Disadvantages: Very slow, requires specialized port facilities, high risk from weather and piracy.

1.3 Air Transport

• Characteristics: Fastest mode, operates in three-dimensional space.

• Advantages: Unmatched speed, essential for perishable goods and high-value items, connects distant locations across geographical barriers.

• Disadvantages: Highest operating cost per ton-km, limited cargo capacity, completely dependent on weather, requires massive airport infrastructure.

1.4 Pipeline Transport

• Characteristics: Continuous flow system for liquids, gases, and slurries.

• Advantages: Most reliable and efficient for specific commodities (oil, gas, water), low operating cost, minimal land use, low environmental impact during operation.

• Disadvantages: Extremely high initial cost, limited to specific products, inflexible once installed.

Intermodalism: Modern transport relies on the seamless integration of different modes (e.g., truck-rail-ship) using containers to optimize cost, time, and efficiency.

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2. History of Road Development in Nepal

Nepal's road development is a story of transformation from isolated tracks to a strategic national network, heavily influenced by its challenging topography.

2.1 Pre-1950s: The Era of Trails and Porterage

1. Primitive Network: Transportation was entirely dependent on foot trails (e.g., the historic salt trade route to Tibet).

2. No Wheeled Transport: The mountainous terrain made wheeled vehicles impossible. Goods were carried by porters and pack animals (mules, yaks).

3. Isolation: This lack of connectivity contributed to the economic and political isolation of various regions.

2.2 1950s-1960s: The First Strategic Roads

1. Tribhuvan Highway (1956):

   • Nepal's first strategic highway, connecting Kathmandu (Naubise) with the Indian border at Raxaul/Birgunj.

   • Constructed with Indian cooperation, it broke Kathmandu's geographical isolation and became the vital economic lifeline for the capital.

2. Siddhartha Highway (1960s):

   • Connected Pokhara in the hilly region with the Indian border at Sunauli/Bhairahawa.

   • Opened up the western region for development and tourism.

2.3 1970s-1990s: Expansion and Regional Connectivity

1. East-West Highway (Mahendra Rajmarg):

   • Initiated in the 1970s, this is Nepal's longest and most important highway, spanning approximately 1,028 km from Kakarbhitta in the east to Mahakali in the west.

   • Runs through the Terai plains, connecting all major east-west trade corridors and economic centers.

   • A backbone for national integration and economic development.

2. Prithvi Highway (1974):

   • Connected Kathmandu to Pokhara (174 km).

   • A challenging engineering feat through the hills, significantly boosting tourism and trade in the central region.

3. Arnico Highway (Sino-Nepal Friendship Highway):

   • Constructed with Chinese assistance, connecting Kathmandu to Kodari on the Tibet/China border.

   • Provided a crucial northern trade route.

2.4 2000s-Present: Modernization and Strategic Projects

1. Fast Track and Ring Roads: Projects like the Kathmandu Outer Ring Road and the planned Kathmandu-Terai/Madesh Fast Track aim to decongest the capital and improve connectivity.

2. North-South Corridors: Increased focus on building roads linking the Terai with the northern Himalayan districts and border points with China (e.g., Rasuwagadhi, Korala).

3. Strategic Roads: Development of roads in sensitive and remote border areas for security and accessibility.

4. Challenges: Despite progress, road development faces persistent challenges: difficult geography, high construction costs, susceptibility to landslides and floods, and significant maintenance burdens.

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3. Classification of Roads

Roads are classified based on various factors to facilitate planning, design, funding, and management.

3.1 Based on Function (As per MoPIT, Nepal)

1. National Highways (Strategic Roads):

   • Function: Connect major economic regions, international borders, and strategic points. Form the primary network of the country.

   • Example: East-West Highway (Mahendra Rajmarg), Tribhuvan Highway.

   • Responsibility: Government of Nepal (Department of Roads).

2. Feeder Roads:

   • Function: Connect District Headquarters to the National Highway network or to other major towns.

   • Importance: Provide accessibility for district-level administrative and economic activities.

3. District Roads:

   • Function: Roads within a district, connecting rural areas to Feeder Roads or District Headquarters.

4. Urban Roads:

   • Function: Roads within municipal boundaries (arterials, sub-arterials, collectors, local streets).

5. Special Purpose Roads:

   • Function: Roads built for specific purposes like tourism (access to national parks, trekking starting points), industrial areas, or irrigation projects.

3.2 Based on Pavement Type

1. Paved Roads:

   • Have a hard, durable surface layer (bituminous, concrete).

   • Provide all-weather access, lower rolling resistance, and better riding quality.

2. Unpaved Roads (Gravel/Earthen Roads):

   • Surface is of naturally occurring or compacted soil/gravel.

   • Lower initial cost but high maintenance, dusty in dry weather, muddy in rains, not all-weather.

3.3 Based on Geography (Topography)

1. Plain Area Roads: Design governed by drainage requirements.

2. Hilly Area Roads: Design governed by gradient and stability (cut/fill slopes) requirements.

3. Mountainous Roads: Involve extensive cutting, tunneling, and protection works. Gradient is the primary constraint.

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4. Road Survey

Road surveys are conducted in stages to gather precise data for planning and design.

4.1 Map Study (Reconnaissance)

• Purpose: To study existing maps (topographic, geological) to identify feasible corridors or corridors between the start and end points.

• Output: Several possible broad alignments are identified on the map, avoiding obvious obstacles like major rivers, steep slopes, or protected areas.

4.2 Reconnaissance Survey

• Purpose: To physically inspect the corridors identified in the map study.

• Activity: A field team walks along possible routes to assess ground conditions, geology, drainage patterns, land use, and major obstructions.

• Tools: Hand-held GPS, altimeter, compass, clinometer.

• Output: A detailed report comparing the merits and demerits of each corridor, leading to the selection of the most promising single corridor.

4.3 Preliminary Survey (Detailed Field Survey)

• Purpose: To collect all necessary data for the final design within the selected corridor.

• Activities:

  1. Traverse Survey: Establishing a control traverse along the proposed centerline.

  2. Leveling: Determining elevations along the traverse and cross-sections.

  3. Detailed Topographic Mapping: Drawing contour maps (scale 1:2500 to 1:5000) of the corridor.

  4. Soil Survey: Collecting soil samples for strength and properties.

  5. Hydrological Data: Studying streams, rivers for drainage design.

  6. Material Survey: Locating sources of construction materials (quarries, borrow pits).

• Output: Sufficient data to prepare preliminary drawings, estimate costs, and finalize the Detailed Project Report (DPR).

4.4 Location Survey (Final Location and Staking)

• Purpose: To precisely peg the final centerline on the ground as per the approved design.

• Activity: The finalized alignment from the drawings is transferred to the field using precise surveying instruments (Total Station, DGPS). All control points, curve points (TPI, TP2), and benchmarks are permanently marked.

• Output: The road is physically "set out" on the ground, ready for construction activities.

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5. Highway Alignment and Controlling Factors

Highway alignment is the position or layout of the centerline of the highway on the ground. An ideal alignment is short, easy, safe, and economical to construct and maintain.

5.1 Requirements of an Ideal Alignment

1. Short: Minimizes travel distance and time.

2. Easy: Gentle grades and curves for safe and comfortable vehicle operation.

3. Safe: Good sight distances, stable geometry to minimize accidents.

4. Economical: Lowest total cost (sum of construction cost, maintenance cost, and vehicle operating cost over its life).

5.2 Factors Controlling Alignment

1. Obligatory Points:

   • Points Through Which the Road Must Pass: Specific towns, villages, industrial centers, bridgesites, mountain passes.

   • Points Through Which the Road Must NOT Pass: Dense forests, religious sites, costly structures, unstable land (active landslides), protected wildlife areas.

2. Traffic:

   • Origin-Destination surveys dictate the desire lines. Alignment should serve the maximum traffic between major centers.

3. Geometric Design Standards:

   • Alignment must meet specified standards for gradient, curve radius, and sight distance. These are limiting factors, especially in hilly areas.

4. Topography:

   • Plains: Alignment is governed by drainage considerations. Can be straight.

   • Hills: Alignment follows the natural contour (contour road) or takes a valley route to minimize cutting/filling.

   • Mountains: Alignment may require zigzags (switchbacks), hairpin bends, or tunnels.

5. Geological and Soil Conditions:

   • Route should avoid unstable areas (landslides, rockfalls, marshes). Good foundation soil reduces pavement cost.

6. Drainage and Hydrology:

   • Road should cross rivers at right angles where possible. High flood levels must be considered for bridge decks and low-lying sections.

7. Construction and Maintenance Cost:

   • The alignment should minimize earthwork (cutting and filling) and the need for major structures (bridges, tunnels, retaining walls).

8. Environmental and Social Considerations:

   • Minimize displacement of people, damage to agricultural land, and deforestation.

   • Mitigate noise and air pollution impacts on settlements.

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6. Evaluating Alternate Alignments

Once several technically feasible alignments are developed, a systematic comparison is made to select the best one.

6.1 Basis of Comparison

A comparative statement is prepared listing key parameters for each alternative.

6.2 Key Comparison Parameters

1. Length of Road (km).

2. Construction Cost:

   • Earthwork quantity (cutting, filling).

   • Number and span of major bridges/culverts.

   • Need for tunnels or complex retaining structures.

   • Pavement cost.

3. Maintenance Cost: Estimated annual cost based on terrain and pavement type.

4. Vehicle Operating Cost (VOC):

   • Includes fuel, tire wear, depreciation, crew cost.

   • Highly dependent on gradient, curvature, and surface condition. A longer but flatter road may have lower VOC.

5. Traffic Service and Benefits:

   • Population served.

   • Development potential opened up (agricultural, industrial, tourism).

6. Geometric Standards:

   • Ruling Gradient: Steepest gradient permitted.

   • Minimum Curve Radius: Governs design speed.

   • Sight Distance: Available stopping and overtaking sight distance.

7. Safety Considerations: Accident-prone features, number of sharp curves, intersections.

8. Environmental Impact: Land acquisition, forest clearance, disruption to wildlife.

6.3 Method of Evaluation

1. Engineering Economic Analysis (Most Common):

   • Convert all future costs (construction, maintenance, VOC) and benefits (time savings, accident reduction) to their Present Worth or Equivalent Annual Cost using a discount rate.

   • Calculate the Benefit-Cost Ratio (BCR) or Net Present Value (NPV) for each alternative.

   • The alternative with the highest BCR or NPV is typically chosen, provided all other non-quantifiable factors are acceptable.

2. Weightage and Ranking Method:

   • Assign weightage factors to various parameters (e.g., cost: 40%, safety: 30%, environmental: 20%, development: 10%).

   • Score each alternative on these parameters.

   • The alternative with the highest weighted score is selected.

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7. Road Standards of Nepal

Road standards are codified specifications that ensure uniformity, safety, and desired performance. In Nepal, these are primarily governed by the Department of Roads (DOR) under the Ministry of Physical Infrastructure and Transport (MoPIT).

7.1 Key Documents and Manuals

1. Road Standards 2070 (2013):

   • The primary document specifying geometric design standards for various classes of roads in Nepal.

2. Bridge Design Code.

3. Pavement Design Guidelines.

7.2 Classification for Design (As per Road Standards 2070)

Roads are classified for design based on Design Speed and Function.

Road Class	Type of Road	Terrain	Design Speed (Km/hr)	Typical Right of Way (m)
AR	Artery (Expressway/National Hwy)	Flat/Rolling/Hill	100 / 80 / 60	50 - 60
DR	District Road (Feeder Road)	Flat/Rolling/Hill	80 / 60 / 40	30 - 40
VR	Village Road	Flat/Rolling/Hill	60 / 40 / 30	20 - 30
UR	Urban Road	-	60 - 80	Varies by street type

7.3 Key Geometric Design Standards (Summary)

1. Design Speed: The maximum safe speed that can be maintained over a specified section of road when conditions are favorable. It governs all other geometric elements.

2. Roadway Width (Carriageway):

   • Single Lane: 3.75 m

   • Two Lane: 7.0 m (2 x 3.5m lanes)

   • Shoulders: 2.5 m (paved) or 1.5 m (earthen) on major roads.

3. Gradient:

   • Ruling Gradient: The gradient commonly adopted (e.g., 1 in 30 or 3.33% in plains, 1 in 20 or 5% in hills).

   • Limiting Gradient: Steeper than ruling, used in difficult terrain where avoiding it would be very costly (e.g., 1 in 16.7 or 6% in hills).

   • Exceptional Gradient: Used for very short stretches in extreme conditions (e.g., 1 in 14 or 7%).

4. Horizontal Curves:

   • Minimum Radius: Defined for each design speed and superelevation rate (e.g., for 60 km/hr with 7% superelevation, min R ≈ 115 m).

   • Superelevation (e): Banking of the curve to counteract centrifugal force. Max. value is 7% (0.07).

   • Transition Curves: Spirals (usually) are provided between tangent and circular curve for smooth introduction of superelevation and centrifugal force.

5. Sight Distance:

   • Stopping Sight Distance (SSD): Minimum distance required for a vehicle to stop safely after the driver perceives an obstacle. Depends on design speed, driver reaction time, and friction. $SSD = 0.278 V t + \frac{V^2}{254 f}$ (V in km/hr, t=reaction time ~2.5 sec, f=longitudinal friction coefficient).

   • Overtaking Sight Distance (OSD): Required for safe overtaking on two-lane roads. Much longer than SSD.

6. Vertical Curves:

   • Summit Curves (Crest): Convex curves. Length is designed based on SSD requirements.

   • Valley Curves (Sag): Concave curves. Length is designed for rider comfort (centrifugal force) and headlight sight distance at night.

Conclusion: Highway planning and survey is a meticulous, multi-stage process that balances engineering principles with economic, social, and environmental realities. A well-planned road, aligned correctly and built to appropriate standards, is a catalyst for development, safety, and national integration—a principle clearly reflected in Nepal's ongoing journey to connect its diverse and challenging landscape.