Road Classification
Expand CRRI
Central Road Research Institute
What is the main purpose of a reconnaissance survey?
To explore possible routes and collect general data
Define a highway alignment in one sentence.
The positioning of the centerline of a road in both horizontal and vertical planes
What is camber used for?
For drainage of rainwater from the road surface
A stretch of road in your city floods every monsoon season, damaging the pavement and delaying traffic. As a planning engineer, what is the first step you would take to prevent this?
Conduct a planning and drainage survey to check slope, camber, and surface drainage issues.
When was Nagpur Road Plan, Lucknow Road Plan initiated?
1943, 1961
Name one type of data collected during a planning survey.
Traffic volume / soil type / topography / drainage
What is an obligatory point?
A location the alignment must pass through or avoid
Define Stopping Sight Distance (SSD).
Minimum distance required to stop a vehicle safely after seeing an obstacle
A contractor proposes reducing the radius of a curve to cut construction costs. As an engineer, what risks would you highlight?
Reduced safety, higher chances of vehicle skidding, inadequate sight distance, and possible non-compliance with IRC design standards.
List three criteria used to classify roads
Traffic volume, location, function, construction material
Differentiate between preliminary and detailed surveys in one line each.
Preliminary = route selection; Detailed = exact alignment and design details
Give two examples of obligatory points to avoid.
Religious sites, graveyards, lakes, steep hills
What are assumptions for SSD?
t = 2.5 s, 1.2 m and 0.15 m heights
A newly constructed hill road has experienced two accidents due to vehicles overturning on curves during rain. What geometric and pavement-related issues would you investigate?
Check for inadequate super elevation, low surface friction, poor drainage leading to slipperiness, and improper signage.
State two key differences between a State Highway and a National Highway.
SH is maintained by state, connects districts; NH is maintained by central govt, connects major cities across states
What is the ideal sequence of surveys for a new highway?
Map - Reconnaissance → Preliminary → Detailed
What happens if the alignment passes through a flood-prone zone?
Increased construction/maintenance cost and safety issues
What are the different transition curves?
spiral, cubic parabola, and lemniscate curves
In a congested area, a road is expanded but traffic issues persist. What planning factor was likely overlooked?
Road network pattern, intersections, or traffic flow analysis
Distinguish between urban and rural road classifications in one sentence each.
Urban = based on function (arterial, collector, local); Rural = based on connectivity (NH, SH, MDR, ODR, VR)
In a planning survey, why is soil investigation important for alignment selection?
It helps assess foundation strength and pavement design feasibility
A road alignment must cross a river, a school, and an industrial zone. Which would you prioritize to pass through or avoid, and why?
Avoid the school for safety, pass through the industrial zone for accessibility, cross the river at narrowest point to reduce cost
What is the minimum radius of a horizontal curve if the design speed is 80 km/h, super elevation is 7%, and f = 0.15?
R = V² / (127(e+f)); R = 640 m
During a site inspection, you find that road signs are blocked by trees, and curves have no guardrails. What alignment and design concerns do these raise?
Poor visibility, lack of clear sight distance, and inadequate road safety features.