Type Designs for Highway Kilometre Stones (Second Revision)

IRC SP 8: Introduction - Key Specifications & Tables

1. Kilometre Stone Inscriptions (Clause 4.2)

• This sequence repeats for subsequent stones.
• Numerals must be in international form (Arabic numerals).

2. Letter & Numeral Sizes (Clause 5.1)

3. Spacing & Clearances (Clause 5.4)

• Spacing between letters/numerals depends on letter codes and heights (see Table 1 below).

4. Colour Scheme (Clause 6.1)

• Background: White
• Letters & Numerals: Black
• Semi-circular portion:
  • National Highways: Canary Yellow (IS Shade 309)
  • State Highways: Brilliant Green (IS Shade 221)
  • Major District Roads: White
• Route numbers on semi-circle:
  • Black on Canary Yellow/White backgrounds
  • White on Brilliant Green background

5. Table 1: Spacing Between Letters/Numerals

(a) Letter-to-Letter Code Numbers

IRC SP 8: Design of Kilometre Stones

Though IRC SP 8 does not provide explicit formulas, the design of kilometre stones generally follows these key points:

1. Material & Dimensions:

• Typically made of concrete or stone.
• Standard height: 0.75 m to 1.0 m above ground.
• Cross-section: Usually rectangular or trapezoidal for stability.
• Base width: Around 0.3 m to 0.4 m for adequate footing.

2. Structural Design Considerations:

• Designed to resist wind load and accidental vehicle impact.
• Use Cantilever beam theory for overturning moment due to wind:

[ M = P \times h ]

Where:

• ( P ) = Wind force (N)

• ( h ) = Height of stone (m)

• Wind force ( P ) can be estimated by:

[ P = C_d \times A \times \rho \times V^2 / 2 ]

Where:

• ( C_d ) = Drag coefficient (~1.2 for rectangular)
• ( A ) = Projected area (m²)
• ( \rho ) = Air density (~1.225 kg/m³)
• ( V ) = Wind velocity (m/s)

3. Type Designs (Typical):

4. Installation:

• Embedded 0.3 m to 0.5 m below ground for stability.
• Foundation designed to prevent tilting or sinking.

flowchart LR
    A[Wind Load Calculation] --> B[Calculate Wind Force P]
    B --> C[Calculate Overturning Moment M = P × h]
    C --> D[Design Base Width & Embedment]
    D --> E[Select

IRC SP 8: Materials for Kilometre Stones

Though IRC SP 8 does not explicitly specify materials in the provided context, standard practice and related IRC guidelines suggest:

Key Specifications for Materials:

• Material: Durable, weather-resistant materials such as cement concrete, stone, or precast concrete.
• Concrete Mix: Minimum M20 grade concrete (1:1.5:3 mix) for strength and durability.
• Dimensions: Typically, stones are about 60 cm height, 30 cm width, and 15 cm thickness.
• Finish: Smooth surface with white or reflective paint for visibility.
• Reinforcement: Mild steel bars (6 mm dia) may be used for durability.

Typical Concrete Mix for Kilometre Stones:

Additional Notes:

• Use white reflective paint for inscriptions.
• Ensure sharp edges for clear visibility.
• Base should be embedded firmly in the ground for stability.

flowchart LR
    A[Material Selection] --> B[Cement Concrete]
    A --> C[Stone]
    B --> D[Mix Design: M20]
    D --> E[1:1.5:3]
    B --> F[Reinforcement: 6mm bars]
    A --> G[Finish: White Paint]

This ensures durability, visibility, and compliance with IRC standards for highway kilometre stones.

IRC SP 8: Script and Sequence of Inscription on Kilometre Stones

1. Script & Sequence (Clause 4.2)

• Only one script per stone.
• Fifth km stones: Roman script only, showing terminal & intermediate towns.

2. Letter & Numeral Sizes (Clause 5.1)

3. Spacing Between Letters/Numerals (Table 1)

• Use Tables 1(a), 1(b), 1(c) for spacing calculation:
  • Find code number from letter/numeral pairs (1a & 1b)
  • Lookup spacing in mm for height (1c)

Example:

4. Colour Specifications (Clause 6.1)

• Background: White
• Letters/Numerals: Black
• Semi-circular portion:
  • National Highways: Canary Yellow (IS Shade 309)
  • State Highways: Brilliant Green (IS Shade 221)
  • Major District Roads: White

IRC SP 8: Size, Shape & Spacing of Letters/Numerals on Kilometre Stones

Key Specifications:

• Letter Heights:

  • Place Names: 80 mm
  • Kilometrage Numerals: 130 mm
  • Route Numbers: 100 mm

• Spacing (Clearances):

  • Top: 50 mm
  • Bottom: 75 mm
  • Sides: 50 mm
  • Between lines: 50 mm

• Numerals: Use international form of Indian numerals only (no Devnagri/local numerals).

Spacing Between Letters/Numerals

1. Determine Code Number from Tables 1(a) & 1(b) based on the preceding and following letter/numeral.
2. Use Table 1(c) to find spacing in mm for the given letter/numeral height and code number.

Letter-to-Letter & Numeral-to-Numeral Code Numbers

• Letters grouped into 3 sets (e.g., B,D,E,...; C,G,O,...; A,J,T,...), code numbers vary from 1 to 4 depending on letter pairs.
• Numerals grouped as (1,5), (2,3,6,8,9,0), (4,7) with code numbers 1 to 4.

Additional Notes:

• For long names, reduce letter thickness and spacing but maintain height.
• Letters in non-Roman scripts follow their usual style; spacing ≥ stroke thickness.
• Numerals on stone face carriageway side, digits stacked vertically if thin stone.

flowchart TD
    A[Select Preceding Letter/Numeral] --> B[Identify Following Letter/Numeral]
    B --> C[Find Code Number from Table 1(a)/1(b

IRC SP 8 - Colour of Background and Inscription on Kilometre Stones

Key Specifications (Clause 6.1):

• Background Colour: White for main body of the kilometre stone.
• Inscription Colour: Black letters and numerals for station names and distances.
• Semi-circular Portion Colour:
  • National Highways: Canary Yellow (IS Shade 309)
  • State Highways: Brilliant Green (IS Shade 221)
  • Major District Roads: White
• Route Numbers on Semi-circular Portion:
  • Black on Canary Yellow and White backgrounds
  • White on Brilliant Green background

Letter and Numeral Sizes (Clause 5.1):

Spacing Between Letters/Numerals (Table 1):

• Spacing depends on letter/numeral height and letter/numeral pairs.
• Use Table 1(a) and 1(b) to find code number for letter/numeral pairs.
• Use Table 1(c) to convert code number to spacing in mm.

Example for spacing calculation:

Summary Diagram:

graph TD
    A[Kilometre Stone] --> B[Background: White]
    A --> C[Semi-circular Portion]
    C --> D{Road Type}
    D -->|National Highway| E[Canary Yellow (IS Shade 309)]
    D -->|State Highway| F[Brilliant Green (IS Shade 221)]
    D -->|Major District Road| G[White]
    A --> H[Inscription: Black letters/numerals]
    C --> I{Route

Location and Fixing of Kilometre Stones (IRC SP 8)

1. Location:

• Kilometre stones are fixed on the left-hand side of the road from the starting station.
• On divided roads with a median, stones are placed on both sides independently.
• Fixed at right angles to the carriageway centerline.
• On embankments: placed beyond shoulders, possibly on platforms.
• In cut sections: clear of shoulders and side drains.

2. Design & Inscription:

• Follow Type Designs in Plates 1, 2, 3.
• Numerals use international Indian numerals (not local/Devnagri).
• Kilometre number inscribed facing carriageway; digits stacked vertically if thin stone.
• Place names inscribed in scripts per sequence (Clause 4.2):

• For Other District/Village Roads, inscription may be only in Hindi or regional language; Roman script optional.

3. Size & Spacing:

• Spacing between letters/numerals per Table 1 (code-based, depends on letter pairs and height).

4. Colour:

• Background: White
• Letters/numerals: Black
• Semi-circular portion:
  • National Highways: Canary Yellow (IS Shade 309)
  • State Highways: Brilliant Green (IS Shade 221)
  • Major District Roads: White
• Route numbers on semi-circle: Black on yellow/white, White on green.

5. Table 1 Summary (Spacing in mm):

|

IRC SP 8: Spacing Tables for Letters and Numerals on Kilometre Stones

Key Specifications:

• Height of letters (Place names): 80 mm
• Height of numerals (Kilometrage): 130 mm
• Height of numerals (Route numbers): 100 mm
• Clearances:
  • Top: 50 mm
  • Bottom: 75 mm
  • Sides: 50 mm
  • Between lines: 50 mm

Spacing Between Letters/Numerals:

Spacing is horizontal distance between the right edge of preceding and left edge of following character.

Step 1: Get code number from letter/number pairs (Tables 1a & 1b)

Table 1(a): Letter-to-Letter Code Numbers

(Refer to full Table 1a for exact codes)

Table 1(b): Numeral-to-Numeral Code Numbers

(Refer to full Table 1b for detailed codes)

Step 2: Use Code No. to get spacing in mm from Table 1(c)