Type Designs for Highway Kilometre Stones (Second Revision)
1980 Edition

IRC SP 8: Overview and Primary Guidelines

1. Kilometre Marker Inscriptions (Clause 4.2)

• This pattern repeats for further kilometre stones.
• Numbers are to be displayed using international Arabic numerals.

2. Letter and Numeral Dimensions (Clause 5.1)

3. Clearances and Spacing (Clause 5.4)

• Letter and numeral spacing depends on coding and heights (refer Table 1).

4. Colour Specifications (Clause 6.1)

• Background: White
• Text (letters & numerals): Black
• Semi-circular area:
  • National Highways: Canary Yellow (IS Shade 309)
  • State Highways: Brilliant Green (IS Shade 221)
  • Major District Roads: White
• Route numbers on semi-circular part:
  • Black on Canary Yellow/White
  • White on Brilliant Green

5. Table 1: Character Spacing Codes

(a) Letter-to-Letter Code Numbers

IRC SP 8: Structural Aspects of Kilometre Markers

While explicit formulas are not provided, the design generally follows these principles:

1. Materials and Dimensions:

• Commonly constructed using concrete or natural stone.
• Height ranges between 0.75 m to 1.0 m above ground level.
• Cross-section typically rectangular or trapezoidal to enhance stability.
• Base width approximately 0.3 m to 0.4 m for adequate support.

2. Structural Design Considerations:

• Designed to withstand wind pressures and vehicle impacts.
• Wind-induced overturning moment estimated using cantilever beam principles:

[ M = P \times h ]

Where:

• ( P ) = Wind force (Newtons)

• ( h ) = Height of the stone (meters)

• Wind force ( P ) calculation:

[ P = C_d \times A \times \rho \times \frac{V^2}{2} ]

Where:

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

3. Typical Type Designs:

4. Installation Guidelines:

• Embedded depth between 0.3 m to 0.5 m for stability.
• Foundation must prevent tipping or subsidence.

flowchart LR
    A[Calculate Wind Load] --> B[Compute Wind Force P]
    B --> C[Determine Overturning Moment M = P x h]
    C --> D[Design Base Width and Embedment Depth]
    D --> E[Select Suitable Material and Shape]

IRC SP 8: Recommended Materials for Kilometre Markers

Although the code does not explicitly specify materials, standard practices and IRC guidelines recommend:

Material Characteristics:

• Use of durable, weather-resistant substances such as cement concrete, natural stone, or precast concrete slabs.
• Recommended concrete grade is minimum M20 (mix ratio 1:1.5:3) for strength and longevity.
• Typical dimensions around 60 cm height, 30 cm width, and 15 cm thickness.
• Surface should be smooth and painted white or with reflective coating to enhance visibility.
• Reinforcement with mild steel bars (6 mm diameter) may be employed for added durability.

Concrete Mix Proportions:

Additional Recommendations:

• Apply white reflective paint on inscriptions.
• Maintain sharp edges for visibility.
• Ensure firm embedment to resist displacements.

flowchart LR
    A[Material Choice] --> B[Cement Concrete]
    A --> C[Natural Stone]
    B --> D[Concrete Mix: M20]
    D --> E[Proportion 1:1.5:3]
    B --> F[Reinforcement: 6 mm Steel Bars]
    A --> G[Surface Finish: White Reflective Paint]

This approach guarantees longevity, visibility, and adherence to IRC standards.

IRC SP 8: Guidelines on Script Usage and Inscription Order on Kilometre Markers

1. Script and Sequence (Clause 4.2)

• Only one script is to be used per stone.
• Fifth kilometre markers display inscriptions exclusively in Roman script.

2. Letter and Numeral Sizes (Clause 5.1)

3. Spacing Between Characters (Table 1)

• Use Tables 1(a), 1(b), and 1(c) to determine spacing:
  • Identify code number based on pairs of letters/numerals.
  • Use the code number and character height to find spacing in millimeters.

Example Spacing (mm):

4. Colour Details (Clause 6.1)

• Background: White
• Text: Black
• Semi-circular section colors:
  • National Highways: Canary Yellow (IS Shade 309)
  • State Highways: Brilliant Green (IS Shade 221)
  • Major District Roads: White

IRC SP 8: Specifications for Letter and Numeral Sizes and Spacing on Kilometre Markers

Core Dimensions:

• Height of Letters (Place Names): 80 mm
• Height of Kilometre Numerals: 130 mm
• Height of Route Number Numerals: 100 mm

Clearances and Spacing:

• Numerals must be in international Arabic form; local or Devanagari numerals are not permitted.

Letter and Numeral Spacing Procedure:

1. Identify the code number for a pair of adjacent letters or numerals using Tables 1(a) and 1(b).
2. Refer to Table 1(c) to find the required spacing in millimeters based on the code number and character height.

Letter Groupings and Code Numbers:

• Letters are divided into three groups (e.g., B, D, E,...; C, G, O,...; A, J, T,...) with code numbers ranging from 1 to 4 depending on their pairings.
• Numerals categorized as (1,5), (2,3,6,8,9,0), and (4,7) with corresponding code numbers.

Additional Considerations:

• For lengthy names, letter thickness and spacing may be reduced, but height must remain consistent.
• Non-Roman scripts should maintain traditional styles, ensuring spacing is at least equal to stroke thickness.
• Numerals are inscribed on the face towards the carriageway; digits may be stacked vertically if the stone's width is limited.

flowchart TD
    A[Select preceding character] --> B[Identify following character]
    B --> C[Determine code number from Tables 1(a)/1(b)]
    C --> D[Lookup spacing in Table 1(c)]

IRC SP 8 - Colour Coding for Kilometre Markers

Specifications (Clause 6.1):

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

Letter and Numeral Dimensions (Clause 5.1):

Spacing Between Characters (Table 1):

• Spacing depends on character height and adjacent character pairs.
• Use Tables 1(a) and 1(b) to find the code number, then Table 1(c) for spacing in millimeters.

Example:

Visual Summary:

graph TD
    A[Kilometre Marker] --> B[White Background]
    A --> C[Semi-circular Section]
    C --> D{Road Type}
    D -->|National Highway| E[Canary Yellow]
    D -->|State Highway| F[Brilliant Green]
    D -->|Major District Road| G[White]
    A --> H[Black Inscription]
    C --> I[Route Number Colour Based on Background]

Kilometre Marker Location and Fixing Guidelines (IRC SP 8)

1. Placement:

• Markers are installed on the left side of the roadway, counting from the starting point.
• On divided highways with medians, markers must be installed on both sides independently.
• Stones should be oriented perpendicular to the road’s centerline.
• On embankments, markers are positioned beyond the shoulder, possibly elevated on platforms.
• In cut sections, stones must be placed clear of shoulders and drainage channels.

2. Design and Inscriptions:

• Adhere to Type Designs illustrated in Plates 1, 2, and 3.
• Use international Arabic numerals for kilometre numbers; avoid local or Devanagari numerals.
• Kilometre numbers face the carriageway; digits can be vertically stacked if stone width is limited.
• Place names inscribed according to the script sequence outlined in Clause 4.2:

• For Other District and Village Roads, inscriptions may be in Hindi or regional languages; Roman script is optional.

3. Size and Spacing:

• Letter and numeral spacing must follow Table 1 (code-based and dependent on character pairs and height).

4. Colour Scheme:

• Background: White
• Text: 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-circular part: Black on yellow/white, white on green.

5. Summary Table for Spacing (mm):

IRC SP 8: Detailed Spacing Tables for Letters and Numerals

Specifications:

• Letter height (place names): 80 mm
• Numeral height (kilometre numbers): 130 mm
• Numeral height (route numbers): 100 mm
• Clearances:
  • Top: 50 mm
  • Bottom: 75 mm
  • Sides: 50 mm
  • Between lines: 50 mm

Horizontal Spacing Between Characters:

Defined as the distance from the right edge of the preceding character to the left edge of the following character.

Step 1: Determine Code Number from Character Pairs (Tables 1a & 1b)

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

(Refer to the full Table 1a for precise details)

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

(Refer to the full Table 1b for comprehensive codes)

Step 2: Use Code Number to Find Spacing from Table 1(c)