How to Read a Road Construction Drawing from Scratch: Actual Project Example 1

Asad Ali

Thu, 03 Sep 2026

Road projects commonly cover large areas and may extend for several kilometres. Before measuring or pricing any item, a quantity surveyor must understand where the relevant drawing area sits within the overall project. This article explains a practical sequence for reading a road construction drawing, using an actual project example for a road tunnel beneath an airport runway.

Why Start with the Key Plan?

A drawing sheet may show only a small part of a much larger road network. Starting measurement immediately from a detailed plan can create uncertainty about the start point, end point and exact project location.

The key plan provides the broadest view of the project. It helps the reader identify:

• The overall project layout.
• Major surrounding features, such as airport runways, buildings and connecting roads.
• The specific area covered by the drawing under review.
• The relationship between the detailed work area and the wider site.

In the example, the key plan shows an airport environment with runways, buildings and roads. A highlighted red line identifies the portion being considered. This portion relates to a tunnel: the runway is above it and the tunnel runs below.

Move from the Key Plan to the Location Plan

After identifying the general project area, move to the location plan. The location plan is a zoomed-in view of the relevant section identified on the key plan.

It should be used to establish:

• Where the measured or reviewed work starts.
• Where it ends.
• The direction in which the road or tunnel alignment progresses.
• The limits of the particular drawing area.

This approach breaks the information down from a large-scale project view to a more focused work area. It is particularly useful during quantity take-off because it helps prevent omissions, duplication and measurement of the wrong location.

Understand the Overall Road Arrangement

Once the location is clear, review the overall plan for the road arrangement. In this example, the road has two carriageways:

• One side carries traffic in one direction.
• The other side carries traffic in the opposite direction.
• Each side has four lanes.

The overall plan gives context to the detailed symbols, markings and references shown on the sheet. It also helps the quantity surveyor establish whether an item applies to one carriageway, both carriageways, a specific lane or only a localised area.

Read the Drawing Title Block

The title block is one of the most important places to check before interpreting or quantifying a drawing. It identifies the discipline, work package, drawing title and drawing status.

Discipline

The discipline in this example is Civil and Site Work. Road works fall within civil works and are carried out as site works within the project.

Work Package

The work package is Road Works according to BOQ. The BOQ work package helps connect the construction information shown on the drawing with the relevant bill items for measurement, pricing and valuation.

Drawing Title

The title is stated as Orba Road Tunnel One Area Road Ceramic Marking Plan and Details.

The title indicates that the drawing is concerned with the arrangement and details of ceramic road markers. A title should always be checked because it tells the reader why the drawing was produced and what information it is intended to communicate.

Drawing Status and Project Stage

The example is identified as a shop drawing. The transcript describes three drawing stages:

1. Contract drawing: The drawing used as part of the contract documentation.
2. Shop drawing: A drawing produced after contract award for the execution phase of the project.
3. As-built drawing: A drawing prepared after the project is completed.

For measurement and construction review, it is essential to confirm the status of the drawing being used. The work in this example is stated to be executed based on the shop drawing.

Interpret the Ceramic Road Marker Information

The drawing concerns ceramic road markers, described in the lesson as yellow signs or markers installed at the side of the road. Their purpose is to provide road guidance and assist traffic management by helping vehicles identify road lines and spacing.

These markers are also referred to in the lesson as cat eyes. The plan communicates the arrangement and spacing at which the markers are to be installed along the road.

Use the Drawing Details and References

After reviewing the overall plan, examine the details shown on the drawing. Details explain the symbols and marker references used in the plan.

Examples mentioned include:

• P7 Yellow
• P15 Yellow
• P15 White

These references identify different marker types or colours. The same reference names can be traced in the BOQ when reviewing the related work items. This link between the drawing and BOQ is important for accurate quantity take-off.

Recommended Workflow for Reading and Quantifying Road Drawings

Use the following sequence whenever reviewing a road construction drawing or preparing quantities:

1. Review the key plan to understand the overall project and the location of the work area.
2. Review the location plan to establish the local limits, start point and end point.
3. Study the overall plan to understand the road layout, traffic direction, lanes and scope of the drawing.
4. Check the discipline and work package.
5. Read the drawing title to confirm the purpose of the drawing.
6. Confirm the drawing status, such as contract, shop or as-built drawing.
7. Review all details, symbols, colours and references.
8. Trace drawing references to the relevant BOQ items before taking off quantities.
9. Track completed, current and outstanding areas so that the work is measured systematically.

Key Learning Points

• Always begin with the key plan, especially on large road projects.
• Use the location plan to identify the precise limits of the work under review.
• Do not rely on a detailed drawing view without first understanding its location in the wider project.
• The title block confirms the drawing discipline, work package, purpose and status.
• Plan references such as P7 Yellow, P15 Yellow and P15 White should be checked against the BOQ.
• A structured drawing-review process supports better control of measured, ongoing and remaining work.