Estimating the Costs of Highway Works

The costs of highway improvement works are a combination of:

• The works costs (i.e. the cost for the contractor to construct the works)
• Supervision/Inspection costs (the Highway Engineer and/or Local Highway Authority costs)
• Supply costs (for items that have to be purchased from designated sources - such as traffic signals, bus shelters etc.)
• Utility diversion costs (these works may be carried out prior to and/or during the main construction works).

Additionally there will be costs associated with the design and procurement procedures as well as legal charges in the Section 278 Agreement with the Local Highway Authority to carry out the works. There are also potential costs for land acquisition and commuted sums to the Local Highway Authority for future maintenance of the highway works constructed.

Design costs are usually estimated from a database of rates for the Highway Engineer and technical support staff who will be carrying out the design. Estimates of costs from specialist designers who may be involved in the works, i.e. structural engineers, street lighting designers etc. must also be included.

Before an estimate of the works construction costs can be calculated, a bill of quantities will be produced that contains all the elements of work that will be required for the construction of the project.  Rates are then applied from a database of similar items to produce the estimate.  The database will be a combination of items from recent priced bills of quantities, and actual quotes for other items where prices are not readily available.  Additionally, rates can be obtained from other sources such as Spon's “Civil Engineering and Highway Price Book” and the Civil Engineering Contractors Association’s “Schedule of Dayworks Carried Out Incidental to Contract Work”.