When planning an ITS deployment for the first time, the classical approach – as with any new investment – is to determine the user's needs. For example, there may be a need to improve safety, or to manage congestion, or a combination of both – or some other traffic issues which needs managing for policy reasons.
The next step is to determine the extent of the ITS requirements that provide the control capability that meets the needs and manages the traffic appropriately:
From this assessment a business case can be developed through an analysis of costs and benefits. (See Understanding the Costs and Benefits of ITS) This is essential to ensure a healthy rate of return on the investment to justify the project – and ensure that the investment compares favourably with other transport investments. (See Project Appraisal )
Where a programme of ITS projects is envisaged, covering a number of highways and urban locations (such as a network of road intersections), developing a business case repeatedly, for each project, is time-consuming and expensive. In general, highways of the same type, that carry similar volumes of traffic – and have similar safety and congestion issues – will usually merit similar investments in ITS equipment and infrastructure to achieve a common level of service. In these circumstances it is possible to develop a “generic” business case, based on a common level of ITS provision – one that has been shown to satisfy the identified “need”, meet operational requirements and importantly, demonstrate a positive benefit/cost ratio (BCR).
Once that business case is proven, it is possible to establish a common requirement for ITS deployment on roads and highways of the same (or very similar) type. The traffic and other site-specific parameters that justify this level of provision can be quantified and applied as a check-list or formula (for example, by measuring traffic flow data and accident and congestion records).
Through sensitivity testing, the range for each parameter – where the business case remains positive – can be determined to establish minimum qualifying criteria. Any road meeting or exceeding the prescribed criteria would justify having the same level of ITS provision as the project for which the business case was first developed showing a positive BCR. That level of ITS provision can then become the accepted requirement for highways and locations of the same type.
Having a common level of provision on roads of similar types and with similar levels of traffic has other benefits besides the time and expenditure savings arising from not having had to undertake a cost-benefit analysis or develop a business case for each project:
Adopting a policy to specify uniform levels of ITS provision has the advantage of reducing project design and preparation costs and other savings. It is essential to avoid technology lock-in (becoming tied into the current generation of technology). This can be avoided by specifying functionality and performance and making use of non-propriety (open) interface standards.
Where ITS is being deployed for the first time there is unlikely to be a Traffic Management Centre (TMC). In these circumstances the first ITS project will be the commissioning of a TMC of such a size as neded to cover the expense of its operation:
In the UK, when incident detection and automatic signalling were being added to an existing inter-urban traffic management system, a cost benefit analysis was undertaken based on accident and delay saving benefits - to produce a generic business case. Sensitivity testing of the cost/benefit model gave a traffic flow figure for motorways above which, the probability of accidents meant that the accident and delay saving benefits exceeded the cost of installing incident detection. In this case, the criteria derived to justify adding incident detection to a section of motorway, came in the form of a traffic flow-rate per lane of motorway. This standard of provision prescribed that all motorways with more than 20,000 vehicles per lane per day justified the addition of incident detection. A study ten years after the first installation confirmed that the criteria being applied – and the generic business case – were correct.