TTRSA undertakes both Automatic Traffic Count (ATC) based speed surveys using our MetroCount Vehicle Classifiers, and also radar based speed surveys for short survey periods. TTRSA always work with best practice guidelines set out by relevant highway authorities and adopt the method for the speed survey which best meets your data/analysis needs.
Speed surveys are often required by local authorities and other planning bodies where the sight lines and sight distances (also referred to vision lines and vision distances) set out in Transport Infrastructure Ireland (TII) guidance, Development Plan standards or the Design Manual for Urban Roads and Streets (DMURS) are either not possible or not desirable.
The TII standard DN-GEO-03060 (Geometric Design of Junctions) now indicates that the design speed of the major road at a junction or access should be the traffic speed on the major road. This traffic speed is usually accepted as the 85th percentile speed of light vehicles on the major road recorded through a speed surveys.
Speed surveys are also useful to help designers determine the appropriate provision of infrastructure, such as whether to provide an on-road or off-road cycle track, and are essential for monitoring the effectiveness of the implementation of traffic calming and other safety schemes.