Definition of red x compliance
Case reference FOI2024/01146
Received 20 September 2024
Published 13 December 2024
Request
Response
We confirm that there is no report showing further evidence on Red X compliance using the CMT tool, other than the information we had shared with you in our previous response (ref FOI2024/787).
Q1: What is the National Highways working definition of red x ‘compliance’?
It has been an offence for more than two decades to drive in a lane closed by a Red X signal.
Red X compliance is the action taken by drivers to comply with a Red X signal instructing that they must not enter, or proceed in, a closed lane.
Red X compliance is measured as the percentage of all vehicles, across all lanes, where a driver has chosen to comply with a Red X signal that is set for a lane closure, and has passed the closure in an open lane.
More information about Red X is available on our website
Q2: what is actually being measured when NH is measuring ‘compliance’?
Compliance is measured by counting all vehicles driving over sensors embedded in the road at regular intervals along the carriageway and is also linked to the Red X signal settings.
Non-compliance is defined as any vehicles who enter, or proceed in any part of a closed lane when a Red X signal is displayed.
As an example, the calculation to determine the percentage of compliance for a Lane 1 closure at a three-lane location would be as follows;
Red X % compliance =
((V in Lane 2 + V in Lane 3) / (V in Lane 1 + V in Lane 2 + V in Lane 3) x 100
In this example V represents the total number of vehicles counted in each lane by the sensors in the carriageway.
Documents
This is National Highways' response to a freedom of information (FOI) or environmental information regulations (EIR) request.
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