Singapore legislation
Regulation 22
of Civil Aviation Authority of Singapore (Changi Airport) By-laws 2009
Regulation 22
Vehicle not equipped with 2-way radio communication system
Subregulation 1
Except as otherwise permitted by the airport licensee, no person shall drive on any runway or taxiway a vehicle which is not equipped with a 2-way radio communication system.
Subregulation 2
Where permission has been granted for a vehicle which is not equipped with a 2-way radio communication system to be driven on a runway or taxiway, the driver of the vehicle shall comply with the following light signals directed at the vehicle on or approaching the runway or taxiway:
a continuous green light indicating that the vehicle may proceed on the runway or taxiway;
a continuous red light indicating that the vehicle is temporarily prohibited from proceeding on the runway or taxiway and the driver shall stop the vehicle immediately;
an intermittent red light indicating that the vehicle must keep clear of the runway or taxiway immediately;
an intermittent green light indicating that the vehicle which has earlier been ordered to keep clear of the runway or taxiway may return to the runway or taxiway; and
an intermittent white light indicating that the driver must drive the vehicle out of the runway or taxiway and out of the movement area immediately.