Article 158(1) of Bahrain's Traffic Law Implementing Regulation allows a length concession from the free end for vehicles designed for certain special uses, such as carrying heavy machinery. How is that concession calculated?

1. A flat additional two metres for any special-use vehicle
2. An increase of 70 per cent of the distance between the two axles; where there are three or more axles the distance is measured from the centre of the front axle to the middle of the rear axles
3. Double the standard length limit for the configuration
4. No concession exists; the standard limits are absolute