HB Loads

HB Load files were omitted from the Archie-M 2.5.1 release as they are obsolete. We have occasional requests for these loads, so we have made them available to download here. 

CS454 states (in 2.17.1 note 3):

The HB load models for abnormal traffic loading that were previously defined in BD 21 (withdrawn) for design are included in Appendix C for reference and for exceptional cases where an HB assessment is required by the Overseeing Organisation.

HB loadings are completely unrepresentative of anything the bridges are likely to see now, and if a client demands these you should be clear about why, and ensure they understand that they tell them nothing about capacity in the face of modern loads. There are real risks in using standard loads that are not representative of real traffic. 

The original HB vehicle is the trailer shown below with power provided by traction engines (photo (c) Peter Jewell, licensed under CC BY-SA 3.0). A rigid trailer, towed behind a traction engine. Solid rubber tyres on cast iron wheels with the wheels at 3ft centres and applying a patch which was something like 13" wide by 3" - yes, that's 75mm front to back. 

The next iteration had pneumatic tyres and rather more articulation. This is the one which featured as the HB vehicle through to metrication of the codes. It was available as a girder trailer, allowing a wide range of lengths between bogies. The 3 feet (0.92m) between wheels and 6 feet (1.83m) between axles remained normal.

When the codes were metricated these vehicles were no longer in use, so the load pattern was purely representative and it was thought appropriate to just swap the 3 foot and 6 foot measurements for 1 m and 2 m.