Heavy oil

1) Correct term for describing diesel oil (as opposed to light oil - ie paraffin, etc). Diesel engines are correctly referred to as heavy oil engines.

Heavy locomotive

1) Heavy vehicle legally defined as being one which is not constructed to carry a load and with an ulw exceeding 11,690 kg -namely, a pulling vehicle primarily used in heavy haulage (see above).

Heavy haulage

1) Common term for business of hauling exceptionally heavy or large items (ie abnormal loads frequently outside scope of the C&U regulations and within Special Types General Order). Renowned industry sector for large, powerful and often specially built tractors and trailers.

Health and Safety at Work, etc Act of 1974

1) Intended to ensure the health and safety of persons at work. Sets out responsibilities and obligations of both employers and employees and gives powers to inspectors to issue prohibition notices to stop unsafe practices.

HD

1) Home delivery. System whereby retailers will deliver goods to the customer's home. Also includes delivery of goods ordered via the Internet for home delivery.

HC

1) Hydrocarbon. Scientific designation for this product of vehicle exhaust emissions. A so-called 'greenhouse gas' contributing to global warming. See also CO, C0₂, NOx and PM.