The following is an e-mail below from a member, reproduced with permission:
The definition of ‘practicable’ was tested in “Richmond upon Thames London Borough Council v. Express Ltd (2003)”.
Under the Greater London (Restriction of Goods Vehicles) Traffic Order 1985, it is required that “the vehicle minimises the use of restricted roads. To this end, the applicant and driver of the vehicle shall ensure that the vehicle [… ] (b) takes the shortest practicable route […]”
The case against Express Ltd for breach of this condition went to appeal on the interpretation of the word ‘practicable’.
It was contended that “The justices should consider the word ‘practicable’ and the Oxford English Dictionary definitions: (i) able to put into practice; able to be effected; accomplished; or done; feasible; (ii) of a road, passage, etc; able to be used or traversed”.
In judgement it was held that “The word ‘practicable’ in context, it is clear, means ‘physically practicable’.” The judges found themselves unable to consider other ‘practical’ matters (such as the additional congestion, noise and pollution caused by taking the alternative route) for the purposes of the condition.
“Case remitted to justices with direction to convict.”
IMHO, for the purposes of interpreting the Highway code, with respect to either “Use cycle routes when practicable.” or “wherever possible”, “the discretion of each cyclist to decide whether or not it is indeed possible” would be limited to an assessment of physical traversability.
For an appropriate degree of discretion with respect to safety, we require something akin to the qualifying definitions used between 1954 and 1987:
1946: “If there is a cycle track – use it.”
1954: “If there is an adequate cycle track, use it.”
1968: “If there is an adequate cycle path beside the road, ride on it.”
1978: “If there is a suitable cycle path, ride on it.”