Dynamically vary auto-generated Variable Speed Limits (VSLs)

Highways England is currently undertaking a programme of improvements to Variable Speed Limits (VSLs) on the motorway and all-purpose trunk road network. This is to improve the appropriateness of both mandatory and advisory VSLs, based on safety and customer insight.

There are occasions when our algorithms and signal sequencing rules automatically set default variable speed limits that are thought to be overly restrictive. For the most part, these algorithms set appropriate speed limits to suit most situations, but there are some situations where it is believed that being able to manually increase the speed limits would be of benefit to our customers.

For example, whenever a Red X is set, an associated speed limit of 40mph is also set. There may be some situations where a 50mph may be suitable, but Regional Operation Centre (ROCs) Operators are unable to apply human intervention; they cannot overrule default system settings to safely raise a speed limit. At present operators are only able to manually decrease auto generated variable speed limits.

Highways England is seeking to procure technical consultancy services that will explore and assess the feasibility of safely allowing Operators within the ROCs to dynamically alter the auto-generated speed restrictions that're set by the pre-programmed signalling algorithms and system software rules.