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Incident Management Tactics Can Change
December 2007
Following the article in the September 2007 bulletin on releasing trapped traffic the South West RCC have contacted the TIM Bulletin with some first hand experience. This article aims to share their experience for everyone to benefit from.
Real Life Experience
An incident occurred on the M5 southbound carriageway which required trapped traffic to be released. The chosen method to release the traffic was to turn the traffic around and allow vehicles to travel north on the southbound carriageway and leave at the previous junction.
This specific incident on the M5 resulted in both slip roads being used to turn traffic at different times. Initially the southbound access slip was used to take turned traffic off the motorway but due to the roundabout layout and traffic signals the operation was not working well. At that stage the decision was made to change tactics and use the exit slip road, this freed up a resource as only one patrol was required as opposed to two.
The necessary traffic management was installed to use the exit slip road merging traffic into the main line flow exiting the M5. Once in place this gave better results, however it does not mean that the exit slip road should be used at every location. Each situation should be assessed and if necessary the tactics changed if the operation is not working.
In this case the exit slip road was 2 lanes wide and therefore lent itself well to the use of rearward relief. The traffic management layout employed here allowed for the traffic being diverted off the motorway and the traffic being turned around to merge prior to reaching the roundabout. This seemed to work well. You can examine the layout used. Please note that this is not a traffic management drawing showing signing and coning in its precise locations but does show how the layout directed the traffic.
Key points highlighted during this incident.
- The situation must be carefully assessed to determine tactics considering:
- Layout of main line, slip road and roundabout / junction
- Available resources
- Safety of staff and travelling public
- Speed of implementation
- Number and type of vehicles to be turned
- If current tactics are not working then reassess the situation and change tactics if deemed worthwhile.
Feedback from the previous article
The September article did prompt some discussion via the TIM Bulletin email address regarding which slip road is best to use when implementing a rearward relief operation of this type. Following consultation with the Traffic Officer Manual and other guidance it is clear that there is no definitive answer. The advice provided by the documentation is that:
“Local junction layouts will determine whether the turned round traffic should be removed via the access slip-on or at the point where other traffic is being diverted from the carriageway”
It is important therefore to assess the junction layout along with traffic conditions and expected duration to determine which slip road to use. Remember the primary aim of the operation is to release the trapped traffic on to the diversion route as quickly and safely as possible. Ideally this operation will result in minimal disruption to the main line flow of traffic exiting at the junction.
Has this article been worthwhile reading? Why not take a moment to send us your comments, thoughts or questions. Please e-mail TIMbulletin@highways.gsi.gov.uk.
