Highways Agency - Safe roads, Reliable journeys, Informed travellers

Related pages

• Traffic Incident Management Bulletin

July 2007

Why is location so important?

When travelling on the Highways Agency network knowing which junction to exit at is often dependent upon sufficient location information. Fortunately for incident managers there are other methods of defining a precise location between junctions.

The first 60 minutes after a significant injury are the most critical. This is the golden hour where the faster medical intervention can reach a casualty the less likely that person's condition will deteriorate. Not all incidents involve saving life but they are still time critical as rapid attendance at the scene allows normality to be restored promptly. 

Accurate location information allows decisions to be taken remotely. The location of the incident is key when deploying resources. E.g. from a HA Service Provider viewpoint if a spillage location is accurately known the outfall could be identified remotely. This speeds up the environmental response and better protects the ecology of the area.

After the incident has cleared there are still important functions that rely on accurate location information.  

• Damage to Crown Property, such as safety barriers, is claimed back from the insurers of those involved. Inaccurate location information causes difficulties during this process.
• Road safety schemes are prioritised, in part, using analysis identifying accident cluster sites. If locations are not accurately recorded then incident clusters may not be apparent.

How can you identify where you are?

Determining locations on the HA's network can be difficult in the occasional featureless landscape it passes through. There are various network referencing systems available:

• Road name / number is widely understood and available on road maps. Local names for roads could cause confusion for those less familiar with the area.
• Junctions names / numbers are commonly used although the names are not typically printed on maps nor signed on site. 
• Marker posts are present on all motorways and certain all purpose trunk roads. These are numbered white posts every 100m with certain routes benefiting from the driver location signs every 500m. Used in isolation they rely on local knowledge to determine where along the route the location is. Emergency telephones, VMS and electrical cabinet reference numbers are related to the marker post system on motorways.

A Driver Location Sign next to a standard distance marker post

• Lamp post numbers are not necessarily related to marker posts so although used there are other more transferable systems available.
• Direction of travel when reported by the public may be as simple as "towards Birmingham". Typically this is translated into north, south, east or westbound. In addition, there is a system of A and B carriageways linked to the marker post system. The A carriageway has increasing marker post number in the direction of travel. Finally for the M60 and M25 there is clockwise and anticlockwise.
• Slip roads are the entry and exit points of the network. There can be confusion between the access and exit slip. For example, the exit slip to a service area provides access to the facility. The A and B notation continues with J, K, L and M slip roads.

Illustration of the slip road letter notation system

• Link roads typically join two major routes. These can be referred to by origin and destination be that towns or routes. For example, at the intersection of the M6 and M62 near Manchester the M6 south to M62 east link road is also known as the Preston to Manchester link road. For simple link roads the J, K, L and M notation applies.
• Ordnance Survey Grid Reference (OSGR) is now being used for incident management. Prior to GPS technology becoming available there was no quick and accurate way of determining OSGR on site. Vehicle tracking allows a control room to pin point the vehicles on scene. Beware that vehicles could be some distance from the scene if, for example, manning closures.
• CHART sections are used primarily by the maintenance community for referencing routine inspections. It is a well established maintenance system but is not of use in incident management.
• Finally where routes have more than one lane in each direction there are various ways the lanes can be described. Informally, there is the slow, middle and fast lane although this gets confused for routes with more than 3 lanes. Nearside (left), centre and offside (right) suffers the same problems. Numbering lanes from left to right is widely accepted. The M42 Advance Traffic Management uses "Lane below sign 1, 2, 3 or 4" terminology as the hardshoulder, when open, becomes lane 1.

Illustration of the motorway lane numbering system

Understanding location information

Having accurate information is only of benefit if all involved understand it. Below are some concepts which may be of use:

• Use more than one referencing system. For example M6 Northbound (A Carriageway) Marker post 123/4 between junctions X and Y.
• Ask the person receiving the information to repeat the location to ensure they understand and have recorded it accurately. It is easy to accidentally transpose numbers.
• Once the first resource from any organisation arrives on scene the control room could confirm the location.
• Don't be afraid to ask for clarification if unsure of the location.
• Information at the time of incident notification is important. If possible try to obtain  a marker post number.
• Do not make assumptions such as the incident is close to the Emergency Telephone Box used to report it.