Highways Agency

Winter maintenance

Weather and Road Surface Condition

8.1 In the preparation of this report, weather data has been obtained from the Highways Agency's automated weather station on the M62 Motorway at High Eggborough (located approximately 3.2 kilometres (2 miles) to the west of the material location) for 28 February 2001.

8.2 This data shows that, between 0000 GMT and 0620 GMT on 28 February 2001, i.e. for the period encompassing approximately six hours preceding the material accident, the air temperature fell relatively consistently from +2.4°C at 0000 GMT to +0.5°C at 0620 GMT.

8.3 The data indicates that light rain was falling at the station during the periods 0020 GMT to 0120 GMT, 0240 GMT to 0300 GMT and 0420 GMT to 0720 GMT.

8.4 There are two road surface temperature sensors at this station. The road surface temperature at one of these sensors fell steadily from +3.5°C at 0000 GMT to +2.1°C at 0600 GMT and then relatively rapidly decreased to +1.6°C at 0620 GMT. The surface temperature recorded by the other sensor at this site fell more erratically, reaching a minimum of +0.8°C at 0520 GMT and then rising to +1.2°C again by 0620 GMT.

8.5 The sensing equipment is also capable of measuring road condition at the surface sensors, i.e. whether the road was dry, wet, icy or salted (although the method utilised to determine salinity levels cannot record the presence of salt on a dry surface and commonly underestimates the amount of salt present at other times). Both surface sensors at High Eggborough indicate that salt was present on the material carriageway during this period

8.6 In the preparation of this report, data from the weather stations on the A1(T) at Barnsdale Bar and the M18 at Hatfield has also been obtained. These stations are located in the general area of interest but further away from Little Heck Bridge than High Eggborough.

8.7 These data indicate:

• For Barnsdale Bar: lowest air temperature +0.3°C at 0600 GMT; light rain recorded at 0100 GMT, 0500 GMT, 0600 GMT and 0700 GMT; lowest road surface temperature +0.8°C at 0700 GMT;
• For Hatfield: lowest air temperature +0.7°C at 0700 GMT; light rain recorded at 0100 GMT and 0300 GMT; lowest road surface temperature +1.4°C at 0600 GMT.

8.8 Both these stations recorded the presence of residual salt during this period.

8.9 TRL has been informed that, at 0725 GMT on 28 February 2001, i.e. some 70 minutes after the accident involving Mr Hart, the road surface condition at Little Heck Bridge was found by a WSP engineer to be damp and that no snow was present.

8.10 On the basis of all of the information discussed above, it appears unlikely that the surface of the M62 Motorway at Little Heck Bridge was adversely affected by ice or snow at the time of Mr Hart's accident.

8.11 However, in view of the fact that the cause of the vehicle leaving the carriageway is currently unknown and it is possible that the Police investigations will comment on road surface condition, the following sections discuss the winter maintenance procedures adopted by the maintaining engineers and provide opinion regarding their adequacy.

Highway Winter Maintenance Methodology

8.12 The primary method of preventing the formation of frost and ice on road surfaces during freezing periods is to spread salt from purpose built vehicles. These are equipped with a hopper and a spreader mechanism, which can regulate both the rate of spread and the spread pattern so that the whole of the road surface can be treated with the correct amount of salt.

8.13 Salt in solution freezes at a lower temperature than water alone and if spread before the onset of freezing conditions can be effective in preventing ice from forming on road surfaces at temperatures down to below -10°C.

8.14 However, salt is only effective in this role if it can form a solution with the water on the road surface. If this water has already frozen before the salt is applied the salt is much less effective in combating the slippery conditions. Occasionally therefore, sand is included with the salt as this, in conjunction with the action of vehicle tyres can aid both grip and the break up of existing ice.

8.15 Due to various reasons, including the blocking of drainage channels and the problems it causes after the ice hazard has passed, grit of a particle size greater than sand is no longer used on UK roads for this purpose. However the generic term "gritting" is often used to describe what is actually "pre-salting" or "precautionary salting", i.e. spreading salt before the onset of ice and frost formation. This is the primary method of dealing with freezing conditions on roads across the UK.

8.16 Depending upon whether precipitation is forecast, typical rates of spread of salt when pre-salting range from 10 to 20 grammes per square metre (g/m2 ).

8.17 Post-salting applications, i.e. those undertaken in order to aid the break up and removal of snow and ice from the carriageway surface once it has formed, is less efficient and typical rates of spread when post-salting are between 20 to 40 g/m2.

Winter Maintenance Standards

8.18 The document that details the standards to which the pertinent section of the M62 Motorway is to be maintained during winter conditions, is Part 3 of Volume 2 of the Trunk Road Maintenance Manual (1996).

8.19 This document includes a Statement of Service in respect to the winter maintenance of trunk roads and motorways, stating: "The Highways Agency aims to provide a winter maintenance service which, as far as possible, allows the safe movement of traffic on motorways and all-purpose trunk roads (APTRs) in England, and keeps delays and accidents caused by adverse weather to a minimum".

8.20 The TRMM goes on to state that Maintaining Agents are required to undertake the operational management of the winter maintenance service on behalf of the Highways Agency.

8.21 For operational purposes, the TRMM divides the winter season into three periods:

1. (i) High, i.e. the months of December, January and February, when severe conditions are described as probable;
2. (ii) Low, i.e. November and March, when severe conditions may occur.
3. (iii) Marginal, i.e. October and April, when severe conditions would not be expected.

8.22 It can be seen from this that the date of the material accident, 28 February 2001, is just within the "High" period.

8.23 It is also stated that treatment routes and shift arrangements must be organised to allow defined standards of Response and Treatment Times to be achieved.

8.24 The Response Time is defined as the time taken from the decision to begin treatment until the winter maintenance vehicles are loaded, manned and ready to leave the compound.

8.25 The Treatment Time is defined as the time taken from leaving the compound, in order to begin the treatment of the trunk roads for which the Maintaining Agent is responsible, through to completion of the treatment.

8.26 The TRMM stresses that precautionary treatment of motorways and other trunk roads shall be undertaken within a maximum Response Time of 1 hour and a maximum Treatment Time of 2 hours. Therefore, the winter maintenance system developed must be capable of achieving a Total Treatment Time of 3 hours, when necessary. The Total Treatment Time being defined as the period between taking a decision to undertake an immediate precautionary salting operation and the time when the salting routes have been completed.

8.27 Anticipating ice forming or snow settling on the road surface, and then reacting correctly, will depend upon a mixture of local knowledge and experience, good weather forecasts and an awareness of the current condition of the road (i.e. whether it is wet or dry and/or whether any residual salt from previous treatments is sufficient to mitigate against anticipated weather conditions). The TRMM recommends that Maintaining Agents make full use of specialised road weather forecasting services offered by meteorological organisations for this purpose.

8.28 The document contains the following guidance:

"A decision to treat [salt the road] will depend upon many factors but if road surface temperatures are predicted to fall below plus 1°C a precautionary treatment should normally take place unless:

(a) no moisture is on or is expected to be on the road; or
(b) there is sufficient residual salt on the road to deal with the expected conditions "

8.29 The TRMM warns that elevated sections of road, including bridges, and sections lying in low ground or where the topography channels wind-borne cold air, are more prone to freezing and may need special attention.

8.30 For precautionary salting operations, the TRMM recommends that barn stored salt should be spread at 10 g/m² and salt stored in the open at up to 20 g/m². This rate should be increased to between 20 and 40 g/m² if freezing conditions are expected after rain, or continuous snowfall is forecast.

8.31 For post salting operations (i.e. when ice or snow has already formed), the TRMM recommends that salt be spread at up to 40 g/m² to ensure a rapid melt. Post salting treatments can be undertaken in association with physical ploughing.

8.32 The TRMM recognises that road conditions can change very quickly over relatively short distances and states that this stresses the importance of effective liaison between the Maintaining Agent, Contractor, the weather forecast provider, the Police and other emergency services, the media, public transport operators and various road user groups. Maintaining Agents are also encouraged to actively liaise with the local Police patrols regarding road conditions.

The System Of Winter Maintenance Operated By The Maintaining Agent

8.33 WSP's "Winter Maintenance and Other Emergencies" Plan, dated November 2000 was in effect at the time and location of Mr Hart's accident.

8.34 The introduction to this Plan states:

"This document has been prepared as a guide and describes the Winter Maintenance Procedures for the Area 16 Motorway and Trunk Road Network and has been compiled in conjunction with the "Trunk Road Maintenance Manual: Volume 2, Part 3 Winter Maintenance Code" published by the Highways Agency."

8.35 The Plan also covers the call-out procedure for all other types of highway emergency, i.e. it does not just concern winter maintenance activities.

8.36 The Plan states that WSP have operational staff at three motorway compound offices (known as Sub-Area Control Offices), based at Tingley, Aston and West Cowick. Each office is responsible for operational and maintenance functions for their particular sub-area.

8.37 It is stated that each of the three sub-area offices possesses a Winter Duty Officer and a named Deputy, who operate in the role during normal hours (0800 to 1700 hrs, Monday to Friday). Outside of normal hours, a Duty Standby Officer assumes responsibility for receiving any weather forecast updates and taking any necessary out-of-hours winter maintenance decisions.

8.38 The Plan states that Carillion are responsible for effecting winter maintenance operations (i.e. implementing the instructions of WSP).

8.39 A total of nine operational compounds are used across the area by WSP, including the location of the Sub-Area Offices at Aston, Tingley and West Cowick.

8.40 It is stated that Carillion "organises" salting and ploughing from each of the nine compounds using pre-determined salting routes and following instructions issued by WSP.

8.41 Of winter maintenance labour, the Plan states that necessary cover is obtained by utilising operatives on Standby (at home or at the compound), or by Normal or Continuous Shifts.

8.42 The Plan clearly states that "only experienced personnel will be employed outside normal shifts".

8.43 The following shift definitions are provided:

• Normal - On duty based at the compound during normal working hours;
• Continuous - On duty based at the compound 24 hours;
• Standby - Personnel available at the compound no more than one hour after being called out from elsewhere or from home;
• Call Out - Off duty personnel available for duty as demand arises.

8.44 The above is consistent with requirements of the TRMM.

8.45 The Plan clearly indicates that WSP operate to a one hour Response Time and a two hour Treatment Time, which is in accordance with the TRMM.

8.46 The Plan states that winter weather forecasts are received daily at the Sub-Area Offices (at Aston, Tingley and West Cowick) between 1300 and 1430 GMT, via the Vaisala TMI Computer Bureau, based in Birmingham.

8.47 It is understood that copies of forecasts received are held at each Sub-Area Office. The Plan states that site specific forecasts are received for five of the area's 11 automated weather/ice prediction station sites. It is acknowledged that forecast updates may be issued or received at any time.

8.48 However, it is also stated that, in the absence of a forecast for any reason, precautionary salting would take place when temperatures reached +1°C and were falling, provided that prevailing humidity, residual salt levels and cloud cover were consistent with such a decision. This is consistent with the TRMM.

8.49 With respect to the rate of spread of salt to be adopted, the Plan states:

"For precautionary salting, treatments shall be carried out at the minimum rate of 10 g/m sq. These rates may be increased up to 20 g/m sq, according to the amount of humidity expected and the carriageway construction.

If ice has formed on the road surface salt should be spread at the rate of up to 40 g/m sq depending upon the amount of ice to be removed and the temperature. On receipt of a forecast of snow, pre-salting should be carried out at 20-40 g/m sq according to the anticipated severity of the snowfall"

8.50 The above rates of spread are consistent with those contained within the TRMM.

8.51 The Plan recognises the operational problems associated with undertaking precautionary salting operations in peak hour traffic conditions, stating that:

"Generally, morning salting runs must be completed by 07:00hrs and evening salting should not commence until 20:00hrs"

8.52 The Plan states that, once a decision has been reached to undertake a precautionary salting operation, WSP will notify adjoining Maintaining Agents by facsimile during working hours. A specimen facsimile notification is provided within the Plan.

8.53 The Plan states that Highways Agency owned salting vehicles (comprising of front line operational vehicles and reserve vehicles) have been allocated to the various compounds across the area.

8.54 It appears that all salt used for winter maintenance on the M62 Motorway is stored undercover.

8.55 The Plan also contains various maps and schedules showing salting routes, fleet profiles and the location of automatic weather / ice prediction out stations and sub-area compounds. With respect to the westbound carriageway of the M62 Motorway at Little Heck Bridge, the Plan contains the following information:

• This location lies within the Humberside Sub-Area, which is administered from West Cowick Maintenance Compound/Sub-Area Office;
• It is included within Salting Route R20, which is serviced from the West Cowick Maintenance Compound. The route is given the radio call sign "Cowick Gritter 1" and is serviced by salting vehicle index number L602 GYP. The schedule for the route indicates that the route should take 1 hour to complete, with 48 minutes of this constituting the actual treatment duration. Route R20 is stated to have a total length of 62.6 km (comprising 37.8 km of salting and 24.8 km of dead running). The material location is treated in the early stages of route R20;
• The maintenance compound at West Cowick has a capacity of 6,000 tonnes of rock salt and has a dedicated fleet of four salting vehicles (three front line vehicles and one spare), a loading shovel and a snowblower;

8.56 The Winter Maintenance Plan prepared by WSP is relatively detailed and is considered to describe a highway maintenance system that is capable of meeting the requirements of the TRMM Volume 2 Part 3 (1996), as well as generally following good and recommended UK practice.

Winter Maintenance Operations Undertaken Around The Material Time And Location

8.57 In the preparation of this report, various winter maintenance records have been provided by WSP and Carillion.

8.58 These include a copy of the WSP winter maintenance Standby Rota for the period October 2000 to April 2001. The rota indicates that Paul Fisher was the Duty Standby Officer, and David Hotchkiss the secondary contact, for the WSP Humberside region (West Cowick Sub-Area Office) for the week commencing 27 February 2001.

8.59 In general terms, the period between 22 February 2001 and 4 March 2001 saw a prolonged period of cold weather, characterised by often frosty, icy and snowy conditions.

8.60 The morning summary forecast for the WSP Humberside Region issued at 0621 GMT on 27 February 2001. This stated that 27 February 2001 would be a "mostly cloudy day with occasional light rain and sleet". Of the night 27/28 February 2001, the morning summary stated:

"Overnight more persistent precipitation will spread from the north falling as wet snow or sleet at times. Accumulations of up to 2 cm are possible with temperatures hovering around zero celsius."

8.61 The morning summary also predicted hazards relating to low road surface temperatures, ice and snow.

8.62 The 24-hour text forecast issued for WSP at 1434 GMT on 27 February 2001 referred to the period 1200 GMT on 27 February 2001 to 1200 GMT on 28 February 2001 and predicted ice, snow but no hoar frost with a high level of confidence, and fog with a low level of confidence. The minimum predicted air temperature was -1°C for the period 0000 GMT on 28 February 2001 until 1000 GMT on 28 February 2001. The minimum predicted road surface temperature was -2°C in areas where there would be lying snow, with the prediction being considered valid throughout the 24 hour forecast period.

8.63 The above forecast also included the following text with respect to road state: "A covering of snow expected during today [27 February 2001]. Further snow expected overnight, likely to persist in places tomorrow morning [28 February 2001]"

8.64 The forecast also stated that 10 to 30 mm of snow was to be expected in the WSP Humberside Region during the night of 27/28 February 2001 and the morning of 28 February 2001.

8.65 The forecast concluded with a summary of the weather expected for 27 and 28 February 2001, such that:

• 27 February 2001 (from 1200 GMT): mainly cloudy with outbreaks of sleet and snow;
• Night of 27 / 28 February 2001: cloudy with snow, heavy and persistent at times;
• 28 February 2001 (until 1200 GMT): rather cloudy with sleet and snow gradually clearing away to the south.

8.66 It appears that an evening update to the above 24 hour forecast was issued at 1810 GMT on 27 February 2001. This specifically stated:

"NO MAJOR CHANGES TO THE MIDDAY FORECAST"

8.67 However, the evening update included an amended concluding summary. The amendment concerns the weather conditions at the time of issue of the evening update and stated:

"Sleet or snow showers have now died away. More persistent snow expected towards midnight."

8.68 A forecast graph for the weather station site on the M62 at High Eggborough, was issued at 1811 GMT on 27 February 2001, which referred to the period 0000 GMT on 27 February 2001 to 1200 GMT on 28 February 2001.

8.69 The copy of this graph provided to TRL includes predicted and actually recorded temperatures during this period. Both the predicted and actual temperatures remained above 0°C for the entire period.

8.70 The forecast text issued for High Eggborough at 1811 GMT on 27 February 2001 referred to the period until 1200 GMT on 28 February 2001. The forecast text accompanied the above forecast graph and predicts a minimum air temperature of -1°C and a predicted minimum road surface temperature of -2 °C. The accompanying text stated that the forecast graph issued at 1811 GMT on 27 February 2001 was based on cloudy skies with rain from midnight, turning to sleet or snow for a time and with road surface temperatures expected to dip close to zero degrees Centigrade during any snow falls. Icy roads were predicted after midnight, also during snow falls. Patchy fog was also predicted.

8.71 With respect to the winter maintenance response of WSP to the above series of forecasts, a typed sheet entitled "Incident M62 Westbound between J35 - J34 Little Heck Railway Bridge", prepared by PG Fisher, Area Maintenance Manager (Humberside) and the Duty Standby Officer for the period 0900 GMT on 27 February 2001 to 0900 GMT on 6 March 2001 has been provided to TRL.

8.72 The sheet provides a winter maintenance chronology for the period from 1200 GMT on 27 February 2001 until 1200 GMT on 28 February 2001.

8.73 The entry for 1645 GMT on 27 February 2001 states that a winter maintenance decision was delayed until the evening forecast update was received, as the hazards previously forecast were not anticipated until after midnight.

8.74 This is consistent with the WSP Winter Maintenance Operations facsimile completed for the Humberside Region at West Cowick depot on 27 February 2001, which stated: "Awaiting evening update. Some action will take place but the timing is unknown as yet".

8.75 It is considered that this was a reasonable response, due to the previous forecasts stating that rain would precede any sleet and snow.

8.76 It appears that Mr Fisher next accessed the ice prediction system at his home, via a laptop computer, at 1900 GMT on 27 February 2001. Mr Fisher indicates that, due to there being no significant change to the afternoon forecast and the fact that rain, sleet and snow were forecast for the period after midnight, a winter maintenance operation was instructed to take place at 2200 GMT on 27 February 2001 utilising a rate of spread of salt of 20 g/m². In addition, staff were instructed to remain on Standby at the depot until further notice.

8.77 The above is consistent with a West Cowick depot log, which contains the following entry for 2200 GMT: "GRITTING PROGRAMME IN OPERATION". The log continues with the following entry for 2350 GMT: "ALL MEN IN DEPOTS AND STANDING BY".

8.78 A winter maintenance record completed by R Walker, the salting vehicle driver on Route 20 (i.e. the route including the material location), has also been provided to TRL. This indicates that salting was successfully undertaken on this route, commencing at 2200 GMT on 27 February 2001.

8.79 It is considered that the decision to salt at 2200 GMT on 27 February 2001 was entirely reasonable, given the relatively uncertain timing and form of any precipitation.

8.80 It appears that Mr Fisher next accessed the ice detection system at 0145 GMT on 28 February 2001, again via a laptop computer at his home. Mr Fisher notes that at this time no changes had been made to the forecast for the High Eggborough outstation site.

8.81 It appears that Mr Fisher then contacted the weather forecast provider (Leeds Weather Centre) and was informed that accumulations of snow would be unlikely in the Humberside Region, but that road surface temperatures may dip close to 0°C.

8.82 Mr Fisher indicates that he then telephoned the security office at West Cowick compound at around 0205 GMT on 28 February 2001 and was informed that rain had fallen since the salting operation at 2200 GMT on 27 February 2001. The above appears consistent with data from the High Eggborough weather station, which indicates that light rain was falling at this location between 0020 GMT and 0120 GMT.

8.83 It appears that the incidence of rainfall resulted in Mr Fisher instructing a further salting operation to take place, again utilising a rate of spread of salt of 20g/m².

8.84 However, there is consistent evidence to the effect that Mr Fisher received a telephone call from West Cowick compound security office between 0210 GMT and 0215 GMT, informing him that rain was falling at Broughton at that time. In response to this information it appears that Mr Fisher instructed that the further salting operation be delayed until the rain had ceased and that, if the delay extended beyond an hour, then the men at the depot should be sent home.

8.85 Mr Fisher received a further call from West Cowick security at around 0240 GMT informing him that heavy rain was by then falling at Cowick and Broughton. The data from the High Eggborough weather station appears broadly consistent with this observation, indicating that light rain was falling at the site of the weather station between 0240 GMT and 0300 GMT. It appears that the information from West Cowick depot prompted Mr Fisher to cancel the further salting operation and an instruction was issued to stand down the men at the depot.

8.86 It is considered that this was a reasonable response to the weather conditions being experienced in the region, given that road surface temperatures were predicted to remain above 0°C during the early hours of 28 February 2001.

8.87 Mr Fisher next received a call from West Cowick depot at between 0630 GMT to 0635 GMT (i.e. some 15 minutes after the accident involving Mr Hart), informing him that sleet and/or snow was falling at that time. This appears to be generally consistent with the High Eggborough weather station data, which indicates that light rain was falling at this location between 0420 GMT and 0720 GMT. It appears that no immediate action was taken in response to the information from West Cowick Depot and that Mr Fisher asked to be informed if snow began to settle.

8.88 The morning summary text issued for the WSP Humberside Area (i.e. including the material location) at 0707 GMT on 28 February 2001, i.e. approximately one hour after the material accident, stated that the weather would be "cloudy with occasional rain and perhaps sleet". The lowest recorded road surface temperature in the region was +1.2°C at Elsham Wold at 0600 GMT, i.e. some 15 minutes prior to the material accident.

8.89 The typed sheet prepared by Mr Fisher indicates that B Wood, a senior supervisor with WSP, reported from the scene of the material accident at 0725 GMT on 28 February 2001, i.e. some 70 minutes after it had occurred. Mr Fisher records that the road conditions were reported as "damp" and that there was "no evidence of snow". This record is considered consistent with the data obtained from the High Eggborough weather station around the material time.