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ORIGINAL VERSIONROAD MANAGEMENT SYSTEM IN ADVERSE WEATHERCONDITIONS: FOG AND WINDXXVII ROAD WORLD CONGRESPRAGA, CZECH REPUBLIC, 02-06 OCTOBER 2023
A. Blanco Bergareche, R. Martínez Rodríguez, Subdirección de Gestión de la Movilidad y
Tecnología, DGT (Dirección General de Tráfico)abergareche@dgt.es ramiromr@dgt.es
L. Rey Ramos, G. Leiro García, G. Ruggiero Pelay, Departamento de Gestión de laMovilidad, Antea Grouplaurarey@anteagroup.es gemaleiro@anteagroup.es gabrielaruggiero@anteagroup.es
ABSTRACTThe A-8 Cantabrian motorway (hereinafter A-8) in the area of Alto del Fiouco, between km
545+500 and 549+500, presents particular weather conditions with episodes of dense fog
combined with strong winds which make driving difficult, because of this, sometimes, it isnecessary to close the motorway and divert vehicles to the N-634 road, as it is not possible
to guarantee the minimum safety conditions for its use.
For this reason, the Directorate General of Traffic (hereinafter DGT) has establishedprotocols for managing the road when there are adverse weather conditions of fog and wind,and has installed a series of ITS equipment that has made it possible to manage therestrictions more efficiently and safely, also increasing the number of hours that the
motorway is operational.
The system installed allows the automatic closure and detour of vehicles by using thefollowing ITS devices: weather stations to detect visibility values and wind speed anddirection, Variable Message Signs, red light cameras to control compliance with restrictions
and traffic lights and beacons to inform the user. In addition, presence detector beacons
have been installed, which allow greater safety in foggy conditions, warning of the presenceof vehicles on the road.
This article describes the protocols applied, the equipment systems installed to comply withthese protocols and the effect these systems have had on the operability and safety of thisaffected section of the A-8.

1

DESCRIPTION

The A-8 is a two-lane road running almost parallel to the coast of the Cantabrian Sea,
connecting the Autonomous Communities of the Basque Country, Cantabria, Asturias andGalicia. The A-8, with a total length of approximately 486 km, begins in Bilbao, at the junctionof the AP-8 with the AP-68, and ends in Baamonde (Province of Lugo) where it joins the A6 motorway.

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Figure 1 – Route of the Cantabrian motorway (A-8). Source: Wikimedia maps
In February 2014, the Mondoñedo-Lindín and Lindín-Careira sections of the A-8 wereinaugurated, which pass through the municipalities of Lourenzá, Mondoñedo, Abadín andPastoriza. Both sections are 15.9 km long and run southeast of the old national road N-634.
The infrastructure has two carriageways, each with two 3.5 m wide lanes, outer verges of
2.5 m and inner verges of 1.0 m, separated by a median between 2.0 and 6.0 m wide,
depending on the section.
These sections of motorway have required important and complex engineering works, as
they run through uneven and geotechnically very complicated terrain. As a result, major
cuttings, surface and deep drainage works, retaining walls on the mid-slope sections and alarge number of structures of various types have been carried out. Among these, the O
Fiouco viaduct stands out.
The section of the A-8 under study corresponds to the Alto de O Fiouco, which is between
KP 545+500 and 549+500, runs at an altitude of 700 m and has two main problems: windand lack of visibility due to fog.
Since it was put into service in February 2014, there have been numerous episodes ofintense fog which have caused significant multiple collisions. On 26 July 2014, the mostserious multiple collision occurred, involving a total of 39 cars and lorries, resulting in 1
fatality and more than 40 injuries of varying severity. Since then, specific measures havebeen implemented to mitigate the effects of fog on this section of the A-8, which aredescribed in this article.

2

OBJECTIVES

The main objectives of the initiative are listed below:

To provide a coordinated framework for action in the event of a traffic situation due
to adverse weather conditions.
To inform road users about weather conditions on the road and the necessary
adjustment of speed or detour to an alternative route.

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 Contribute to road safety in adverse weather situations associated with fog and highwinds.
 Contribute to optimal traffic management: information on adverse weather episodes
on the roads allows Traffic Management Centres to make decisions quickly andefficiently.
3

TECHNICAL CHALENGES

3.1

PROTOCOL DEFINITION

Based on the meteorological records of the visibility distance in the presence of fog and theintensity and direction of the wind in the area, action protocols were defined on this stretchof motorway to adapt the speed of vehicles according to the weather conditions at the time.
The protocols for fog and wind, described below, establish four levels which, following thecolour code of the traffic lights, increase the restrictions as road conditions worsen.
3.1.1 Protocol in windy conditions
In the process of drawing up the protocol for action in the event of wind, the analysis ofmeteorological records in the area was complemented with exhaustive benchmarking todetermine the thresholds to be implemented based on success cases. [2-6]
The wind protocol has a first level (green level) of recommendation of moderation of traffic
speed when wind speed exceeds 30km/h, and two levels of reducing speed limit to 80km/h(yellow level), if wind speed exceeds 50km/h, and to 60km/h (red level), if wind speed
exceeds 80km/h. The fourth level corresponds to the closure of the motorway when the windspeed exceeds 130km/h.

Figure 2 – protocol in windy conditions

3.1.2 Protocol in the presence of fog
In order to define the protocol for action in the event of fog, initially, in addition to analysing
the visibility in the area, the provisions of Regulation 3.1-IC Layout of the Highway Instruction("BOE" of 2 February 2000)[1] were taken into account in relation to visibility and braking
distance, thus obtaining the visibility value of 40 metres for the closure of the motorway.
Subsequently, with the installation of the presence-detecting beacons described in section
3.3, and the consequent improvement in traffic conditions, the threshold for closing the
motorway was adjusted to a visibility of less than 30 metres.

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Therefore, the current fog protocol, like the wind protocol, has four levels: one ofrecommendation and three of restriction. The first level (green) is applicable when thevisibility distance is between 150 and 250 metres, where it is recommended to moderate thespeed and the use of dipped headlights is mandatory in conditions of reduced visibility. In
the second level (yellow), with a visibility between 75 and 150 metres, the speed limit isrestricted to 80 km/h. At the third level (red), with visibility between 30 and 75 metres, thespeed limit is 60 km/h and, finally, when visibility is less than 30 metres (black), the motorway
is closed and the automated detour of vehicles to an alternative route is activated.

Figure 3 – Protocol in the presence of fog

3.2

AUTOMATED DETOUR AND PROTOCOL IN FOG AND WINDY CONDITIONS

Initially, the detour due to the presence of fog/wind was carried out manually, so that eachactivation of the detour was notified to the Piedrafita Tunnel Control Centre, which in turnnotified the Integral Maintenance of the Mondoñedo area (Lugo) under the Ministry ofTransport, Mobility and Urban Agenda, which was responsible for signalling and making thedetour effective. This procedure, in addition to entailing considerable time between
communications and coordination of personnel, also increased risk situations, by having
agents on the road in charge of signalling and allowing vehicles to pass in foggy conditions
while the detour was being made effective.

Figure 4 - Manual detour by means of physical lane markings on A-8.

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Figure 5 - Manual detour by means of physical signalling on access to A-8
The characteristics of the fog concentrated in this environment, which is capable of reducing
the visibility distance very quickly, covering the entire stretch of motorway in less than aminute, make it necessary to have an agile system that allows the closure of the motorway
to be applied when necessary.
The automated detour, therefore, is designed to facilitate the existing methodology,
eliminating the need for agents on the road, with the consequent reduction of occupationalrisks and reducing the time required for coordination between the different entity involved.
Furthermore, this automated system aims to reduce the time from the moment the detour or
opening of the road is necessary until it becomes effective, guaranteeing the safety of road
users and improving the management of the road's operation.
The current detour methodology proposes to apply new technologies to send/receive
information on road conditions, infringing vehicles and alternative routes in real time. For
this purpose, various ITS equipment such as Variable Message Signs, beacons,surveillance cameras (CCTV) and illuminated signs are installed in the area.

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Figure 6 – Detail of the diagram of the equipment installed on the affected section of
the A-8 and its operation.
In this new methodology, the detour is established automatically from the North-West Cantabrian Traffic Management Centre and the steps to be followed are summarised below:

Detection: based on the values of the visibility and wind parameters received from thedevices installed on the road (weather stations and CCTV), the level of visibility isevaluated at the Northwest - Cantabrian Traffic Management Centre and it is detected
when the visibility on the stretch is less than 30 metres or the wind speed is higher than
130 km/h and it is therefore necessary to close the road and detour vehicles. This iscontinuously monitored through a computer tool that contains the signalling protocol andinforms in real time of the situation on the stretch.

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Figure 7 - Continuous monitoring system for weather conditions on the A-8.
Northwest - Cantabrian Traffic Management Centre. DGT. Ministry of the Interior.
SpainSignalling panels: Once low visibility or high wind speeds have been detected, thecorresponding speed limits, or the closure of the road and detour to the N-634, aresignalled from the North-West - Cantabrian Traffic Management Centre. The
corresponding warnings to drivers are displayed on the Variable Messaging Signs(VMSs) installed at the beginning and end of the section. In addition, the luminous
beacons installed on the pavement are lit to direct vehicles, as shown in the following
figures.
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Figure 8 – Variable Message Sign and pavement markings. A-8 Motorway. Alto delFiouco (Lugo). SpainControl: In addition, to ensure that vehicles comply with speed restrictions, two speed
cameras have been installed, as well as traffic lights equipped with red light cameras at
the motorway's detour points.

Figure 9. Variable Message Sign and traffic lights with red light cameras. A-8
Motorway. Alto del Fiouco (Lugo). Spain
3.3

ADDITIONAL BEACONS TO THE AUTOMATED DETOUR

As a complementary method to the automated detour, a system of beacons has been
implemented to detect the presence of vehicles in low visibility conditions. Similar to the
cantonisation of railway tracks, the beacons are installed on both sides of the road, 50
metres apart, and their function is to warn drivers of the presence of other vehicles on theroad in low visibility conditions, so that they can adapt their speed and keep their distancefrom other vehicles.
The system of beacons for the detection of vehicles in low visibility conditions has alreadybeen put into operation on the O Fiouco stretch along a length of 4.28 km. The following
images show how it works. In the presence of dense fog, with visibility less than 150 metres(yellow level), the lower amber lights of all the beacons installed on the stretch are activatedto alert vehicles to the situation. Then, as soon as a vehicle enters this zone, the upper red
light of the beacons closest to the vehicle on both sides is switched on to warn the following
vehicle that another vehicle is travelling on the stretch. As the vehicle advances along thestretch, the following beacons are lit, and those 100 metres away from the vehicle areswitched off. In this way, each vehicle has two beacons lit from behind, alerting road users
that, in the next 100 metres, there is another vehicle driving ahead and that they should
adapt their speed and keep their distance.

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Figure 10 - Diagram of the operation of detector beacons in low visibility conditions.
A-8 Motorway. Alto del Fiouco (Lugo). Spain

Figure 11 - Detector beacons in low visibility conditions. A-8 motorway. Alto de O
Fiouco (Lugo). Spain
In order to inform drivers of the meaning of these beacons, so that they proceed with caution
instead of stopping at a red signal, vertical signs explaining the system have been installedat the beginning of the section.

Figure 12 - Vertical sign located at the beginning of the section. Alto de O Fiouco(Lugo). Spain[9]

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ORIGINAL VERSIONNO TECHNICAL CHALENGES

One of the main obstacles or barriers in this case was precisely the definition of an action
protocol for a novel situation for which there were no precedents at national level.
It should be noted that another of the main barriers to overcome was the change in drivers'
behaviour when passing through this area. Although the number of offenders who ignore
and fail to comply with the detour is very low, this stretch already has a special singularity interms of fog and wind, and not all drivers are used to driving in these adverse conditions.
This special feature refers to the fact that the fog completely covers this stretch in less thana minute, so drivers have to react quickly.

5

ASSESSMENT

5.1

EFFICIENCY AND EFFECTIVENESS ANALYSIS

5.1.1

Analysis of the efficiency of automatic vs. manual detour

As indicated above, the weather situation in the area is highly variable from one moment to
the next (fog appears and disappears in a matter of minutes), so this factor, added to thefact that the closure of the dual carriageway was carried out manually using traditionalsignalling and beaconing elements, meant that the dual carriageway remained closed for amuch higher percentage of hours than the visibility recorded below 40 metres, generating a
low efficiency in the use of the road, around 40%.
From the implementation of the automated detour in December 2016 until theimplementation of the new fog protocol on 25 January 2022, a total of 2,313 hours withvisibility below 40 metres have been recorded on this section. This would have meant 5,302
hours of closure of the motorway with the manual detour methodology, while with theautomated detour this figure was reduced to 3,405 hours of effective detour, which meansa total of 1,897 hours of "savings" (equivalent to 79 days) in which the motorway could havebeen open to traffic.
5.1.2

Analysis of the efficiency of the new protocol with presence detecting beaconsWith the implementation of the beacon system on 26 January 2022, 42 hours of visibility ofless than 30 metres have been recorded up to 31 December 2022, which means 78 hours
of detour, compared to the 314 hours recorded with visibility of less than 40 metres thatwould have led to the closure of the motorway for 462 hours according to the previous
protocol. This means 384 hours (equivalent to 16 days) during which the motorway was
open to traffic.
5.1.3 Analysis of Operation and Effectiveness of Detours
From the point of view of the operation and effectiveness of the detour, from December, 152016 to December 31, 2022, it has been detected that 0.8% of the total number of vehicles
circulating on the section continue on the dual carriageway despite the closure, which means
99.20% compliance with the signalling.

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In view of these results, the new detour methodology has had a significant effect on
improving the efficiency of traffic operation and increasing the number of operational hoursof the motorway. This effect is even greater thanks to the use of the new detector beacons,
which have made it possible to reduce the value of the visibility limit to 30 metres, from which
the detour is made.
5.2

ROAD SAFETY

From the point of view of road safety, the automated detour has avoided the physicalpresence of personnel on the motorway for the manual installation and removal of verticalsignage and cones every time it was necessary to close the motorway, so it is a risk thathas been eliminated.
It should also be noted that, since the implementation of the system in December 2016 todate, a total of two accidents have been recorded in foggy conditions: one involving a rearend collision with two minor injuries, and another involving an animal run-over with noinjuries. No accidents with fatalities or serious injuries have been recorded.
5.3

LESSONS LEARNEDThe main lesson learned is the vital importance of effective detection and communication.
Initially, the process of manually closing the road meant more time, cost and risk on theroad. However, the installation of the appropriate equipment has enabled more directcommunication with road users, reducing time and increasing efficiency and safety.
It is therefore essential in road management to have accurate information in real time toenable the right decisions to be made at the right time.
This system has also shown that, on occasions, the combination of various strategies orsolutions already existing on the market is the best way to find the right solution.
5.4

COST

The cost of the installation of the automatic detour elements was part of the ITS equipment
improvements in the area.
The cost of installing the detector beacons was part of the improvements to the maintenanceof the area. The project for the installation of the detector beacons between KP 545+400 to
KP 549+680 had a total cost of 873,127.15 euros.
6

FUTUREThe good performance of the system, and its proven effectiveness, makes it likely to be
used on other roads with similar problems.
In the future, with the advance of vehicle-to-road communication technology, it will bepossible to send information about road restrictions directly to the vehicles circulating in thearea, as a complementary method to the communication to the user by means of the VMSs.

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ORIGINAL VERSIONREFERENCES
1. ORDEN de 27 de diciembre de 1999 por la que se aprueba la Norma 3.1-IC. Trazado, de la Instrucciónde Carreteras.
2. “Estudio de la estabilidad del tráfico en puentes de carretera. Influencia del viento lateral”. Tesis doctoral.
Javier Oliva Quecedo. ETSICCP, UPM. Madrid 2011.
3. Protocol for operating the A282 DartfordThurrock River Crossing during periods of strong winds”.
Highways Agency Protocol.
4. Traffic restrictions due to wind on the Ferhmarnbelt Bridge”. Memorandum. FemerBælt. June 2005.
5. [Website on the operation of various bridges in the USA and Canada.]. http://www.cbbt.com/travelinformation/weather/;http://www.mdta.maryland.gov/Emergency/Emergency_Info.html;
http://www.confederationbridge.com/travel/restrictions.html
6. [Website on the operation of various bridges in the UK].
https://www.severnbridge.co.uk/Home.aspx?.Parent=status3&FileName=high-windssystem6/;http://www.tayroadbridge.co.uk/[12]

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