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You can do this, you should do that, you may do this – but nobody really has to do anything. This aptly sums up the guidelines that specify how road work zones should be designed throughout Europe. First steps have in fact already been taken towards harmonisation. Ten years ago, the European Commission's "ARROWS" (Advanced Research on Road Work Zone Safety Standards in Europe) study was drafted and is still the only basic study to be performed on this topic. The result of the study was a practical handbook with recommendations for uniform European safety standards for road work zones. How this is being implemented in the individual countries can be seen by taking a trip through Europe's road work zones. All the examples below, however, leave room for many exceptions and special provisions which are not listed here.

Lane tapers
ARROWS recommends a maximum ratio of 1:20 for lane tapers. In other words: The length of the taper area must be 20 times as long as the displacement width. If a lane is tapered across three metres, then the taper area must be at least 60 metres longs. This corresponds to Germany's guidelines for lane tapers leading to the opposite lane. Lane tapers to a lane running in the same direction only need to be 10 times as along. This factor of 10 is also applicable in Finland. Although no road work zones have been inspected in Finland, this dark horse should still be included in the comparison of guidelines. The Netherlands, the UK and Switzerland specify lengths for lane tapers: These are generally 300 to 600m in the Netherlands, 200m per closed lane in the UK, and in Switzerland around 80 metres when tapering from one lane to oncoming traffic and 80 to 125m in the case of two lanes. This is completely different in Austria. The road work zone manual issued by Austria's ASFINAG, which privately runs the entire motorway and national road network, makes the minimum length dependent on the speed limit: i.e. at least 130m at 60kph, at least 150m at 80kph. Spain, France and Slovenia have made life much easier for themselves: There are no guidelines for this topic. The latest test clearly showed that lane tapers in these countries do not comply with the ARROWS standard, although this was also true in Switzerland and Germany despite the guidelines in force there.   

Differences were also found in the way in which lane tapers are illuminated. Italy is a shining example where lane tapers have to be lit by road lights or balloon lights. The guidelines in Germany, Spain, France and Finland specify warning lights, as does Switzerland where guiding humps with reflectors are used. Warning lights are only required in Denmark when lane markings are difficult to see. There are no requirements in Austria, Slovenia or Croatia. Exemplary solutions despite the fact that there are no requirements were found in the UK and the Netherlands where road work zones are lit up by road lights. The inspectors also found balloon lights at some road work zones in Austria.

Width of traffic lanes
The right lane (slow lane) should be at least 3m wide, the centre and/or left lane 2.50m. If there is only one lane per direction, these should even be 3.25m wide. At least that's was the ARROWS study recommends. In Austria, Switzerland and Germany, the traffic lane width is generally dependent on traffic routing. The speed limit is also decisive in Austria and Switzerland, whilst the length of the road work zone is additionally considered in Austria and Germany. In Germany and Slovenia, the right lane (slow lane) should be at least 3.0m wide and the left lane at lest 2.50m. Lane width in the Netherlands also depends on the speed limit. If the speed limit is 90kph or more, the minimum required width for the right lane (slow lane) is 3.25m. If this cannot be achieved, speed must be limited to 70kph. The left lane can then be narrower, but is only open to passenger cars. In Italy, a minimum width of 3.0m is generally recommended and this was highly appreciated by the inspectors. In the UK, the type of traffic rather than the location of the lanes was decisive. Lanes for passenger cars and smaller vehicles should be at least 2.50m wide and lanes for HGVs at least 3.0m wide. In Denmark, width depends on road classification. Generally speaking, the right lane (slow lane) should be at least 3.50m wide and the left lane 2.20m wide. However, the inspectors found this to be too narrow in the two Danish road work zones. There are no requirements for minimum width in force in Spain and France.    

Lane markings
According to the ARROWS study, all signs, markings or equipment which do not match the current road work zone situation should be removed, covered or converted. This is taken very seriously in France. All original markings must be completely covered and likewise in Italy for road work zones that are in place for more than seven days. In the UK, the Netherlands and Finland, this only applies when the original markings are dangerous or confusing. Switzerland, Germany and Denmark have made life much easier for themselves; here, yellow lane markings quite simply prevail over white markings which do not have to be removed unless they are particularly confusing, but this only applies in Germany. Here, the assessments made by road work zone designers differed in many cases from those of the test inspectors. Danish road work zone designers solve this problem quite simply by driving through the road work zone at night in order to see for themselves whether both lane markings can be clearly distinguished from each other. If not, then it's time to start scrubbing. There are no requirements in force in Austria, Slovenia and Spain.

There is a surprising consensus in Europe when it comes to material for road markings. Retroreflective material is required everywhere except in the Netherlands where no mention is made to this in the guidelines. This unity is also reflected in the test.

Separation of bi-directional traffic
The ARROWS study recommends the use of mobile protective barriers to separate bi-directional traffic. Germany and Austria have followed this recommendation, especially for longer-term road work zones. In Switzerland, this only applies to 4+0 traffic routing where two lanes meet in each direction. In the Netherlands, the separation of bi-directional traffic depends on the maximum speed permitted: Traffic posts are sufficient at 70kph, whilst mobile protective barriers are used at 90kph. In the UK, on the other hand, a buffer area must be set up, which is separated in the centre using reflective markings and cones. Protective barriers are also often used. Oncoming traffic in Spain is separated by small traffic posts placed on top of guiding humps or double orange markings, depending on the accident risk. In Italy, traffic cones suffice if the road work zone is installed for two days or less. Just like in France, traffic posts are required for longer-term road work zones. Nothing of the kind is needed in Slovenia where lane markings suffice. The test showed that apart from a few exceptions bi-directional traffic was safely separated at all the road work zones inspected.   

Lay-bys and emergency lanes
The ARROWS study recommends lay-bys. However, it does not contain any further details for this. This issue is handled very differently in the different countries, depending on the length of the road work zone. Germany's guidelines foresee lay-bys wherever possible for long-term road work zones that are one kilometre long or more. These lay-bys were far and few between at the road work zones inspected. Lay-bys are required in Denmark for road work zones that are 500 metres or longer. Austria's ASFINAG manual calls for lay-bys every three kilometres for road work zones that are more than 6 kilometres long if there is no emergency lane provided. This is completely different in Switzerland where the average daily traffic volume is used as a parameter. An emergency lane must be generally provided for road work zones with more than 25,000 vehicles per lane per day. If there is no emergency lane, lay-bys must be set up wherever possible. Another variant was found in the Netherlands, albeit it one that is not mandatory: video surveillance in areas where there is no room for lay-bys or an emergency lane. If a vehicle comes to a halt, the lane can be closed immediately. This problem is bypassed completely in the UK by offering a free tow-away service which is on call around the clock and can remove broken-down vehicles quickly from traffic. There are no requirements covering this issue in Spain, France, Slovenia and Italy – and despite this, all the road work zones inspected in France and Italy did have lay-bys.

Points of entry and exit
ARROWS recommends a deceleration lane of at least 70m in the points of exit and of at least 50m in the points of entry. This is also specified in the German guidelines. Sudden points of entry without acceleration lanes, controlled by a stop sign, should only be used in extremely exceptional cases in Germany and speed should be limited to 60kph. The speed limit is also decisive in the Netherlands. A deceleration lane of 150m is required at 70kph and of at least 190m at 90 kph. The acceleration lane should be 65m or 85m long, respectively, otherwise signs must installed to inform motorists of very short lanes. This, however, was not necessary at any of the Dutch road work zones which were the only road work zones in the test to comply with the recommendations of the ARROWS study. In Italy, the deceleration lane must be at least 108m long whilst no minimum length is specified for the acceleration lane. This problem is approached from a completely different perspective in Switzerland: If lanes are too short, the speed limit must be reduced. In Austria and the UK, the length depends on the local conditions whilst no restrictions are in place Spain, France and Slovenia.

The same muddle can be found when it comes to nighttime illumination of points of entry/exit: Warning lights are required in France and Finland, whilst in Denmark, warning lights are only required when lane markings are difficult to see. Austria, Switzerland, Germany and Italy have come up with a very diplomatic solution here: Warning lights can be set up, but this is not mandatory. Points of entry/exit should be illuminated in the UK. As already explained above, in the UK and the Netherlands, most road work zones are illuminated by road lights.

Separation of the work area
ARROWS recommends sufficient buffer zones between flowing traffic and the work area along with longitudinal separation using traffic posts every 20m. In the UK, France and Germany, guiding traffic posts are placed on lane markings. Warning lamps are additionally used in Germany. The work area can also be separated using guiding elements or mobile protective barriers. High protective barriers or guiding traffic posts are used in Spain depending on the accident risk. Protective barriers are required in Switzerland. In Denmark, steel protective barriers are required if the speed limit is higher than 50kph. The inspectors, however, came across weaknesses in the separation of the work area at all the Swiss and Danish road work zones inspected. The same rules as for bi-directional traffic (see above) apply in the Netherlands. In Finland, steel protective barriers must be used if lanes are closed on routes with heavy traffic or if repair work on bridges is to be carried out. Requirements in Italy and Austria are just as rare as in Slovenia where, however, concrete protective barriers should not be used if there is a risk that motorists could collide head-on with these barriers.

Conclusion
The requirements for designing road work zones and the recommendations of the ARROWS study are being implemented in very different ways. The solutions, however, cannot be simply classified as good or bad. Having said this, the task now involves identifying the optimum design for road work zones and providing those in charge with a basis for their work. But this will require comprehensive accident and behaviour studies like those demanded for many years by Europe's motoring clubs. And once again, Europeans will have to pull together.