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06.05.2025

Preventing Deer and Moose Accidents Through Road Management

Measures - Experiences and Solutions from Finland

Author: KLANG Jaakko Centre for Economic Development, Transport, and the Environment, Traffic System Department, Finland

More than 13,953 traffic accidents involving deer and moose are estimated to occur each year in Finland. These accidents cause at least €92 million in costs and lead to 122 personal injuries (3 fatalities) annually. Deer-related accidents are increasing as both deer populations and vehicular travel increase.

More than 13,953 traffic accidents involving deer and moose are estimated to occur each year in Finland. These accidents cause at least €92 million in costs and lead to 122 personal injuries (3 fatalities) annually. Deer-related accidents are increasing as both deer populations
and vehicular travel increase.

In this presentation, I will describe the methods and measures that have been used and tested in Finland and the situations in which each may be useful. The aim is to improve road safety by reducing the number of accidents with moose and deer. The Safe System approach has been used in the design and implementation of the measures. Human factors have been considered in encouraging drivers to heed warnings and reduce speed on stretches of road where the risk of accidents with a deer or moose is significant, considering the time and place.

DEER POPULATION AND ACCIDENTS
The deer species living in Finland are moose, reindeer, roe deer, wild roe deer, white-tailed deer, and spotted deer. In this presentation, I will focus on moose and deer and the general term I will use for moose and deer will cover moose, white-tailed deer, and wild roe deer.

The moose is Finland’s largest animal, weighing up to 800 kg and growing to a height of over two meters. Moose live throughout Finland and thrive in lush forest landscapes. Moose change their grazing areas during the summer and winter seasons, which also increases the risk of moose accidents in traffic.

 The white-tailed deer is an invasive alien species in Finland, which has spread especially to south-western and southern Finland. The species grows smaller than a moose, reaching a maximum height of 90-110 cm and weighing up to 130 kg. The species thrives in woodland environments close to farmland. The roe deer is a deer of about 65-80 cm in height and weighing up to 35 kg and is found in southern and western Finland. It is found especially in shrubby woodlands, meadows, and field clearings. 

Picture: View of the active deer warning system on regional road 189 from Luonnonmaa in Naantali. The warning area is 1,1 km long

The high number of accidents is due to the natural movement of animals in spring. In addition to the fact that white-tailed deer, wild roe deer, and moose move around a lot in search of food, wild roe deer are driven onto roads because of territorial battles. Other reasons for animals to move at certain times in the spring include calves remaining on their own in the spring, which can cause them to stray onto the roads.

Despite the high number of accidents, they rarely resulted in injuries. In recent years, there have been between one to three road fatalities per year and between 150 and
200 injuries per year in moose and deer collisions. In recent years, about 70% of all moose and deer accidents resulting in personal injury have been moose collisions.

MEASURES AFFECTING DRIVER BEHAVIOUR
Measures to influence driver behaviour include increasing driver awareness of deer, improving deer visibility and limiting driving speeds to give drivers more time to react and avoid collisions. These measures have
been designed and implemented using the Safe System approach. Human factors have been 

considered by encouraging drivers to heed warnings and reduce speed on road sections where there is a significant risk of a collision with a deer or moose.

Raising driver awareness

Communication has proven effects on driver behaviour when it contains new information of interest, aims to influence the driver directly and is reinforced by some measure such as enhanced police enforcement. Information should be regional, road-specific, and time- targeted. It should also be continuous, given that a new generation of drivers enters the road every year.

Warning traffic signs

Warning traffic signs warn drivers of certain stretches of road where moose and deer regularly move, and deer accidents have occurred. Passive traffic signs always have a fixed message, although they may use spotlights or other effects. No studies have been carried out in Finland on the impact of moose and deer warning signs under the Road Traffic Act on driver behaviour. As passive warning signs are often used on road sections where deer are only occasionally present, drivers are unlikely to change their driving behaviour or pay attention to the signs.

Active traffic signs are traffic signs that are activated and warn the motorist only when deer or moose are detected in the vicinity of the roadway. Detection methods have included infrared light, radar, laser, radio frequency beams along the roadway and thermal imaging. All detection methods have the potential for error i.e., false alarms, which, if repeated, often reduce the credibility of the warning system in the eyes of motorists. No comprehensive studies have been carried out in Finland on these methods and their effects on driving speeds and accidents.

Deer detectability

The earlier a driver detects a moose or deer on the road, the better his chances of avoiding a collision. 

Road lighting is commonly used to improve driver visibility in urban areas, at motorway junctions and other potentially accident-prone road locations. Since most deer accidents occur at night, roadway lighting is an important factor in the driver’s ability to see moose and deer. Our studies show that lighting does not affect deer behaviour and tends to increase driving speeds.

Clearing the roadside will give better visibility of the roadside protection area into the forest and allow motorists to spot deer entering the road earlier. It also reduces the amount of vegetation and brush that can attract deer to feed near the road.

Infrared technology systems are available as an option on many new car models. There is not yet enough reliable research data on their effect in reducing deer accidents. A significant proportion of moose and deer collisions in the dark could be avoided if cars were equipped with automatic braking systems with modern night vision technology.

Speed limits

Of all deer accidents, 60% were on stretches of road where the speed limit was 80 km/h. This is explained by the prevalence of this speed limit on the rural road network (general speed limit) and the 80 km/h winter speed limit on main roads. However, the statistics do not show whether the speed limit was obeyed in the event of an accident.

Reducing the driving speed from 100 km/h to 80 km/h gives the driver more time to react and reduces the consequences of a potential accident. In the worst deer accident areas, the change in winter and dark season speed limits should already be implemented in early September, so the lower speed limit is in force during the busiest deer movement period in September-October.

MEASURES AFFECTING THE BEHAVIOUR OF MOOSE AND DEER
Moose and deer behaviour can be influenced by preventing animals from entering the road using different fencing solutions or by making the road crossing unpleasant or frightening using different types of repellents near the road.

Fences are a widely used measure in Finland to limit the access of moose and deer to road areas. At best, fencing can reduce deer accidents by up to 80-90%. However, there are several challenges associated with fencing. Fences should be built 2.2-
2.4 m high and in continuous sections of sufficient length (over 5 km) to avoid simply diverting animals to the ends of the fence.

Fences

Moose and deer are adept at finding fence ends, junctions of crossing roads and other gaps where they can slip into the road area. If no return route can be found, the animal may be trapped between fences for a long time. A deer running in panic on a motorway is obviously a major road safety hazard. Several deer escape routes have been built in Finland, but there is no research data on their long-term effectiveness. Usually, the police are unable to guide a deer caught between the fences back into the forest through the escape road or gate and must put down the panicking deer.

Under- and overpasses

Fences do not eliminate animals’ needs to move around, so fencing should ensure that animals are allowed safe access to the other side of the road. The solution lies in a variety of overpasses and underpasses. Perhaps the best known of these are the green bridges over roads, of which there are fifteen in Finland. Landscaped bridges are particularly popular with deer.

Moose and deer flat crossing

A cheaper but riskier alternative to under- or overpasses is to build a flat crossing for the animals. A flat deer crossing should be built on a stretch of road with a low-speed limit and good visibility, for example in fields or meadows. In this case, the animals are guided and attracted to the desired crossing point by various means. Drivers should be warned as clearly and visibly as possible by warning traffic signs of the deer crossing point.

Access solutions for side roads on a fenced road section

No gate is used at junctions with roads or major private roads, but the fence is placed outside the visibility zone and extends 20 m to the side road. For agricultural and forestry access, a gate is generally used. The distance between the gate and the access road must be sufficient to allow the space between the gate and the road for the vehicle to pass and the gate to open. Alternatively, the gate can be replaced by a deer guard. A deer guard allows vehicles to pass through the junction, but the grid-like deck structure prevents deer (and other hoofed animals) from passing through the junction.

CONCLUSIONS
About 60% of the annual variation in moose and deer accidents in Finland can be explained by the size of the moose and deer population and traffic volume alone. Limiting traffic volumes to reduce accidents is not realistic, so managing moose, white-tailed deer and wild roe deer populations is key to preventing moose and deer accidents.

The Ministry of Agriculture and Forestry has set a target for the number of moose as a natural resource, ranging from 2 to 4 animals per 1000 ha, except in the northernmost part of the country. In Finland, the moose hunting season starts in October and ends in January. The hunting season for white-tailed deer starts in September and ends in February.
 
FEATURES
Many international studies have come to similar conclusions about the effectiveness of moose and deer accident prevention measures as we have in Finland. There is no quick and inexpensive method to reduce moose and deer accidents. Reducing deer accidents is part of transport systems work, wildlife management and ecological planning, which aims to balance the needs of humans and deer. Accident statistics and data collection should be improved to provide accurate and comprehensive information for  planning,  implementing, and monitoring the impact of accident reduction measures and to avoid solutions in land use and transport systems that increase deer accidents.#