Companion Project on A4 Brescia Verona Vicenza Padova

Luca Studer / 08 May 2017 15:58

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Description

The Companion project was carried out by the Società Autostrada Brescia Verona Vicenza Padova, manager of the 146-km-long motorway section E66 (A4) between Brescia and Padova.
Serious accidents occurr because of fog and induced the Concessionary Society to implement a system aimed at timely warning motorway users when visibility is very low. The aim is to minimize the risk of accidents and to “drive” users within the foggy area, encouraging them to reduce speed to match the low visibility. This system consists in apposite lighting posts placed on the carriageway side. It also aims at avoiding other risks, such as the formation of queues and traffic slowdowns in particular.

Objectives of the project

The Companion project consists in a system which immediately warns motorway users of an impending danger, thanks to a lighting posts system placed on the left-hand side guardrail of the carriageway.

The system takes into consideration two main dangers:

  • the formation of thick mist or fog with a consequent reduction of visibility;
  • crucial traffic slowdowns and queues formation, also as a consequence of an accident.

These types of danger are detected automatically by apposite visibility and speed sensors installed along the section. Data transmitted by these sensors let the led poles activate automatically and real-time on the sections subject to the actual danger, thus allowing upcoming users to slow down in time.

Light posts can also be used to signal other potentially dangerous situations, such as work in progress, carriageway narrowing, motionless vehicles or other obstacles on the road.

The Companion systems mainly aims at:

  • preparing and installing a wide-scale system able to “warn” motorway drivers in case of an impending danger;
  • using the system also as a means to induce drivers to reduce speed in case of low visibility (fog);
  • reducing as a consequence the number of accidents, in particular those caused by the first one;
  • make traffic more smooth flowing and homogeneous in dangerous situations.

Results/Lessons Learnt

The Companion project was carried out by the Società Autostrada Brescia Verona Vicenza Padova, manager of the 146-km-long motorway section E66 (A4) between Brescia and Padova.

This motorway section is subject to a considerably high traffic level (271,400 vehicles a day on average and 4,575 million vehicles per km in 2003) and to a density of traffic (theoretically 85,784 vehicles a day on average in 2003) which is second in Italy only to the section between Milan and Brescia on the same motorway E66 (A4).

Furthermore, visibility is frequently reduced on this section during winter, both because of widespread fog, which often covers wide areas of the Po River Valley, and because of local fog or fog banks. Fog banks are also caused by the undulating geographical features of the region the motorway runs through, which favour the stagnation of cold and moist air in lower areas and as a consequence the formation of fog.

Even serious accidents occurring because of fog, induced the Concessionary Society to implement a system aimed at timely warning motorway users when visibility is very low. The aim is to minimize the risk of accidents and to “drive” users within the foggy area, encouraging them to reduce speed to match the low visibility. This system consists in apposite lighting posts placed on the carriageway side. It also aims at avoiding other risks, such as the formation of queues and traffic slowdowns in particular.

The project was initially implemented as an experiment on a short section of 9 kilometres (Soave – Montebello). Afterwards it was applied to a further section of 19 kilometres (Sirmione – Sommacampagna) and is being extended on a section of 19 kilometres (Grisignano – Padova Est).

Objectives

The Companion project consists in a system which immediately warns motorway users of an impending danger, thanks to a lighting posts system placed on the left-hand side guardrail of the carriageway.

The system takes into consideration two main dangers:

  • the formation of thick mist or fog with a consequent reduction of visibility;
  • crucial traffic slowdowns and queues formation, also as a consequence of an accident.

These types of danger are detected automatically by apposite visibility and speed sensors installed along the section. Data transmitted by these sensors let the led poles activate automatically and real-time on the sections subject to the actual danger, thus allowing upcoming users to slow down in time.

Light posts can also be used to signal other potentially dangerous situations, such as work in progress, carriageway narrowing, motionless vehicles or other obstacles on the road.

The Companion systems mainly aims at:

  • preparing and installing a wide-scale system able to “warn” motorway drivers in case of an impending danger;
  • using the system also as a means to induce drivers to reduce speed in case of low visibility (fog);
  • reducing as a consequence the number of accidents, in particular those caused by the first one;
  • make traffic more smooth flowing and homogeneous in dangerous situations.

Success story description

Safety

Safety will potentially increase thanks to:

  • The technical effectiveness of the system. It can give a timely and consistent warning in case of an impeding danger;
  • The reduction, although limited, of vehicles speed when light posts are activated;
  • The lower number of accidents and collisions recorded on the historic Soave Montebello section.

Effectiveness

The system proved technically effective and can automatically activate when visibility is low (nearly 1.800 activations per year in the last years of operation on the Soave – Montebello section and over 6.000 activations caused by queue in the first eight months of operation on the Sirmione – Sommacampagna section).

The system activates in a consistent and timely way facing the danger to be signalled and can:

  • Follow and go ahead queues expanding before or ahead. It always activates well ahead the point of sharp braking;
  • Follow the extent of a foggy area, thus effectively warning users approaching a fog bank;
  • Provide consistent information thus avoiding the excessive alternating of activation and deactivation phases and properly filtering temporary and hardly relevant changes of parameters controlled by sensors, without having to change the state of activation in vain.

In analysed cases regarding light posts activations due to low visibility, a speed reduction of vehicles from -0,4 to -15,2 km/h was recorded, corresponding to a percentage of -0,4% and -13,6%.

Safety distance between subsequent vehicles showed no clear changes, but alternating increase and decrease.

In Table the indicators of the Companion system are summarised. 

Table – Indicators summary of the Companion system.

Objective

Sub- Objective

Indicator

Statistical basis

Result expected before the implementation (qualitative)

Result surveyed after the implementation (qualitative)

Result surveyed after the implementation (quantitative)

Status of achievement of the aim

Safety

accidents frequency

(change)

number of accidents per km

(comparison between the Soave-Montebello section and the average on the motorway

BS-PD)

from January 2001 to June 2004

lower than the average on the motorway

BS-PD

lower than the average on the motorway

BS-PD

-10,6%

with respect to the average on the motorway

BS-PD

very good

analysis of the number of black dots

 (comparison between the Soave-Montebello section and the average on the motorway

BS-PD)

from January 2001 to June 2004

lower than the average on the motorway

BS-PD

lower than the average on the motorway

BS-PD

---

fairly good

accidents frequency when visibility is low

number of accidents per km

(comparison between the Soave-Montebello section and the average on the motorway

BS-PD)

from January 2001 to June 2004

lower than the average on the motorway

BS-PD

slightly higher than the average on the motorway

BS-PD

+4,8%

with respect to the average on the motorway

BS-PD

poor

number of vehicles involved per accident

(comparison between the Soave-Montebello section and the average on the motorway

BS-PD)

from January 2001 to June 2004

lower than the average on the motorway

BS-PD

lower than the average on the motorway

BS-PD

-28%

with respect to the average on the motorway

BS-PD

very good

Efficiency / impact on users

time and space coherence of danger warnings

comparison between surveys of sensors (real danger)

and activation status of light posts

analysis of several episodes of visibility reduction / sudden slow-downs

danger situations signalled in a coherent and timely way

danger situations properly signalled in sufficient space and time advance

---

very good

speed adapting after a danger warning

speed of vehicles in transit (km/h)

analysis of several episodes of visibility reduction; speed comparison with/without activation of light posts

speed reduction when light posts are activated

speed reduction when light posts are activated

lowest decrease surveyed:

-0,4 km/h (-0,4%)

highest decrease surveyed:

-15,2 km/h (-13,6%)

sufficient

safety distance adapting after a danger warning

time distancing (headway) classified by classes and measured in seconds

analysis of 3 episodes of visibility reduction: headway comparison with/without activation of light posts

slight increase in headway when light posts are activated

slight increase in headway in only one of the episodes under examination

episode with the most remarkable change

-6% of vehicles with low headway

(< 1,5 secs)

+5% of vehicles with high headway

(> 4,5 secs)

poor

Environment

N/A

---

---

no impact expected

     

Accessibility

N/A

---

---

no impact expected

---

---

---

Integration

N/A

---

---

no impact expected

---

---

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Status
Completed
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Safety Traffic data traffic management
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