SPIs on Daytime Running Light

Introduction

Daytime Running Lights (DRL) SPIs are usually considered in the form of the percentage of vehicles using daytime running lights. The general indicator can be estimated for the whole sample of vehicles, which were observed in the country. Similar values can be calculated for different road categories and for different vehicle types. The road categories to be considered are: motorways, rural roads, urban roads, and DRL-roads ( where the term “DRL roads” implies the road categories where the usage of DRL is obligatory). The vehicle types to be considered are: cars, heavy good vehicles (including vans), motorcycles and mopeds. In countries where automatic DRL was introduced long time ago (e.g. Sweden, Norway) the DRL usage rate is close to 100%, thus the DRL usage rate as a behavioural safety performance indicator does not have practical implications any more. In general, once the option of automatic DRL is introduced Europe-wide, the DRL indicators will lose their importance.

Read more about SPIs for DRL in the report Safety Performance Indicators: Theory

Measurement methods

The SPI Manual provides further technical information on calculating DRL use rates for different road categories, for different vehicle types, for specific legal category of DRL roads, and for the whole road network. Practical measurement guidelines are he following:

• SPIs on Daytime Running Lights should be observed for 4 different vehicle types: 1 cars, 2 heavy good vehicles, 3 motorcycles and 4 mopeds.
• The sample should be stratified according to three road categories: A – motorways, B – rural roads, C – urban roads.
• For each stratum (road category), at least 10 (recommended - 30) observation sites should be selected at random, accounting for the total amount of roads in the national road network. Each site is a road section of certain category of roads. The number of observations per site should be at least 100.
• As a rule of thumb, for each road category and for each vehicle type a sub-sample should be over 400 vehicles.
• For each vehicle observed and included in the sample, the following data should be collected:

• Day and hour of observation
• Road category
• No of site (according to road number and road section)
• Lane of travel
• Direction of travel
• Vehicle type
• Using DRL: yes/ no

Foreign vehicles should be excluded from consideration.

Recommendations

In total, 9 DRL SPIs are recommended for application, which are: the total usage rate and the percentages of vehicles using DRL according to four road types and according

to four vehicle categories. To estimate the above SPIs, each country should perform an annual survey of the DRL use.