Reflective Pavement for road safety and energy saving a must Since 18 January 2017, in the Netherlands, the knowledge module Wegdekreflectie - Optical properties of road signs is in use. The Knowledge Module can be found online at the CROW* under the modules asphalt pavements and concrete pavements.

By Piet Zijlstra

I myself have been busy with reflective pavements for more than twelve years, and I was a member of the working group that developed the Knowledge Module. I do not like baked air at all, so I worked with colleagues, suppliers and various clients of municipalities and provinces to investigate the possibilities of reflective pavements in public space. Because it is being used more and more by clients in innovation, I also see that the clock is heard, but it is often not known where the valve is hanging. The disadvantage of a knowledge module is that some people suddenly think they have enough knowledge. That is not true of course. What we have been working for years and researching, you do not even get in a digital publication. This is intended to give handlers to contractors and contractors and suppliers, but the correct application and good effects come from advice. No situation is the same. For advice, we are always available as members of the CROW working group.

Handful An example of how it should not be came to me from a large municipality last month. It only asks for reflective asphalt in the tender, and only describes the properties of the reflective rock in the total asphalt mixture. With a lowest price quote (this happens unfortunately too much) a contractor with literally a handful (30 grams) of the reflective stone layer in a ton (1000 kg) asphalt would already meet the requirements. Result: a big disappointment! And worse: if public lighting is considered, this gives a bad lighting on the road. In addition, such a client will not apply reflective pavement again: a missed opportunity.

It's quite different if you use the right combination of reflective stone, production and processing. This applies to asphalt, surface treatments and reflective paving stones. We have this knowledge in our company. For more than twelve years. PolyCiviel specializes in the application of road surface reflection in the broadest sense.

In the forefront in Europe On January 26, the new Dutch public lighting directive NPR13201: 2017 was commissioned as a successor to the well-known Dutch ROVL 2011. This included reflective pavements, for the first time. The Netherlands is in the forefront of Europe. Important to this is the vertical illumination intensity, in subject jargon the Ev. This includes face detection, but also for seeing road users like pedestrians and cyclists as well as seeing obstacles. For lighting experts, it was already a question of whether you can get the task with current LED lighting. The question is whether the Ev has to be 1.0 lux to have sight and obstacle recognition at 4 m distance. That's not necessary. With reflective pavements, Ev can improve up to 0.5 lux, so light pollution does not need to occur either.

Observation For road users, it is important to perceive facial features with other road users. For social security, it is important to determine the direction of view, emotional state, intention (body language) and identity, preferably at 4m distance. Based on this, one can assess whether the other may pose a risk and respond to it in a timely manner. For road safety, it helps to see the viewpoint in a possible conflict situation. This is important information for cyclists, for example, whether they have been seen by a motorist. This is also due to the increasing use of led lighting in the public space. Led often gives a different image than conventional lighting. By providing good vertical illumination, vertical obstacles and persons are visible in the viewing area. In the Netherlands, therefore, more attention has been paid to the application of road decks with higher road reflections, to achieve the same result with less light. In addition to the primary purpose of perceiving and viewing the environment, we also consider increasing traffic and social security, comfort and living ability as the result.

Luminance In the design of public lighting for roads with a traffic function, the luminance concept is counted. The advantages of increased road surface reflection can therefore be included relatively easily in the design. In areas of residence, reflective pavements, as mentioned earlier, also affects the quality criteria for public lighting. This influence was not yet included in the light design or light calculations of residential areas. Using the measurement value Rho, it is possible to calculate the influence of the reflection on the vertical illumination intensity. Optically, Rho is a reflection rate, also known as Albedo. Rho is conveniently compared to an easily measured Y value.

Photo PolyCiviel Piet Zijlstra - Measuring (Rho) Y-value (whiteness) Asphalt research reflection with MiniScan EZ.

The Y value indicates the amount of light reflected by a percentage, in percent. In calculation software (such as Dialux), the Rho value can be used to calculate the indirect vertical illuminance. Carrying out the road surface reflection in residential areas has a significant impact on the qualitative requirements.

As a (bad) example, a pilot with led lighting at a municipality in the north of the Netherlands.

Photo: PolyCiviel Piet Zijlstra. Luminance measurements at Led pilot.

We have done luminance measurements (Rl, Qd and Ev) and looked at the image of light, because that is the case: In an effort to further alleviate the lighting in this public space, this road has become a no-go area. A combination of mesopic illumination and poor light design leads to a night vision where even walking the dog in the dark becomes adventurous. The energy-saving potential in this case is based on reduced burning hours with smart control, and new lighting dimensioning.

Results light measurement and conclusions The following values are measured at 19:30 h P.M. :

- Eh, : about 3 lux. Equality: approx. 0.2 (grid measurement) = P5

- L, : approx. 0.2 cd · m-2

Starting from the ROVL-2011 where the OVL in this Avenue was designed, the required lighting quality should be M5 during the highest traffic intensities until about 21.30 h in the evening. (Relatively high traffic).

This corresponds to Eh approx 7 lux. There can be dimmed hereafter to minimum P5 (Eh, 3 lux night level). From about 6.00 h in the morning about 100% illumination level for the dark days.

Conclusions

1. Asphalt is objective as measured relatively dark (Y-CIE 3 to 4%) causing the lane Low ambient brightness (adaptation) 2. There is little lane exposure of the headlight headlamp (low Rl value about 3 to 5 Mcd · m-2 · 1x-1) 3. The current 100% level at 19.30 h. P.M. should be about the night level with relatively few Traffic 4. Why is there no horizontal road marking as visual guidance? Now you can become uncertain by getting glare from oncoming traffic and low light level. 5. With reflective pavement the situation can be much better as Ev can improve with up to 0.5 lux.

What is also noticeable is that light calculations are basically based on the visibility of a 23-year-old while living in an aging society. Last month there was an item dedicated by the NOS* to the aging driver. More -over-65s- people are driving in a car. This is evidenced by figures from the Central Bureau of Statistics (CBS*). In 2005 there were still 408 cars per thousand over-65s. By 2015 there were 521 cars, and those cars are being driven more. In 2005, nearly 8.5 billion km were taken by the elderly, in 2015 this increased to 14.2 billion km. That is an increase of about 68%. At the same time, the elderly are more often involved in road accidents. The proportion of elderly people in traffic deaths has increased, and this increase is not just due to the aging population. Figures from the CBS of 2015 show that there were 119 80-plus people after a traffic accident. In 2010, this was still 94 80-plus. Figures about 2016 have recently become available, and those figures are still worse than expected. The increase was highest in the age range 18 to 25 years and people over 75 years old. Smartphone usage is a cause of traffic accidents, but the road construction is of course very important.

Dutch Minister Schultz called on people to appeal to older drivers on their driving behavior: "If your father or mother or someone else in your area is in danger of driving, then it is very good to say that." Again, this group of road users with a much higher light-need make more use of the road. The light image in the previous image is considerably improved by applying a reflective road surface. Below is the example in the Groningen municipality of Haren, where 40% Granusil has been used as a reflective stone in the road surface. A pleasant improvement for "seeing and be seen".

Photo: PolyCiviel Civil Engineering - Vondellaan Municipality of Haren with + 32% energy saving

In addition to road safety, municipalities, water boards, provinces and Rijkswaterstaat can also save on energy because less power is needed. I'll be the last one who says the light can be switched off. Where necessary, apply light and if possible, outside the urbanized area of the city, without light and with reflective pavements do your thing. In addition, the reflection can cause a lower temperature of asphalt during high summers (8-15 degrees cooler), resulting in less trace formation in certain asphalt mixtures. This will reduce maintenance costs. For example, in the province of Groningen, the municipality of Assen and the municipality of Groningen have used a combination of sound-reducing and reflective asphalt with excellent results.

Photo: PolyCiviel Piet Zijlstra - Contractor Oosterhof-Holman Infra. Apply noise-reducing / reflective asphalt n the Municipality of Groningen

Road Safety In my view, the relationship with road safety literally also has much more value. Traffic accidents cost the society (our big wallet) about 14 billion euros a year in the Netherlands! Traffic accidents have many causes. One of them is smartphone usage. But say that you could now limit 10% of road accidents (think of the elderly and the visually impaired) by reflective pavement and better visibility, which would save us all 1.4 billion euros. Spend this on "more view with less power costs."

Piet Zijlstra,

Owner PolyCiviel Civil Engineering

Kalkoven 3

9351 NP Leek (The Netherlands)

+31 646715859

piet@polyciviel.nl

• CROW is the technology platform for transport, infrastructure and public space. It is a not-for-profit organization in which the government and businesses work together in pursuit of their common interests through the design, construction and management of roads and other traffic and transport facilities. Active in research and in issuing regulations, CROW focuses on distributing knowledge products to all target groups.

• The mission of CBS is to publish reliable and coherent statistical information which responds to the needs of Dutch society. The responsibility of CBS is twofold: firstly, to compile (official) national statistics and secondly to compile European (community) statistics.