PRE2017 1 Groep2

Group members

• Simon Kok (0850085)
• Xueyuan Chen (0961799)
• Lennart Heijnen (0957658)
• Lisanne Grevinga (0946763)

Project definition

The current street lights are based on a system that is extremely outdated. It is possible to reduce energy consumption by large quantities by changing the entire system. This will not only be good for the environment, but it will also reduce costs over time. By creating a SMART light plan, this all is possible while increasing safety and decreasing light polution. As numerous studies have shown, different lighting conditions influence people greatly. By interpreting the results of those studies, a design will be made. The hypothetical design will be made for the residential area Meerhoven.

Objective

The different stakeholders have different objectives. It is the goal of this project to make a design that satisfies all stakeholders.

• Users: This are the people driving, walking, cycling, etc past the streetlights. Their first priority is safety and visibility.
• Society: The society can be diveded in two groups. First there is the people living in the area. Second is the municipality. For these stakeholders, it is important that it is cheap (in the long term). Other wishes could be the mood set by the lighting.
• Entrepreneurs: This are the people designing and making the SMART streetlights. For the companies, the most important is that they can make profit from the SMART streetlights.

Approach

The approach for this project is to start with literature study, to understand the influence of street lights on the objectives of the stakeholders. This research should also contain the monitoring of crowds. Other than the literature study, stakeholders can be further investigated by speaking with the municipality and with researchers of the TU/e lighting group. With the results of these studies, the design requirements can be made. With these requirements and more study into the technical aspects, a design can be made. Finally a prototype will be build in the form of software.

Research

The first research done is in the form of literature study.

Articles

• Research at the TU/e has shown that pedestrians feel safer when their direct surrounding is lit, in comparison when the areas further away are lit. This is applicible to both females and males. Furthermore, it is the result of both stationary and walking pedestrians.

• Visibility is mostly influenced by contrast. This mostly is problematic when there is oncoming traffic. To have a similar visibility, road lighting should be brighter when there is oncoming traffic.

• Switching off lights in areas in England and Wales did not result in increased crime rates. Even though this study took place in other countries, it does suggest that decreasing light levels in the Netherlands will not increase crime rates either.

• Monitoring people is a sensitive subject. Generally people dislike being monitored, even when the data cannot trace back to the individuals being monitored. Even though this example is using monitoring for commercial ends, it might still be important even when safety is the goal.

Case Studies

• In the city of Los Angeles, 140,000 conventional street lights have been replaced by LED lights. Over the span of a year, these lights consumed 63% less energy. This in addition to higher reliability, reduced operating costs by 40%. In addition, crime rates in the area went down by 10%, though the study doesn't mention how they tested the correlation. It also shows that the lifespan of LED street lights are much higher than that of conventional bulbs, but again, no sources are mentioned.

• Analysis show that over a span of 20 years, approximatly €780 per light can be saved by using a networked LED system. Initial investment costs are high, however, payback time is only 6 years.

Projects in and around Eindhoven

There are different smart streetlighting project in the Netherlands.For example, there is a project at Stratumseind in Eindhoven and one at the Goorloopweg in Helmond. These streets are very different from each other. Stratumseind is a big street in Eindhoven with a lot of bars in it. During the night there are a lot of people and most of these people have had some alcoholic drinks, causing a higher risk of aggression on the street. The project at Stratumseind uses lights to make people less aggressive, by using different colours, brightness and light patterns. . Then the Goorloopweg is a street in a sports park. During the nights it is quiet, mostly deserted and dark, although there are occasional pedestrians, jogging or walking their dog, for example. The streetlights on the Goorloopweg they try to create a safe place for people during the night using sensors. When someone walks by a streetlight, it will shine brighter than when no one is around.

Contacting the TU/e Intelligent Lighting Institute

An email has been sent to Antal Haans of the Intelligent Lighting Institute (ILI). Mr Haans is an expert on lighting and social safety and one of the co-authors of the article Light distribution in dynamic street lighting: Two experimental studies on its effects on perceived safety, prospect, concealment, and escape, which is mentioned above. Additionally, he has worked on experiments with smart lighting systems at Stratumseind and in the Markthal at the TU/e. We aim to interview mr Haans on his work on the subject and his findings, so that we can get a better understanding of the needs of the users for a smart streetlight system.

Interview with Antal Haans

Haans worked on a smart street lighting project in a street in the Achtse Barrier in Eindhoven with the goal of saving energy without reducing the sense of safety. As a psychologist he and his team had to think of how such a street lighting system should work. 50 year old lights were replaced by LEDs and infrared sensors were installed. In order to come up with a lighting procedure, he did a research on the TU/e which showed that people prefer having their immediate surroundings illuminated as opposed to places further ahead in the street. Lithuanian professor Zukauskas did similar research and even suggests light in the distance is not needed at all. When a sensor detects a person, the light corresponding to that sensor switches on (from 10%, the base level, to 100%), as well as two lights to the left and right to that light. The lights go from 10% to 100% instantaneously.. The lights then remain at 100% for a minute, mostly for practical purposes while conducting the experiment. After that time, the light would go back to 10% very slowly.

Results: users

Most people participating in this trial felt that the dynamic lighting had added value. First of all, they liked the idea of participating in saving energy. Secondly, they thought the lights switching on for them was welcoming.

There also were some unexpected results: a small number of people living in the streets started looking outside when they noticed lights switching on to see who was there, and they reported that there were a lot of false positives: lights switching on when there was nobody there. This was mostly because two lights next to the light sensing motion would also turn on. A few of the residents became a bit paranoid/anxious because of this. The main problem here is that the residents didn’t have a good mental model of the system: they didn’t know well enough how it worked. When implementing such a system, it should be made sure that the users develop a better mental model. Also, some people were bothered by the suddenness of the lights switching on.

A lot of people actually thought that the basic level of illumination (when no motion is detected) was enough. This could in part be explained because the previous, old lighting was very poor in terms uniformity and horizontal and vertical illuminance and the LEDs were a big upgrade from this. But it does suggest the dynamic system might not be very necessary. On the other hand, the people saying this of course didn’t walk through the street with just the low light level.

During the trial, Haans and his team came to realize cars don't need street lighting in this kind of neighbourhood, meaning the lights could switch on gradually instead of instantaneously (the latter having been chosen with cars in mind).

Results: Energy saving

It was found that while a lot of energy was saved by switching to LEDs, very little additional energy was saved by implementing the dynamic lighting system: about 6€ worth of energy per light per year, which doesn’t make it economically viable, taken into account the costs of installing the wireless communication. Therefore, the system should be simplified. One option is to not use communication: a light simply goes on when it senses a person, without other lights reacting. In Tilburg there is an experiment on this.

Haans did explain that reducing light pollution nowadays has replaced energy saving as the driving force behind the development of dynamic street lighting. He did advise us to go speak with Richard Verhoeven, the researcher who handled the results of this trial in terms of saving energy. Verhoeven has been contacted.

What's left to explore?

According to Haans, one main issue that's important for creating dynamic street lighting is determing the area that should be illuminated for a pedestrian. The complexity of the system depends on this: the amount of lights that should switch on, and thus the amount of communication.

Additionally, while there is some research available about pedestrians, very little is known about interactions with others, especially other street users.

Interview with Richard Verhoeven

Verhoeven also worked on the dynamic lighting project in the Achtse Barrier. Two difficult aspects of the project were that Philips provided the hardware, so the team couldn’t directly make changes to it; and they had to comply with the government regulations for street lighting levels.

Dynamic lighting has to be cost-effective. However, the energy saving in the project only amounted to up to 5 euros per pole per year, so the number of ways to make this cost-effective is limited. The main issue is that the sensors themselves are expensive, so omitting the network wouldn’t cut the costs that much by itself. Infrared seems to be the cheapest, and reliable, but is still expensive; the one used in the project cost 150 euros, so this could never be cost-effective. The total cost of the sensors needs to go down.

Data from the internet about the weather conditions were collected. The effects of weather conditions on the wireless communication system were tested, but the results of this are not available, since there is no funding anymore. The infrared motion sensor that was used can be tuned for different regions. The output is binary, simply whether something is detected or not. When the sensor detects movement for a certain period of time, for example 100 ms, it sends a signal to all light poles in the vicinity, including the light pole that it’s attached to. If there’s still movement after 10 seconds, the signal is repeated. A few pc’s in the area collected all the data. The range of the sensor can be between 2 and 16 meters. One issue with the sensors is that when walking towards it, it doesn’t detect as much movement, so the range is limited.

Without a network, sensor ranges should be sufficiently large. In addition, problems could arise since sensors can’t detect what’s around a corner. There have been ideas about lights being activated not by a motion sensor, but by smartphones. But obviously, any such idea would exclude people. Another idea is to only install sensors at entry and exit points in the street and let the whole area light up when something is detected there. But this would be problematic, because people could leave their house in the middle of the street and nothing would be detected. Also, if people stop or walk slower than expected, the light will turn off at some point.

Current regulations provide minimum light levels (about 5 lux for busy roads, 2-3 lux for residential streets) and also consider the distribution of the light (no dark spots), but if it can be guaranteed that there is no activity at a certain place, it’s allowed to go below this. But there should always be some minimum light. The energy saving compared to non-dynamic LED was about 35%. Since LED doesn’t use a lot of energy anyway, this saving is very small in absolute numbers. One way to make the system more cost effective would be to integrate other sensors into the system, for example to measure pollutions and other environmental factors that might be interesting. This way the network is multi-purpose and more interesting to invest in. Also, a more promising way of dynamic lighting might be to use sensors to make an activity profile of a neighbourhood, and base the light levels at different times in the night on this.

Verhoeven suggests that we should take errors into account to test how well our system behaves. For example, what if a signal from a sensor is somehow lost? What if one of the lights breaks down?

Scenarios

In the project, a street in the suburb of Meerhoven has been chosen. Fistly, because it is a big street where cars come from both directions. Secondly, there is not a lot of work traffic, but only traffic from the people that live in Meerhoven. In this chapter first a description of the street will be given, then the preferences of the user are given and then an example for different scenarios will be given.

Street Description

For the project, it is good to know what the street looks like. The street is a two-way street, that means that traffic can come from both ways. On the street are two different intersections. The first intersection is a 'normal' intersection where all the traffic (pedestrians, cyclists, cars) can go right, left or straight ahead. The second intersection is an intersection where only the cyclist and pedestrians can go all three directions and cars have to go straight ahead. Then on both sides of the streets are parking spaces and streetlights and cars are allowed to drive 30 [km/h]. Those streetlights are standing fifteen meters apart from each other and when nobody is on the street they are on for 40 percent. And at last at the end of the street, the traffic has to right or left. In FIGURE 1 a sketch of the street is given.

Preference users

In this situation there are three kinds of users:

• The pedestrian
• The cyclist
• Driver of a car

For now, the preference of the pedestrian and the cyclist are the same. A cyclist is seen as a pedestrian that walks really fast.

Pedestrian and cyclist

The preference of the pedestrian and cyclist are different in different situations. There are 3 different situations:

• The pedestrian/cyclist is the only person on the street.
• The pedestrian/cyclist is going to the left and a car is going to the right. That means that they are heading towards each other and have to cross each other on the street
• The pedestrian/cyclist is crossing the street

Starting with the first situation, where the pedestrian/cyclist is alone on the street, Haans and de Kort did some research about the preference of a pedestrian walking on the street . The conclusion from this research was that people feel safer when they are surrounded by light rather than that having light in front of them further down the street. So for this situation, the streetlights around the pedestrian/cyclist should be turned on and most importantly the one that is the closest to the pedestrian/cyclist should shine the brightest.

The second situation is about a car coming towards the pedestrian/cyclist. This means the pedestrian/cyclist is looking into the headlights of the car. It is important in this situation that the pedestrian/cyclist is not blinded by the lights of the car and the driver of the car sees the pedestrian/cyclist clearly. This is because the pedestrian/cyclist and driver have to pass each other safely on the street. In the article ‘The effects of dimmable road lighting: A comparison of measured and perceived visibility’ it is stated that the visibility is not much dependent on the amount of light but mostly on the contrast. This means that if the light is coming towards them, the brightness of the streetlight has to be higher than when a car is heading in the same direction, to have a good visibility . Therefore the streetlights should shine brighter in the preference of the cyclist.

In the last situation, the pedestrian/cyclist wants to cross the street. This means that the pedestrian/cyclist has to see whether there is other traffic passing by. If the pedestrian/cyclist is looking in the direction where a car is coming from, they'll gets blinded by the car's headlights, just like in the second situation. However, this time it is really important that the pedestrian/cyclist can see if there is more traffic coming. To make sure the pedestrian/cyclist can see this, the streetlights have to shine brighter than in the second situation.

Drivers of cars

For the drivers, the most important thing is that they can see if there is other traffic coming so they can give priority to traffic that is coming from the right and they can just simply stop in time. As stated in the description of the street the cars are allowed to drive 30 [km/h]. This means that they have a stop distance of 5,3 meters including response time . So at the bare minimum, the driver has to see around 10 meters ahead. The average distance a light of a car can light up is 60 meter, in front of the car, with a low beam . This means that the car's headlights are good enough to see the cyclist on time and the driver does not need the streetlights to be on. So the SMART streetlights should not respond when just a car is driving on the street.

Example

For example, when a car is driving on the street and a cyclist is cycling the other way, how bright should the streetlight light up? For the driver of the car, the streetlights should stay at the same percentage as normal (40 percent). But for the cyclist, the streetlights should shine brighter, because it is looking into the headlights of the car. This means that the streetlights will shine brighter and will be on for 60 percent. After the car and cyclist pass by the streetlight will go back to their 'normal' brightness.

Modeling the control system

Based on the scenarios discussed above, we determined a series of behaviors of the system according to various sensing results. For the model where every single streetlight has a sensor, some assumptions have to made to detect whether a person or a car is passing by. The model works as follow. When the sensor detects something a timer is started. If it is a car passing by, the car will be out of the sensors range after two seconds. To say this, two assumptions were made:

• The car is driving 30 km/h.
• The sensors range of detecting is a radius of 8 meters.

So with the following calculation, the 2 seconds can be calculated: 16/(30/3.6) = 2 seconds.

So if the sensor is still detecting something after the timer is on for 2 seconds, it is a pedestrian or cyclist passing by. Otherwise, it will be a car. If a car is passing by noting should happen with the illumination of the streetlight. If a pedestrian/cyclist is passing by the illumination should slowly go up. After the streetlight is at 40% it should stay on for 30 seconds and then switch off. However if during those 30 seconds the sensors detect something new the streetlight should stay on for another 30 seconds.

For the model with two streetlights, they have to communicate to make it different from the model explained before. For this model, a new assumption is made and that is that a pedestrian is walking 5 km/h. This new system works almost the same is the system with every single streetlight having a sensor. However know the next streetlight should go on when the pedestrian/cyclist is not yet in the range of the sensor, of this second streetlight. To be able to still do this the first streetlights gives a signal to the second one after the timer is on for 6 seconds (This means that the pedestrian is directly under the first streetlight). The second streetlight receives this single and the illumination of this streetlight will go up. So there will be light in front and behind the pedestrian/cyclist.

We built a prototype of this model using UPPAAL which is an integrated tool environment for modeling, simulation and verification of real-time systems, developed jointly by Basic Research in Computer Science at Aalborg University in Denmark and the Department of Information Technology at Uppsala University in Sweden.

Model of the light control system

Simulation

A simulation is being constructed, to show behavior in different scenarios. Realistic dimensions are used to make an accurate representation of reality. The program that is used to make the simulation is called CIF and is developed by the TU/e. In adition to giving a visual representation of the behaviour of the system, it will also give an indication of the visibility of the different road users. Some research needs to be done on visibility however, before this can be implemented.