Stories of science from the lab

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lab stories of science

Stories of Science from the lab

Colophon Stories of Science are made by the Communication team of the Faculty of Civil Engineering & Geosciences. This booklet contains lab stories to show past or present research projects using the lab facilities. Do let us know if you see any new or interesting experiments that you think should be shared. Find all the stories at: ceg.tudelft.nl/storiesofscience Contact: communication-citg@tudelft.nl Design and lay-out: Chris Versteeg / Projekt C Authors: Annelies de Bakker, Karlijn Spoor, Pieke Hoekstra, Marietje BĂśhmer, Marieke Hopley, Wendy Dallinga, Bjinse Dankert Photography: Frank AuperlĂŠ

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Foreword Bert Geerken Dean Faculty of Civil Engineering & Geosciences

This booklet presents a collection of stories from our labs illustrating past and present research projects at TU Delft’s Faculty of Civil Engineering and Geosciences. It is in labs that many of our scientists conduct their (PhD) research as well as contract research for (international) governmental institutes, companies and fellow-research centres.

Some of our facilities are unique and state-of-the-art. Our labs are home to large-scale experiments involving concrete pylons, steel bridge decks, ocean currents, earthquake simulations, recycling techniques and much more. On entering a lab you may be welcomed by the sound of water rushing down flumes or, sometimes, the ear-splitting noise of breaking concrete collapsing under controlled pressure loads.

Every experiment in our labs is aimed at improving our understanding of reality, from the actual behaviour of rivers, seas, constructions, subsurface or dikes to many other aspects of the world around us that we don’t yet fully understand.

Read all about our researchers at work as they simulate reality and validate their models and prepare to be amazed by the innovative character and impressive scale and sounds of many of the experiments!

For more Stories of Science please visit our website.

lab stories of science

www.ceg.tudelft.nl/storiesofscience

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Marker Wadden – building wetlands with soft mud

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10,000 plastic plants in the Waterlab

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Follow the pretty pebbles

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Working together with worms

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Drinking water quality after Thermal Energy Recovery

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A chlorine-free pool

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Reducing arsenic levels in drinking water

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Testing the Rails

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The strength of glass

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How strong are houses in Groningen?

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A cement free concrete canoe

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The bike lane as a laboratory

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The data that will get you from A to B

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Selfdriving Twizy

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Selfdriving WEPod

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Navigating the motorways with pinpoint accuracy

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Mangroves caught in the middle

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Mangroves caught in the middle

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Mangroves caught in the middle In a channel at TU Delft’s Water lab a stream of purple-tinted water makes its way past thousands of small wooden pegs. The water was dyed by PhD-candidate Son Truong Hong, who is closely observing the flow with an empty bottle of paint in his hands. This test forms part of his research into the importance of the mangrove forests in the Mekong Delta estuaries. Son is fascinated by the tangled roots of these extraordinary trees. What is the mangrove’s role in preventing river bank erosion? And, most crucially, how much of the mangrove forests needs to remain to support a healthy ecosystem?

No place to go

brackish water on one side, and agriculture, de-

Tropical mangrove forests grow in coastal

forestation and spatial blocking on the other. This

habitats where water meets land. Son, who

is my interpretation of “squeeze”. What I want to

is from Vietnam, is looking specifically at the

establish is the critical size the forests needs to

mangroves in the Mekong Delta estuaries in his

be in order to stay healthy.”

homeland. This is where fresh and salt water mingle and the tides of the sea can be observed.

Preventing erosion

But the mangrove forests, which grow partly in

According to Son there are important reasons for

the water and on land, are in trouble, say Son and

maintaining the presence of the mangrove forests

his colleagues. Rising sea levels mean the roots

in the Mekong estuaries. Mangrove forests play

of the mangroves are immersed in water too long

a part in protecting the river banks from erosion.

or too deeply at high tide. The water pushes the

On the basis of aerial photographs of the Mekong

mangroves into a narrower and narrower fringe

Delta Son could see that in sites where man-

to finally disappear totally. “This phenomenon we

groves had been felled river banks were eroding

call the ‘mangrove squeeze’ and it is the starting

at a much faster rate. “There is a connection

point for my research. I use a broader sense of

between mangroves and erosion but what exactly

squeeze, however, than in the context of sea-level

is it?”, Son asked himself. He found that the

rise impact alone.”

massive, partly submerged, roots of the trees are efficiently damping the flow of the river and so

Son explains that more factors are threatening

lessen its eroding impact on the river bank during

the forest. The local population is felling trees

high tides.

to make room for fish farms which have been pro-

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liferating in recent years. ‘The mangrove forests in

Roots not only help prevent erosion of river

the Mekong estuaries have no place to go, ‘Son

banks, they also help to strengthen them by

explains. ’They are caught between too much

catching the fine particles of sediment (which can

include nutrients) carried by the river which are

that in order to maintain a healthy ecosystem

then deposited. “This is very useful for combatting

and strong river banks a strip of mangrove forest

the effects of rising sea levels,” Son states. But

needs to have a width of at least 80 meters. He

the question is how wide the strip of forest should

is now testing his hypothesis in the Water lab

be to optimise this effect. And which mechanisms

flume. In a series of tests Son positions a number

take place at the interface of the forest and the

of wooden pegs representing the mangrove roots

adjacent river channel?

at varying distances from each other. Water runs of cameras, sensors and a type of scoop net he

There is more. Apart from preventing erosion

measures the rate at which the water slows down

mangrove forests also sustain flora and fau-

at each level of density. That also tells him if ero-

na. The swamps formed by mangroves are an

sion is prevented or lessened. But the purple dye

important habitat for many species of fish, shrimp

test is his favourite. “The purple stuff helps to see

and bird. The trees offer protection but, even

the penetration of silt and nutrient carrying water

more importantly, they provide food as nutri-

in the network of roots in the swamp.” The test

ent-rich sediment adheres itself to their roots. ‘If

reveals a very large eddy structure (or whirlpool)

the encroachment on the forests continues, the

that forms and spirals in a certain way along the

ecosystem will not be able to sustain itself,’ Son

wooden pegs. “This specific way in which the

warns. ‘We want to be able to tell people how

wooden pegs impact how the water flows, con-

much of the forest needs to remain in order for it

tributes in a large part to the exchange processes

to continue to exist. That is why in my experiment

between the mangrove roots and the river current.

I want to find out how the river and the mangrove

I think I will call this type of movement a ‘cycling

forest exchange sediment and nutrients.

motion’ in my future papers. And yes, it looks really pretty!”

The experiment On the basis of existing data, satellite photos and

And with that Son grabs a fresh bottle of dye and

a Delft3D model Son formulated the hypothesis

puts his wellies on for another round of testing.

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though the channel along the roots. With the help A healthy ecosystem

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Marker Wadden: Building wetlands with soft mud

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Marker Wadden: Building wetlands with soft mud Markermeer, a manmade lake in the North of Holland, functions as a freshwater reservoir and a buffer against floodwaters and droughts. Its 680 sq kilometres have a predominantly soft mud layer at the lake’s bed. Due to its shallow depth of 3 to 5 meters, the wind-induced waves are strong enough already at low wind speeds, to move the soft mud through the water. The dam, connecting Lelystad and Enkhuizen, add to the trapped sediment causing turbidity. The severe turbidity hampers light penetration through water and the overall ecological development. Natuurmonumenten and its consortium partners (Boskalis, Van Oord, Royal Haskoningh DHV, Deltares and Alterra) are committed to bringing life back to this lake. By removing the mud layer from the lake’s bed and re-using the soft sediment to build wetlands, they are expecting to transform a part of the lake into the new nature reserve ‘Marker Wadden’.

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PhD students Maria Barciela Rial (TU Delft)

soft mud all around the world. Mud is abundant-

and Rémon Saaltink (University of Utrecht) are

ly available worldwide. It consists of water, fine

excited to be part of this large scientific project:

clay and very small particles of organic matter.

“It is like building wetlands with low fat yoghurt.

This makes handling this soft material complex

To overcome the challenges associated with the

because both physical and chemical processes

building material, we use natural processes that

play a role. Strengthening a mud layer by artificial

are freely available and that will accelerate this

drainage is costly. Rémon and Maria emphasise

ecosystem development. We do not add any arti-

that nature provides a drainage service also:

ficial elements such as constructed walls.” Rémon

“Plants extract water from the soil through their

and Maria study the physical and ecological

roots.” Plants that can grow on soft mud influ-

processes that take place that control the consol-

ence the sediment property and vice versa. The

idation of fresh mud. The combination of Maria’s

two researchers have an innovative solution for

in-depth knowledge on mud sediment physics

converting the soft material into a stable foun-

and Rémon’s specialism on the two-way interac-

dation for wetlands: “Our joint research focuses

tion between plants and soil holds the promise of

on how we can use this feedback mechanism

jointly coming up with very valuable insights that

of plants for mud consolidation. We expect that

may lead to a model for building wetlands with

reed (Phragmites australis), a common species

growing naturally at the Markermeer, can function as the ecological engineering species to enhance consolidation.” For stabilising the sediment within this project, it is important that the reed is growing fast. Because the vegetation also attenuates waves and hence, prevents erosion.

“To study the workings of this free service of nature, we have designed a lab experiment to measure the amount of water plants take up from the sediment and relate this to pressure differences in the sediment column. As roots grow, pressure differences in the column are expected to change through time. Therefore, we want to relate the water loss, the pressure difference per depth to the amount of roots in the soil, as an indicator of the capacity of sediment consolidation.” For

with and without reed. We aim to get these

this, Maria and Rémon are conducting a small-

entangled factors moulded into reliable modelling,

scale pilot in the TU Delft Waterlab. “Our research

that incorporates factors as the consolidation

requires highly technical sensors and measure-

of wetlands parts with and also without growing

ment systems on the pressure of water in the soil

reed. We intend to upscale the model to predict

and release of water. The highly-trained Waterlab

the consolidation time at the Marker Wadden.”

technicians and the TU Delft workshop DEMO built the columns and the measuring systems that

“With this experiment, we hope to showcase

were required. With these innovative adapted

the eco-engineering capabilities of reed for

pressure sensors, this unprecedented experiment

consolidating soft mud.” Considering soft mud

has become possible.”

as building material for wetland construction is

To have a clear indication of root growth alone,

c. 10.000 ha of wetland in the near future, repre-

the lab experiment excludes influences such as

sents one of the first projects in the world using

temperature differences, light hours and climate

mud as a filling material and the first one doing it

that takes place outside in the wild. “We installed

under the Building with Nature approach instead

large columns (130cm) and planted three reed

of using traditional engineering practices. The

seedlings in each column.” Each month, Rémon

ultimate goal objective is that the wetlands have

selects one column and he determines the

such a solid sediment, that goose can walk on it,

amount of root biomass and root surface area per

and various plants can thrive. So that the Marker

unit of depth (f.e. from 0-10 cm, from 10 –20 cm,

Wadden turn into a birds paradise, based on mud

from 20-30cm and so on). This leads to a depth

that was initially as soft as yoghurt.

profile of roots through time.“ This will enable us to design a model that makes it possible to predict how long it will take for soft mud to consolidate

lab stories of science

unprecedented. The Marker Wadden, comprising

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10,000 plastic plants in the waterlab

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10,000 plastic plants in the waterlab A river flows through the main channel of the waterlab full of little, green plastic plants. PhD Andrés Vargas uses this set up to study how rivers behave. What determines their shape? If you know that, you can arrive at better decisions for the cities and land located along the river. For example, where is the best place to build a bridge?

And what effect does that have on the river and the surrounding land?

Vegetation’s role

developed as well as erosion on the other side.

The two principal changes that determine the

During Phase 2 we did the same again, but after

shape of a river are the bed level changes and

a week we placed vegetation along the flood-

the processes on the banks. When a river mean-

plains. During Phase 3 we repeated the entire

ders, the banks erode on one side and extend on

process, this time not only putting vegetation on

the other. There are currently multiple models that

the flood plains, but also on the sediment bars.”

use the strength of the flow to calculate how the

During every phase Vargas threw small, black

banks erode. “But problems arise when trying to

squares into the river that could be detected by a

calculate their extension as there are no models

photo camera, allowing him to measure how the

for this. It is often assumed that the land that

water flowed.

erodes from one bank, expands the other. But it isn’t that simple due to, among other things, the

Lots of work, lots of fun

role of vegetation in the process and that is what

Vargas opted for small plastic plants to study the

my research is on. I want to know which role

role of vegetation. “We put 10,000 in the main

vegetation plays in the development of river-

channel. That was really fun, but an awful lot of

banks.”

work. We did it in hour-long planting shifts. It was down and this led to cramping arms.” However, it

To discover how this works and then model it,

was worth it. “We collected unique data! Else-

Vargas started his experiment at the lab with a

where this has only been studied in miniature,

straight, narrow, elongated channel in the large

with solely qualitative results. Now, for the first

flume. He created scenarios with and without

time, we have quantitative data.”

vegetation. “During Phase 1 we subsequently allowed the water to flow for 90 hours: sandbanks

lab stories of science

impossible to last any long as you were upside The experiment

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lab stories of science

Follow the pretty pebbles

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Follow the pretty pebbles Rivers meander: it’s what they do. They make their way through the landscape twisting and turning as they flow. In the Netherlands a meandering river has become a rarity. ‘Many rivers worldwide have been ‘humanised’, says Victor Chavarrias who is researching rivers, with the Rhine as his case study. ‘200 years ago the Rhine meandered strongly. That made life in the floodplain dangerous and the transportation of goods very inefficient. To overcome these difficulties in the 19th century they started cutting the bends and narrowing the river with the construction of groynes.

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One of the consequences of these interventions

‘The river has also been used as a source of

is that the river bed degrades, which is problema-

sand by companies, which has made the problem

tic for instance, for farming, or for the stability of

worse. Taking sand from the river is no longer

foundations of fixed structures, such as bridges.

allowed unless it is put back in other parts of the

what really happens provides him with the data

sand. ‘But if we add sediment what will happen

he needs to adapt the models. The sediment

to the Rhine in 5, 10 or 100 years? 200 years

consists of differently sized material and that is

ago the consequences of straightening the river

why Chavarrias has colour-coded similarly sized

weren’t properly understood. We want to make

pebbles. ‘I used water resistant paint of course.’

sure we don’t make the same mistakes. That’s

During the experiment he takes photographs

why it’s important to be able to predict how the

of the bed surface. ‘I feed the images into a

river will behave when we intervene. That will give

programme which can analyse the numbers of

us answers to questions such as: how much sand

identically coloured pebbles. That saves me from

do we need to deposit? Where should we put it?

having to extract and sieve samples and allows

How often do we need to repeat the process? And

me to take measurements while the experiment is

where does the sand end up?’

running.’ It is not only the new scientific data that

There are models which predict the flow of water

excites Chavarrias but also its application. ‘The

and sediment. ‘But in this case we also need mo-

institutions who are paying for this research, such

dels for the movement of mixtures of sediment of

as Rijkswaterstaat, will at some point in the future

different sizes. There are models that do this but

get to work using my research!’

they are not always suitable.’ And that is where Chavarrias’ research begins.

At the lab he tries to simulate situations in which the present models don’t work. Watching

lab stories of science

river.’ The solution seems simple: just add more

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Working together with worms

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Working together with worms Getting the best out of nature is what drives biotechnology scientist Steef de Valk. In the Waterlab of TU Delft he is researching the way tubifex worms process sludge. Knowing more about how they manage to decompose the sludge so efficiently, can contribute to a better purification process in waste water treatment plants.

“There is no need for genetic manipulation.

and circumstances in how to apply it best have

Nature has it all”, says Steef enthusiastically, “you

changed.” Sludge is the ‘by-product’ of waste wa-

need to find the best way of working together

ter treatment. It is a mixture of microbial biomass

with nature to get the best out of it. It. If you can

and non- degraded organic compounds that are

create the right environment, you can make things

left after the process. Originally, sludge was used

prosper and use them to your advantage.”

as a fertilizer in agriculture. When laws prevented farmers from using it on their fields, the focus

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“There have always been discussions about the

shifted to more efficient ways to treat sludge in

way we can use sludge to benefit our society”,

waste water treatment plants . This is where the

Steef continues, “However, over time insights

worms come in. The biological processes in such

a treatment plant turn part of the organic com-

bacteria, it is an even bigger task to detect which

pounds in the waste water into biomass, which is

ones out of thousands species are involved in the

used as an energy source for biogas production.

decomposition process. Once we understand the

During biogas production the amount of waste is

process, we could replicate it on a larger scale.

reduced by 30%. The rest is shipped off and burnt

Even though worms love the tough environment

in incinerators. Transporting waste is costly. By

of sludge, they are fragile organisms. It would

introducing worms to the treatment process, an

be more reliable to be able to copy the digestive

additional 30% of the sludge can be reduced. By

mechanism.”

putting worms in an environment they thrive in, that is contaminated sludge, we are working to-

“However, the demands of society keep shifting”,

gether with them. The worm process has a higher

Steef concludes. “Reducing sludge for the sake

sludge reduction, thus reducing the amount of

of getting rid of it does not seem the be a valid

waste to be transported and burnt.

reason anymore. Sludge is more and more seen sludge differently, for instance with the use of

the sludge so efficiently? Steef wants to know.

enzymes, it can also be turned into fatty acids,

It is most likely a combination of bacteria at

which can be used as precursors in the produc-

work and the enzymes that the worm produces.

tion of a wide range of materials. Whichever

Another example, this time on a microbiological

way developments go, the worms have shown

level, of how a good match works well together

that there are different ways to deal with organic

in nature. “Finding out what the balance between

matter.”

this cooperation is, is the hard part. If the worm plays the major part, you need to find out which enzymes are used. If it is mainly due to the

lab stories of science

as a resource instead of a waste. By processing What mechanism are the worms using to digest

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lab stories of science

Drinking water quality after Thermal Energy Recovery

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Drinking water quality after Thermal Energy Recovery Water companies are keen to use cold from drinking water as a source of energy for cooling purposes, such as cooling houses. This technique, called Thermal Energy Recovery, companies wish to operate climate friendly and turn water distribution networks into a renewable energy resource. But if the drinking water loses its chill, will it still be fit for human consumption? And what about the microbiological quality of the water? That is what PhD candidate Jawairia Imtiaz Ahmad is trying to find out at TU Delft’s Waterlab.

Pipes and biofilm

Clean drinking water

Jawairia and her colleagues at the Waterlab have

For Jawairia clean drinking water is not something

built a small drinking water distribution network

she takes for granted. ‘In my homeland, Pakistan,

of grey PVC pipes to mimic the real distribution

the water is not as clean as it is here. Sometimes

network situation. Within this controlled testing

sewage water ends up in drinking water. In Paki-

environment, the water is heated to a variety of

stan chlorine is used to purify water. When I heard

temperatures with a maximum of 25 degrees Cel-

that European water companies don’t need to

sius. Jawairia then measures the microbiological

resort to chlorine I became interested. I wondered

quality of the water under different temperatures

how small countries could provide clean drinking

and under different hydrodynamic conditions of

water when my own country couldn’t. People

cold recovery. ‘In the Netherlands drinking water

even drink water from the tap here in the Nether-

in the distribution network can have a maximum

lands. That would be unthinkable in Pakistan.’

temperature of 15 degrees Celsius because that is deemed a safe limit. But that has never been

Thermal Energy Recovery

researched properly.’ Jawairia not only looks at

In order to continue to be able to drink water

the water flowing through the pipes, she also

from the tap, it is important to know how using

looks at the formation of biofilm, a slimy layer of

the cold from drinking water for cooling purposes

bacteria, on the walls of the pipes. ‘Biofilm often

impacts on its quality. How does it work? ‘We use

contains micro-organisms that can endanger

a system called Thermal Energy Recovery. This

health. Higher temperatures will speed up the

basically means having cold drinking water flow

build-up of biofilm which can then become a

through one pipe, and warmer ground water in

source of, for instance, legionella.’

another adjacent pipe. The two flows exchange heat and cold in the so-called heat exchanger.

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ature to which we can recover cold from drinking

the exchange and flows back to an Aquifer Ther-

water and still have clean, microbiologically safe

mal Energy Storage (ATES) reservoirs. This water

water. I also want to know if the materials used in

is later used for cooling buildings. Once there,

the heat exchanger influence the microbiology of

less energy is needed to cool the water because

water. With this knowledge we can advise water

it is cooler already. ‘But what we see in the pipe of

companies about the maximum safe temperature

drinking water after heat exchange are fluctuating

limit to provide clean drinking water along with

water temperatures. The temperature has gone

energy recovery from it. Hopefully this can help

up. I look at the way higher temperatures in the

water companies in Europe to use the drinking

distribution network affect the quality of the water

water distribution network as a renewable energy

people drink.’

resource.

Advice Jawairia’s research is also helping Dutch water companies: ‘I want to know the maximum temper-

lab stories of science

The ground water becomes cooler as a result of

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A chlorine free pool

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A chlorine free pool Pool water is usually disinfected using chlorine-based products, such as hypochlorite, to wipe out all micro-organisms. Unfortunately, hypochlorite also reacts with other pollutants in the water, such as sweat and urine, to release disinfection by-products.

These by-products may be harmful to health and can cause skin irritation and red eyes.

The DIPool project of Marjolein Peters and Maarten Keuten looks at how the formation of harmful disinfection by-products can be counteracted, either by reducing the contamination of the water or by using less or no hypochlorite. The ultimate goal is to develop a chlorine-free pool based on UV disinfection.

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to a multitude of bacteria. To prevent biofilm from

The contamination of pool water can be reduced

forming, Peters looked into the use of alternative

considerably if swimmers improve their hygiene

materials, such as stainless steel and plastics.

behaviour. The initial contaminant input – dirt on

She is also investigating the best way of removing

the skin – comprises about 30% of the total con-

biofilm using a robotic pool cleaner.

taminant input and can be reduced by a one-

Any remaining micro-organisms can be removed

minute pre-swim shower. Persuading swimmers

during the purification process. DIPool water

not to pee in the pool would bring contamination

purification is based on ultrafiltration and UV

down by another 30%. Simply by being cleaner,

disinfection. Lab tests showed that the microbio-

swimmers can reduce contamination and harmful

logical quality of the water was comparable to that

disinfection by-products by a whopping 60%.

of chlorinated pool water, with the added advantage that the DIPool purification method does not

Micro-organisms

produce harmful disinfection by-products. A pilot

If no hypochlorite is used at all, micro-organisms

will have to determine whether or not the DIPool

will survive and form into biofilms on the walls of

concept will be as successful in practice as it is in

the pool. Biofilms are slimy to the touch and home

the lab.

lab stories of science

Hygiene

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Reducing arsenic levels in drinking water

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Reducing arsenic levels in drinking water Arsenic, an element which occurs naturally in the environment, is present in the soil and groundwater of several areas in the Netherlands. According to the World Health Organisation (WHO) the presence of large concentrations of arsenic poses a threat to public health. While concentrations in drinking water are within the present critical WHO values, guidelines regarding arsenic content may, in future, become more stringent.

When this happens Dutch water companies will

Reactor

have to adapt their water treatment plants in order

That is why Jink is optimising a chemical process

to comply with the new norm. Jink is studying

which removes arsenic effectively and can be

effective ways of removing arsenic from drinking

fitted to an existing water purification system. He

water in TU Delft’s Waterlab so the quality of

is developing a reactor which can remove arsenic

Dutch drinking water will continue to comply with

from different areas in the country. ‘The compo-

the norm.

sition of water varies from place to place. In the concentrations of arsenic in the groundwater. That

water. Costs and benefits have to weighed care-

is why no two arsenic removal processes are the

fully as the present techniques are expensive,

same.’ At the Waterlab Jink studies the various

or require the use of heavy chemicals which are

chemical reactions in sample beakers. He also

a danger in themselves. Jink favours a method

does fieldwork at various water treatment plants

which doesn’t require additional building or the

around the country.

use of heavy chemicals. ‘Adding chlorine could be a solution but that is not what we want to do.’

lab stories of science

Netherlands alone each area has slightly different There are several ways of removing arsenic from

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lab stories of science

Testing the Rails

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Testing the Rails One mouse click and the iron cross behind the glass groans to life.

This is a new test installation to research wear on railway material.

With nearly 100 h.p., the hefty engine can ac-

Dr Zili Li watches the installation proudly. He

celerate the 4-metre-wide cross to 1 revolution

funded the million euros required for the test

per second. That is a fairly impressive speed,

installation with work conducted by the railway

certainly when you are standing right next to the

engineering laboratory for external clients over

spectacle. Four times a second, a mini railway

the past decade. “A week on the test track is

wheel races over the mini railway in the basement

comparable to a year on the railway network,”

of the building housing the Faculty of Civil Engi-

explains Li. Every 10 seconds, 40 axles crash

neering and Geosciences.

over each point of the circular rail – equivalent to a train every ten seconds. The speed on the test

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descriptions. Measurements that can be effec-

achieved by a TGV train. Spring tension can be

tively reproduced are necessary in order to test

used to increase the force exerted on the wheels.

mathematical models. A mathematical model for

And to accelerate wear and fatigue even further,

rail wear and fatigue needs to link force and ten-

the wheels can be driven forward and braked,

sion on the one hand with material composition

corresponding to the additional wear and fatigue

and microstructures on the other. A valid model

on wheels and rails under a locomotive.

could potentially be used to design better quality

During the tests, wear on the wheels is measured

materials that are less susceptible to wear and fa-

down to the micrometre. The threedimensional

tigue. Conversely, it is conceivable that the design

acceleration measured in the bearings corre-

of the rail and wheel could be improved, meaning

sponds to the measurements conducted by the

that the current materials last longer.

TU Delft ‘measurement train’ – a reallife carriage that travels on the Dutch railway network. The

Whichever route is ultimately chosen, all im-

laboratory situation and reality are therefore com-

provements begin with thorough and reproducible

parable. Li really comes into his own when asked

measurements. And that is something that recent-

about potential applications. Wear and fatigue

ly became possible in a basement in Delft.

measurements form the essence of theoretical

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track is also equivalent to the 280 km/h speed

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The strength of glass

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The strength of glass Glass breaks, doesn’t it? It’s wonderfully suited to creating light effects and a sense of spaciousness. But can it be used in a load-bearing capacity, for instance in walls, bridges and pillars? The answer is yes: under pressure glass becomes incredibly tough. TU Delft’s Stevin II laboratory is home to one of the few teams in the world doing research into the suitability of glass as a building material. Here PhDs and professors are finding ways to make glass in construction strong and safe without compromising on transparency.

Cast glass

size. The architect’s way around it was to opt

‘Right, we’ve got our space suits on, let’s open the

for glass bricks. Promotors Fred Veer and ‘glass

glass furnace!’ Friends, fellow-Greeks and PhDs

professor’ Rob Nijsse invited Faidra and Tele to

Telesilla Bristogianni and Faidra Oikonomopoulou

look into the design and manufacturing process of

are at the Civil Engineering and Geosciences

the bricks and the construction of a glass façade

glass lab, decked out in shiny metallic protective

to see if it could be done. After all it would have to

clothing complete with masks and giant gloves.

hold up it’s own weight and the windload.

The furnace has been heated to a temperature of 1000 degrees Celsius and Tele and Faidra are

The challenge was to make the bricks and

ready for the next experiment. They are heating

the structure itself strong, vandal proof and as

shards of glass placed on top of an earthenware

transparent as possible. ‘We had to think of lots of

pot. The glass melts and leaks into the pot. Via

ways of testing this,’ Faidra explains. ‘How do you

a hole in the bottom of the pot the molten glass

determine the strength of a glass brick or wall?

flows evenly into a mould. Then the furnace is

How do we make the bricks and how do we cool

left to cool down slowly. This allows the glass to

them down in a way that keeps them transpa-

harden in controlled manner so it won’t crack at

rent? And what do we use to stick them together?’

the centre. The results of previous experiments

Cement was out because it would compromise

are strewn around the lab: bricks, lego bricks,

transparency. Still, they had to find something to

pillars and cylinders of cast glass.

turn the separate bricks into a strong monolithic

Transparent bricks

parent glue which can withstand the changes in

It all started with the Crystal House in Amster-

temperatures a structure like this is subject to.

structure. The solution they hit upon was a trans-

dam’s P.C. Hooftstraat. Chanel planned to open

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a flagship store there and wanted a glass façade.

Vandal proof

But the building is a monument and has to meet

Once the experimental glass wall was up it could

certain requirements. One of the requirements is

be tested. In order to determine its strength

that the façade be made up of bricks of a certain

Faidra was allowed to release her inner vandal

and hit it as hard as she could using a hammer.

there’s a psychological aspect to consider as well.

While some of the bricks shattered the structure

A ceiling that rests on two transparent pillars that

itself remained intact. The building of the façade

are barely visible can freak people out: that ceiling

could begin. Faidra and Tele singlehandedly built

isn’t held up by anything!’ That is why the duo

the first 1.5 meters of the façade. ‘We were laying

is making the columns slightly less transparent

bricks at the construction site from 7.30 in the

than the bricks used for the Crystal House. Faidra

morning to 7.30 at night to show the workmen

developed a new version of the bundles column,

how it was done,’ says Tele. ‘It was tough but a

consisting of 7 transparent glass rods that are

good way of learning to manage a big project.’

joined and glued together. This causes the light in the rods to refract making the pillars easy to dis-

Glass columns

tinguish. ‘And it has the added bonus of prevent-

Back at the lab the research group is building on

ing people from bumping into them.’

the new ideas generated by the Crystal House project. Faidra and Tele are studying the manu-

What next? The two girls would love to replace

facture of glass columns. Pillars or columns made

one of the pillars of the Berlagezaal with a glass

of concrete break up a space and obstruct the

one. ‘Then visitors would no longer mind being

view, which makes them the pet hatred of many

stuck behind a pillar!’ One of their other main am-

architects. They are a necessary evil, however,

bitions is the project ‘Restoration by Glass’. Here

because they carry the weight of a roof or ceiling.

they want to restore historic damaged monuments

But could glass be used instead?

by replacing the missing components with glass.

‘People are not completely convinced that glass

is to make sure the oven is set correctly to slowly

is actually strong enough,’. Tele says. ‘We can

cool down the glass component inside. Time to

show them the scientific proof of course but

take off the extremely warm masks.

lab stories of science

But for the remains of this day, all that’s left to do

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lab stories of science

How strong are houses in Groningen?

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How strong are houses in Groningen?

There’s a house in the Stevinlab. Life-sized, built by bricklayers from the north with the mortar and calcium silicate they use in Groningen. The walls are covered in sensors, there are cameras everywhere and an awful lot of wiring. Because the house is shaken back and forth very slowly. A large group of scientists from across the Faculty of Civil Engineering have crowded around a monitor that displays the data in real time. They are all collaborating to help answer a question that is important to those living in the Groningen earthquake zone: are houses there going to withstand the next quake?

The tests are being conducted at the behest of

rare in the Netherlands.” That has all changed

the Nederlandse Aardolie Maatschappij (NAM

with the earthquakes in Groningen. “The models

- Netherlands oil and gas company). It wants

we used for calculations were always based on

to know how resilient houses in Groningen

stationary houses. Now we suddenly have to take

are against earthquakes. Which homes might

the earth shaking from side to side into account.

collapse? Which ones need shoring up? This is

This demands new models.”

why NAM has set up an extensive research programme and this experiment is an important part

Countless tests have been carried out to this

of that. The results of the various studies will be

end. Tests on materials from affected homes in

compiled and published over the course of 2016.

Groningen. From individual stones to entire walls that have been copied. And now, for the first time,

“Where will the first tear develop according

a whole house. “The data from the prior tests

to your calculations?” project leader Ton van

allowed us to model the behaviour of a home. We

Beek asks one of his colleagues at the lab.

are now, he points at the screen, comparing those

“Somewhere at the top, in the middle,” the latter

calculations to the results of the tests. Are they

answers. Van Beek explains: “Whether a house

correct? And why or why not? This will allow us to

is safe or not is determined on the basis of the

discover why what happens.”

so-called Dutch Practical Guideline for Earth-

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quake-proof construction. In the Netherlands, ex-

The house in the Stevinlab was built recently

isting brick structures are primarily wind resistant.

by bricklayers from Groningen using bricks and

They were never structured to withstand earth-

mortar from that province. Everything has the

quakes because, until recently, earthquakes were

typical material properties of a typical 1970s

terraced home of the type often encountered in

in Europe. Natural earthquakes are caused by

Groningen’s earthquake zone. “A test such as this

tectonic plates shifting and have long aftershocks.

should preferably be conducted using old materi-

Those in Groningen consist of a single, very sub-

als. Obviously, people in Groningen would prefer

stantial shift. “These deviant quakes together with

us not to knock their home’s down. After 600 tests

the wall characteristics mean there is a scientific

using old brickwork we know exactly what the

blind spot in this respect.”

‘new house’ has to be like.” enough to construct an entire house in. The Ste-

centre for earthquake research in Pavia, Italy.

vinlab is the largest of its kind in the Netherlands.

NAM also had a large number of tests carried

“Moreover, the facility has all the specific technical

out there. “A lot of the tests are conducted twice,

staff required. Another major advantage is that

once in Italy and once here. This helps us learn

the calculators and the experiment reside in the

from one another. This is basically virgin territory.

same building. One minute you have mortar on

We have no knowledge of earthquakes’ effects on

your fingers, the next you are calculating what the

typical Dutch houses with 10 cm thick walls.” This

experiment generated.”

is the preferred construction method on the weak, soggy Dutch soil. You built light to avoid subsid-

Suddenly three people dash towards the house,

ence. “The Italians were flabbergasted when they

cameras at the ready. The first tear has appeared,

saw our thin walls. Their walls are at least 30 cm

at bottom left.

thick.” Another factor is that the earthquakes typical to Groningen are unlike other quakes

lab stories of science

Few laboratories in the Netherlands are large TU Delft cooperates closely with Eucentre, the

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lab stories of science

A cement free concrete canoe

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A cement free concrete canoe A drum roll sounds in the Stevin II laboratory. 20 students and researchers in blue lab coats and safety shoes are gathered around a 6 meter long canoe mould. They have 15 minutes to properly distribute the mixture in the mould, tamp it down and do the finishing. ‘Faster!’ shouts researcher Marija Nedeljković and the rhythm of the patting hands accelerates. Then Arthur, the leader of the student team, comes with a large plastic sheet to cover the mould. The first cement free concrete canoe has been finished.

This canoe is special for researchers Marija

massive scale. The total CO2 footprint per one ton

Nedeljković, Mladena Luković and Ye Guang, as

of Portland cement is almost 1:1, meaning that for

well as for the U-base fraternity’s students. After a

each ton of Portland cement produced, one ton of

few years absence, the frat can again take part in

CO2 is emitted.

the much-loved concrete canoe race in Arnhem in

In geopolymer concrete, on the other hand, OPC

late May. This race will be more special than usu-

binder is replaced with a mixture of alkaline and

al as their concrete canoe contains 0% cement.

industrial by-products such as fly ash or blast

So, how does that work?

furnace slag, which are produced during the manufacturing of, for instance, steel. Therefore,

Geopolymer concrete

geopolymer concrete preserves natural resour-

The canoe is made of geopolymer concrete, also

ces, produces less CO2 and allows us to use

known as cement free concrete. This relatively

by-products to develop a sustainable construction

new material with concrete-like properties uses

material and to reduce our carbon footprint.’

only industrial by-products as binder instead of

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the traditional Ordinary Portland Cement (OPC).

From tiles to structures

This makes geopolymer concrete a sustainable

Geopolymer concrete insulates and deals with

alternative to traditional concrete. Marija Nedeljk-

heat better than traditional concrete. It is already

ović, a PhD researcher working at the Microlab of

used to manufacture fire-resistant tiles or walls.

TU Delft, explains. ‘Manufacturing OPC involves

However, the TU Delft researchers want to go

heating limestone in a kiln to form minerals

further. Imagine how beneficial it would be if this

which are grinded afterwards. These processes

sustainable concrete was actually used in the

consume both energy and natural resources on a

construction sector? ‘Concrete is the most utilised

construction material on the planet and is alleged-

group from the Microlab are therefore now wor-

ly responsible for 5% to 8% of all CO2 emissions,’

king on a number of mixtures and are studying

explains Ye Guang, associate professor at the

the durability and time-dependent behaviour of

Microlab. ‘If geopolymer were used worldwide that

geopolymer concrete. Mladena from the Concrete

would be great for the environment.’ Still, a lot has

Structures group is meanwhile looking for ways to

to be done!

use geopolymers in structural applications. This will allow the team to provide recommendations

‘So far we have mostly focused on using geo-

to industry partners so homes can finally be built

polymer concrete in non-structural applications,’

from geopolymer concrete.

is our first attempt at manufacturing a real struc-

Or boats, of course. Concrete canoe race,

ture. To ensure that it can carry loads and stay

here we come!

waterproof we have added fibres to the concrete

During the Concrete Canoe Race of 2016, the

mix. It worked out great and the students stayed

U-base team has won two awards. Their concrete

dry during their first trial ride. The canoe is strong

canoe weighed 250 kilos and was therefore the

enough to race with!’

heaviest canoe of this year’s race. Most importantly, the team was given the award for most

Guidelines for the construction industry

sustainable canoe because of the extraordinary

However, the biggest issue is that there are no

material the canoe was made of.

standards for application of geopolymer concrete and no rules or guidelines for structures made from it. Ye Guang and his Geopolymer research

lab stories of science

explains researcher Mladena Luković. ‘This canoe

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lab stories of science

The bike lane as a laboratory

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The bike lane as a laboratory ‘Ready? GO!’ A white flag drops and two participants in green caps start pedalling their yellow and blue OV bike (bikes obtainable for a small fee from public transport hubs). Participant nr. 4 with a red cap cycles towards the other two from the opposite direction. Cameras above the lane record everything. What will the cyclists do to avoid contact?

56

is much more complex than that of fast traffic.

the TU Delft campus, researcher Yufei Yuan is

How to solve common problems surrounding bike

taking notes. He is trying to work out how cyclists

jams and traffic safety issues where slow and

respond to one another. Will they take evasive

fast traffic meet? Empirical insights, behavioural

action? Do they brake? And how to explain and

theories, models and tools are required to support

predict this behaviour when it comes to the large

planning, design and management.

flows of cyclists that occur on a daily basis in many crowded cities such as Utrecht or Amster-

This experiment is part of ALLEGRO – a TU Delft

dam?

and the AMS institute project. It was financed by the ERC Advanced grant Professor Serge

The data collected will be used to develop a traffic theory for cyclists as this groups behaviour

Hoogendoorn received to this end.

lab stories of science

Next to the temporarily closed bike lane on

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lab stories of science

The data that will get you from A to B

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The data that will get you from A to B Going from A to B by car in the Netherlands does not always turn out to be as smooth a journey as we might wish. In spite of extensive data on driver behaviour and traffic intensity, bottlenecks continue to occur in a number of problem areas. The Delft Integrated Traffic & Travel Laboratory (DiTTLab) is modelling traffic flow to flag up potential snags. To Hans van Lint, initiator and professor of Traffic Simulation & Computing, the DiTTLab is a like playground.

“We’re playing with data layers. Layered data modelling allows us to come up with answers to ‘what if’ questions’ that we couldn’t have found otherwise.”

Data everywhere

dynamics of tailbacks are. “Our work begins and

People are leaving behind data everywhere: GPS

ends with data: first of all we need them to under-

data, mobile data, social media data. Road traffic

stand how things work and then to make models

flow is measured by cameras and inductive loops

which can shine a light on ‘what if’ questions. We

– iron coils which detect movement. The inter-

also need data to check if the models are actually

net is a plentiful source of information too, with

doing what they’re supposed to do i.e. making

open data on car park occupancy rate or public

decent predictions.”

transport timetables. Hans: “In the lab we collate data and develop mathematical models. These

Multilevel approach

models are used to simulate traffic systems. What

The traffic problems modelled by the DiTTLab are

would happen if we removed or added a traffic

approached on a number of levels. At macro level

lane? What if we can persuade people to make

scientists look at large-scale traffic flows. Problem

a change to the time they set out for work every

routes are scrutinised at network level and traffic

morning? Those are the sort of questions models

behaviour at micro level. “At the DiTTLab we

help us answer.”

concentrate mainly on large road traffic flows, and that includes public transport. I want to develop

60

The data from the models can then be used to

simulation models for all of these levels but that

find out how many people travel between a given

means I need data pertaining to each one.” The

A and B, why they are travelling at a particular

value of the acquired data on large-scale traffic

time, what means of transport they are using, why

flows is largely undisputed but that is not the case

they are choosing a particular route and what the

with the micro level data. “We don’t know very

much about individual behaviour, such as how

Interdisciplinary

people decide to overtake, for instance, or other

The DiTTLab is still finding its feet, says Van

risk taking processes. Our models don’t reflect the

Lint. “We’re in the process of finding data and

way people really behave on the road. In order to

turning them into simulation models. It takes time

remedy that situation we need detailed informa-

to evaluate information properly and establish

tion and incorporate psychological factors.”

links between data. We don’t want to end up to assemble a multidisciplinary team to enable

A recent traffic project is the Urban Mobility Lab

us to create the simulation models we want. Our

which is investigating the impact of such new

scientists are very good at logical thinking but in

infrastructure projects as the North-South Line

order to combine data you also need computer

and the roofing over of the A10 in Amsterdam.

scientists, data experts and other traffic and trans-

Hans van Lint and Professor Serge Hoogendoorn

port knowledge. We are hoping to incorporate

(Transport & Planning) are working with Amster-

psychological research into traffic behaviour as

dam local council to study the consequences of

well. We can only give correct answers to ‘what if’

the changes on Zuidas, the area around Am-

questions’ if we all work together.”

sterdam-Zuid station. Will the traffic flow into the south of Amsterdam increase? Should parking policies be reviewed? “In order to make long and short-term predictions we need to monitor traffic flow and collect data.”

lab stories of science

comparing apples to oranges. We also need time In practice

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lab stories of science

Selfdriving Twizy

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Selfdriving Twizy What could be more pleasant? After arriving at the future Delft-Zuid railway station, you’ll use this electric Twizy to travel to your final destination. After arrival, the Twizy safely, independently finds its way back along the cycle path to the next traveller or its charging station.

Gonçalo Correia from the Transport & Planning department is developing routing strategies and expects to be able to start technical trials in 2016.

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lab stories of science

Selfdriving WePod

67

Selfdriving WePod Work is underway in the garage of the Faculty of Civil Engineering and Geosciences (CEG) on a WEpod. From June 2016 onwards, these self-driving vans will travel between the Ede-Wageningen railway and bus station and Wageningen University & Research Centre. Passengers will be able to book a ride using an app. TU Delft is one of the partners in the WEpod project.

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The six-person vans have a GPS on board

the route the vans will travel and their integration

that was developed by the Department of Geo-

into the transport system.

science & Remote Sensing as well as 3D imaging

Project Coordinator Riender Happee (see photo)

and a radar system developed by 3ME and other

links 3ME and CEG as well as coordinating new

partners. These allow the vans to observe their

projects such as ‘Safe interaction with vulnerable

surroundings and always stop for other road us-

road users’ (Recently granted by STW). On 28

ers. These systems are currently being calibrated

January 2016, Minister Schultz-Verhaegen board-

in CEG’s garage. The Department of Transport &

ed the WEpod during its first official test drive in

Planning at CEG is studying the safety aspects of

Wageningen.

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lab stories of science

Navigating the motorways with pinpoint accuracy

71

Navigating the motorways with pinpoint accuracy Navigation systems which will guide cars and trucks along motorways and through busy city centres with the utmost precision are no longer the stuff of science fiction.

GPS researchers Christiaan Tiberius and Peter de Bakker are testing innovative ways of improving the accuracy and availability of navigation systems. Their research may also bring the introduction of self-driving vehicles one step closer.

There was a time when GPS researchers would

road users are doing.

seek out open spaces where the signal of overflying navigation satellites could be picked up easily,

Tanks in the desert

Tiberius says. But times have changed. ‘These

Most people already have GPS in their cars or on

days we are doing the exact opposite. We specifi-

their phones. ‘The system was originally devel-

cally look for areas with poor GPS reception.’

oped for military purposes in the US to help tanks navigate the desert. Now it is being used for ci-

This explains why fellow researcher Peter de

vilian purposes in urban areas and in vehicles on

Bakker, who, like Tiberius, works at the Geo-

motorways with lots of obstacles. But it was not

science and Remote Sensing department at

really meant for this and there are problems with

TU Delft’s faculty of Civil Engineering and Geo-

it,’ Tiberius says. One of the things that needs

sciences, regularly finds himself driving along the

to be addressed is accuracy, or rather making

same stretch of the A15 motorway near Rotter-

the precise positioning of vehicles cheaper, he

dam. ‘There is a very tall noise barrier there and

explains. ‘GPS really can’t be beaten for precise

if you drive close enough to it, it effectively blocks

positioning. But to achieve this degree of accura-

the GPS signal.’ The car journeys of the two

cy you would need equipment costing thousands

engineers are part of the testing process of new

of euros. It wouldn’t be feasible to build a system

techniques which will eventually help create a

this expensive into every car.’

navigation system with close to a 100% availa-

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bility rate and near-perfect positioning. An added

Bouncing signals

advantage is that it will also be cheap enough for

Another issue is satellite reception, De Bakker

general use. Tiberius and De Bakker think the de-

says. ‘In a busy city centre with a lot of high build-

velopment of the system may also accelerate the

ings two effects can come into play. The buildings

introduction of self-driving vehicles where drivers

can block the signal and in tunnels there is no

no longer have to worry about what their fellow

coverage at all. An incoming signal can also be

distorted when signals bounce off the façades of

availability even more. This is enabling exact

buildings.’

positioning, possibly even in built-up city centres.

‘That can lead to a positioning deviation of hun-

We are now in the process of testing this method

dreds of meters,’ Tiberius adds. ‘And that could

with our colleagues of the Transport and Planning

literally be fatal if you are in a self-driving car.’ In

department in places where multiple obstacles

order to improve the accuracy of the GPS signal

restrict GPS reception, such as motorways.’

without the need for expensive equipment Tiberius and De Bakker have been testing various tech-

SuperGPS

niques. ‘By using a smart algorithm for positioning

But even if the method delivers on its promise,

we can improve accuracy. That will also work with

complete GPS coverage will remain elusive.

smaller receivers which would only have to cost

‘Even with extremely precise navigation tech-

20 or 30 euros,’ Tiberius says. ‘The algorithm

niques a solution will have to be found for tunnels

will compensate for a number of error sources,

or covered roads where reception is impossible,’

such as signal delays which occurs as the signal

Tiberius says. To find this missing piece of the

travels through the atmosphere. We have already

puzzle a new research project dubbed SuperGPS

tested this technique by having students travel a

has been set up jointly with VU University,

fixed stretch of the A13 motorway and comparing

research institute TNO and financed by Tech-

their navigation data with those of the expensive

nology Foundation NWO-TTW. The project will

reference system. This resulted in a deviation of

concentrate on the development of a very precise

about half a metre. This technique could soon

navigation system which will not be dependent on

be ready to be applied, for instance in assisted

satellites.

driving where cars take over certain tasks from the driver.’

‘What we are going to do is place navigation

Combining satellites

connection with an atomic clock and which send

It won’t, however, be accurate enough for

out a radio signal. So essentially the boxes are

self-driving cars. But there is another technique,

working GPS satellites except they are located

developed some fifteen years ago, which may

on the ground,’ Tiberius explains. ‘There is a lot

hold the key to a solution. Tiberius: ‘It’s a method

that we still have to find out but the plan is to test

which made it possible in principle to achieve

SuperGPS in cars in four to five years.

near-perfect positioning with a cheap GPS receiv-

So when will the first self-driving car hit the Dutch

er. But it wouldn’t work in practice because the

motorways? Tiberius and De Bakker are not

GPS network was too sparse at the time and not

volunteering any predictions. ‘We are not the

enough satellite signals were available. But the

only people making it happen. The introduction

development of satellite navigation systems has

of self-driving cars depends on many factors. We

been taking great strides in the last few years.

specialise in GPS and navigation systems and it

There’s the Galileo programme in Europe, for

so happens this ties in with the current interest in

instance, and the system the Chinese are building

the design of self-driving vehicles. It’s nice to see

at the moment.’ The result is that many more

the two coincide.’

satellites are circling the earth. ‘These satellites can be used and combined, which increases

lab stories of science

boxes alongside the motorway which are in direct

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