Rail Industry Focus


Japanese knotweed an ‘unknown’ quantity for rail

Source: RTM Feb/Mar 16

Will Sillar, founder and managing director of National Knotweed Survey, talks to RTM about the impact Japanese knotweed could have on rail assets in the UK.

Japanese knotweed is a highly invasive, non-native plant found in the UK, which is estimated to cost the British economy at least £166m per year, according to figures used by Defra. 

The total cost of invasive non-native species is estimated at £1.7bn per year in the UK, which is mainly borne by the agriculture and horticulture sector. However, many other sectors, including transport, construction, aquaculture, recreation and utilities, are also affected. 

In 2012, a London Assembly Environmental Committee report stated there is a need for Network Rail to control invasive and foreign species such as Japanese knotweed, which can “negatively affect both railway land and neighbouring sites”. 

RTM spoke to Will Sillar, founder and managing director of National Knotweed Survey, who said the true extent of Japanese knotweed’s presence across the country is “unknown”.  

In response to increasing reports of property transactions being lost as a result of the presence of the aggressive weed, which can grow through concrete and damage houses, Sillar decided to launch National Knotweed Survey to help get the problem under control. 

Good vector for growth 

“Historically, we think that if 1% of all properties sold in a year need to be worried about knotweed, either because it is adjacent to the property or on the property itself, we think the implications for utilities and assets are north of that – more than a 1% problem,” he said. 

“Our reasoning for thinking that is because it is well known and established in the literature that railways, roadways, canals and watercourses, of different kinds, are good vectors for knotweed. This is because it travels by mechanical means and not by setting seed. 

“If you come across some it has either been dropped there or moved there deliberately.” 

Sillar added that National Knotweed Survey, which  brings together decades of academic research, historical records and high-tech aerial imaging to form a resource for interested parties, has been years in the making. 

“We have brought together a team of experts to create the UK’s definitive central resource on knotweed, with two main objectives: to define a universally recognised surveying report template, and more ambitiously, to create a comprehensive database of where the plant is or might be, which can be included as part of every homebuyer’s searches and surveys,” he said. 

The invasive plant is yet another source of potential degradation in ageing railway assets. “When stuff crumbles and needs maintenance on the line, or in the built asset, that is one problem,” said Sillars. “But there is another issue with knotweed: if it goes over the fence into a neighbouring property, you are vicariously liable.” 

In October 2014, the government brought in legislation to allow councils and police to order someone to control or prevent the growth of Japanese knotweed through a community protection notice. The legislation made the breaching of the notice a criminal offence, which could lead to a £2,500 individual fine rising to £20,000 for organisations. 

“It is one of those things where the legislative framework has tightened twice in the last decade about knotweed. If you dig knotweed up – and it is the only effective way to get rid of it – it has to either be buried in a contained site or incinerated,” he said. 

“Questions of how to spot it, what to do, and whose responsibility it is, have led to hundreds of millions of pounds’ worth of business falling through every year.” 

He added that, historically, there has been a tendency to play down the importance of knotweed, but now it is a subject that organisations can’t afford to ignore.

Tell us what you think – have your say below or email opinion@railtechnologymagazine.com


Stephen Blunt   23/03/2016 at 18:44

Japanese knotweed certainly is a major problem for development and for householders. There is a third way to eradicate it quickly, without taking huge quantities of soil to landfill. The Klaro on-site eradication system is environmentally friendly and far cheaper than landfilling, and doesn't leave a waste burial cell to restrict future development. But the key is to take action now, and not leave a small problem to grow - literally - into a large one.

John Hughes   08/04/2016 at 16:05

Cockett Bank Swansea must surely be the national rail knotweed centre.

Mark Tierney   12/10/2016 at 11:49

I've just had another house sale fall through because of Japanese Knotweed encroaching from Network Rail land. They say they are treating it but won't provide any official documentation ie Management Plan/Guarantee of Eradication. How is this acceptable? I wouldn't mind but the infestation is approx 80 metres away from my property and poses no risk, however because it is leasehold it is flagged up on the LPE1 form.

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