Train-mounted microwave system aims to end leaf-induced rail misery

As we welcome autumn with pumpkin-flavored beverages and
stylish attire, train operators see the season as a cause of disruption. This
is all thanks to leaves fluttering down onto the railways and turning into a
wet mulch as trains speed over them. The slippery coating requires train
drivers to brake earlier when approaching stations and signals, and then
accelerate cautiously to avoid wheel-spin. 


Because the situation is so common, annual timetable
adjustments are made, and the London-based Imagination Factory hopes to
alleviate the issue with bursts of microwave energy to dry out sections of the
tracks. In 2014 the company was awarded funding by the Rail Safety and Standards
Board (RSSB) to take forward its solution as part of the “Predictable and
Optimized Braking Challenge.”

The company’s solution, which has completed an early proof
of concept feasibility study, would see microwave energy directed at railway
tracks during braking. According to engineering lead and co-founder of
Imagination Factory, Julian Swan, the idea is to dry the contact patch
between the rail and wheel interface, which is 12 mm wide.

We are not intending to dry the full track
width,” he told The Engineer. “Our design
vision is to have a modular approach to enable us to treat the tracks
individually and progressively down the length of the train.”

When it comes to the microwave element, Swan said the
initial Proof of Concept rig operated at 6 kW using an 896 MHz source, but that
in the next phase of development, the company will look into 2.3 GHz as this
can improve energy density and component compactness. It’s also proposing
separating the power electronics from the microwave generation by the use of
coax cabling.

“This will enable us to
locate some of the larger more sensitive pieces of equipment on
the sprung chassis of the carriage and the more robust solid state
elements of the microwave antenna can be located near the wheel,” said Swan.
“This flexible modular build principle should enable the final design
to be retrofitted as well as incorporated in new build.”

As of now, scale tests have been completed at 1 MPH, but the
company’s mathematical model suggests a linear relationship enabling full
effect at up to 50 MPH. The company plans to demonstrate this during the next
phase of funded development through the RSSB. Additionally, the energy used for
the system during braking could also be created by regenerative braking. Since
regen brakes aren’t able to return the energy to the grid due to the quality of
what’s created, the new system could easily utilize that energy.

According to the company, if all goes to plan, the system
could be introduced within two years. Currently it’s in discussion with rail
operators and train building companies including Bombardier and Hitachi, which
could fit the system on new carriages.