Month: September 2012

NGT – the energy efficiency myth – part 1

The scientific method that represents power production efficiency in power stations and vehicle energy efficiency are called Sankey diagrams. I have attached one below. They are good at illustrating the problem with power stations.

 

Power production efficiency in power stations and vehicle energy efficiency, in any type of vehicle, are totally different matters. It’s wrong to confuse the two.

After the electricity is made in a power station, losing 70% to heat losses, it loses more in transmission to the city and more in transforming the current to the NGT system. After that the electric cable and the vehicle lose even more. The total efficiency is hard to calculate on the NGT, but it will be in the region of 10%.

Diesel engines with intercoolers, turbo chargers with digitally-controlled fuel injection produce very high efficiency-up to 50% is not uncommon. They are used on the new First Bus double-deckers.

Electrical vehicles have an advantage over diesel because they accelerate and decelerate faster. Also they produce no local pollution.

Both types of motors suffer on urban travel because they constantly stop and start.

The diesel still has a big very big edge in overall fuel efficiency over power station produced electricity vehicles such as the NGT.

NGT – What happens to the Trees on the A660 green corridor?

There is no official information on the height of the catenary system, that supports the cables of the NGT trolley bus scheme. Unlike continental trolley buses, the system has to be of an unusual height because double-decker buses will travel under it for many sections of the route. The mast height of 6.5metres (about 20 feet) is my “guestimate” as safe clearance for a 4.3 metre bus is required. The power line will carry about 700 volts.

The design and build must allow for all conditions. Engineers will have in mind extreme conditions such as a winter gale.

The design of the route will acknowledge that no tree or branch can lean over this catenary system. There can be no circumstances where a branch can be allowed to touch the masts, cables or braces. Re-growth of a brashed (cut back) tree will not be permitted. The best method of ensuring safety and line continuity is to remove the tree because continuous maintenance will be difficult. An extensive tree removal programme will threaten our green corridor, from Monument Moor to beyond the Lawnswood roundabout. When you next travel along the route look up and estimate the lean of the branches over the A660 to get an idea of which trees will be removed. It looks like a very large number.

The gantry system on a catenary system – Environmental and Aesthetic impact

There are many examples on the web of what a trolley bus support system looks like. The drawings on the NGT website indicate little and give no measurements. The diagram above shows what it could, and probably will, be like. There is no hard information from the proposers of the NGT. The dimensions here are calculated on the height to accommodate a double-decker bus. The cute diagrams of traffic-free streets and gossamer cabling systems on the NGT website bear no relationship to the engineering and safety requirements and their visual impact.

The probable height of the catenary system to accommodate double-decker buses on the route of the NGT

There are very few single deck trolley bus systems

There are very few single deck trolley bus systems that share the route with double-decker buses. Single-decked trolley bus routes tend to be designed for special routes not shared with high-sided vehicles. The NGT shares many parts of its route with double-decker buses. The diagram above shows the problem. It creates a very high catenary system. Double-decker buses raise the roof on the engineering. The heights above are researched but are estimates only. The power cables in the catenary system will carry up to 700 volts. So there won’t be any open-topped buses in the unlikely event of Leeds United winning a trophy anywhere near the NGT system.

It is very hard to get detailed information on the NGT Leeds scheme. There is none given on the NGT website except unrealistic pictures which are just a marketing exercise. The information I have given is based on other schemes, all of which use slightly different constructions of their catenary system.

Calls for an underground

Photo courtesy of Adam E Moreira

The Yorkshire Evening Post has recently published several letters calling for Leeds to have an underground system.

To those who think an underground system would be too expensive, Janet Bailey points out that tunneling is cheaper now than it used to be. Hannah Johnson points out that other European cities are building underground systems whilst Leeds gets left behind. D Birch says that private companies should be invited to provide us with an underground system. Terry Allinson says there should be an underground link between Leeds and Bradford. And George Horsman informs us that back in the 1930s, Leeds City Council had detailed plans for building an underground system.

Leeds residents condemn NGT

The Yorkshire Evening Post has published several letters recently that criticise the NGT trolleybus scheme.

There were letters from Bill McKinnon and Dawn Carey Jones who are concerned about the plan to route the trolleybuses across a section of Woodhouse Moor. Andrew Batty points out that the trolleybuses will be bendybuses with wires, and that bendybuses have been scrapped elsewhere because they are cumbersome and unpopular. Peter Brash makes it clear that trolleybuses will just add to congestion. Kim Cowell relates how Transport for London ruled out the use of trolleybuses in London on the grounds of inefficiency and cost. Sarah Sullivan reveals that the Department of Transport estimate that the NGT trolleybus scheme will cost Leeds businesses in excess of £200 million.

NGT and Metro’s obsession with trolleybuses

An earlier incarnation of NGT was the failed Electrobus scheme of the 1980s. Metro’s original intention in 1980 had been to re-introduce trolleybuses to Bradford. But after two failed attempts to secure government funding, Leeds was included in the scheme, in the hope that this would persuade the government to change its mind.

But the government refused funding again on the ground that the trolleybus would only be economic if it had no competition.

Metro decided to go ahead anyway. But then in 1990, when an independent bus company announced plans to set up a rival bus service along the proposed first trolleybus route in Bradford, Metro withdrew its plan. It had taken them 10 wasted years to finally accept that trolleybuses couldn’t compete economically with diesel buses, the very same reason that trolleybuses were originally withdrawn from service.