Trolley bad show

In reply to the comments by Max Lazarus on the merits of the trolley bus (

, 12 February) I used them when at school and I understand they were phased out for a number of reasons.

To start with, one bus could not pass another that was stationary. And at 'Y' junctions and crossroads where two or more bus routes met, conductors had to change the points in overhead power wires.

Also, 'off wire' movement was limited. Although the vehicle had reserve battery power, this provided only very limited speed and range, and was used in emergencies or within maintenance depots.

Because of the overhead cables, the bus itself required a lot of headroom under bridges as well as restricting the space for other vehicles. Another problem was cost. Overhead power systems were expensive to run and could also be dangerous in wet or misty weather.

But the main factors that led to their demise was that they could only operate where the power cables ran and they caused delays at 'Y' junctions and crossroads. As more private cars appeared and more junctions fitted with traffic lights, the trolley bus was gradually replaced by the more flexible diesel bus.

Having said that I feel there is still a place for the trolley, such as on one-way systems in cities.

And with a greater priority on clean public transport, a second-generation trolley bus — a tram on road wheels, in fact — could be introduced. Probably a single-deck bendy bus with dual electric/gas power plant to give maximum flexibility with minimum pollution.

Interestingly London transport's trolley bus was fitted with a 'regenerative braking' system which stored energy in a large flywheel. With modern high-strength/ low weight materials this technology could be introduced into many forms of current bus/tram/ trolley. So the challenge for engineers is not to put the clock back to the mid 20th century, but to look forward to solutions for now.