Low carbon bus trial

Basic Information

Mobility solution ID






An innovative hybrid diesel-electric bus was trialled in Bath by bus operator First. The vehicle operated on the Bath’s Park & Ride routes for 18 months, and was able to operate in the historic City Centre on electric power alone, with zero emissions.

Implementing sustainable mobility

The aim of the measure was to demonstrate the feasibility of hybrid diesel-electric double deck bus operation in the City of Bath.

Before this trial all public transport vehicles in the area were diesel powered. Diesel-electric hybrid technology is innovative within the UK and the trial vehicle demonstrates unique technology, enabling it to operate further on electric power than most other hybrid buses in the UK.

The city sought to identify a vehicle with reliability and cost of operation comparable to that of a conventional diesel bus, but with improved emission standards (including carbon) and reduced noise levels and fuel use.


A hybrid diesel-electric double deck bus, which operated with a small 1.9 litre diesel engine, was identified for the 18-month demonstration project. Work was carried out on the vehicle to make it suitable for operation in Bath and drivers and mechanics were trained to operate and maintain the vehicle. The trial commenced on 31st August 2010 and ran until 29th February 2012.

During the trial the hybrid bus was compared with conventional diesel buses operating on the same routes to test emissions, noise levels, reliability, running costs and fuel use.  


• Nitrous Oxides reduced by 37% (Target 90%) • Carbon Monoxide reduced by 93% (Target 80%) • Carbon Dioxide reduced by 38% (Target 40%) • Fuel consumption reduced by 28% (Target 40%) • 8% of respondents on the hybrid bus thought it was noisy or very noisy, compared to 15% on the conventional diesel bus, a 47% reduction (Target 30%) • Availability for service was relatively poor at 74% compared with diesel 95%. • Operating Costs reduced by 4p/km


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