Ricardo presents Brighton bus emissions data

Consultancy completes project to assess level of emissions from buses on routes within city

Disruptive traffic flow around key areas of heavy vehicle use correlate closely to locations of poor air quality, research carried out by environmental consultancy Ricardo AEA in Brighton has shown.

A Brighton & Hove bus, a regular sight in Brighton city centre, passes the Royal Pavilion

The research, which was carried out on behalf of Brighton & Hove city council and The Brighton & Hove Bus and Coach Company will be used by the authority to inform proposals for improving traffic flow within the city.

Among the main contributors to the output of emissions was the ‘erratic’, stop-start operation of buses operating on along an uphill stretch of a bus route monitored as part of the study.

Ricardo claimed that the demanding cycles of acceleration and braking would be expected to challenge the performance of vehicles and strongly correlated with real time vehicle emissions data which demonstrated higher levels of pollutants at these locations.

The tests were carried out on buses fitted with exhaust gas recirculation (EGR) aftertreatment technology, selective catalytic reduction (SCR) aftertreatment, and a further SCR-equipped diesel-electric hybrid vehicle.

Monitoring

Each bus was instrumented with HORIBA’s advanced Portable Emissions Monitoring System (PEMS) equipment and artificially loaded with ballast representing a 70% passenger load (for reasons of health and safety, passengers were not carried and the test runs were not part of the regular timetable).

The vehicles were tested on multiple trips and in normal traffic during business hours, stopping at regular bus stops in a similar manner to the normal passenger service. A number of different drivers and driving styles were used in testing one of the three vehicles so that the effects of these variables could also be assessed.

Commenting on the results, Jon Andersson, Ricardo’s manager of aftertreatment and chemical analyses, said: “The results of this work have provided some potentially very valuable insights into vehicle emissions at a location of known poor air quality. I hope that the information generated is of use to the city council in its planning of future traffic improvement schemes.

“The recent availability of PEMS equipment allows us to take real-time measurements of operating vehicles following their normal duty cycle. This approach, as demonstrated in this project, allows us to understand at a detailed level exactly where and how emissions are being created.”

The results of the research were presented to Brighton & Hove City Council in early July.

Ian Davey, Brighton & Hove city council deputy leader and lead member on transport, said: “Brighton & Hove, like many cities, suffers sever air quality problems in our densely populated and intensely used urban centres. We know that the main contributor is vehicle emissions yet there is no easy solution.

“It is vital that any action taken to address the problem is based on evidence and we are grateful for the work that Ricardo is doing with Brighton & Hove buses to help us all better understand the cause of the problems and to help focus our efforts on the most effective solutions.”