Background
The purpose of this case study is to compare the behaviour of the MMRCV with an RCV in municipal (domestic) waste collection and transportation activity. Trials were conducted with the London Borough of Bexley and its waste contractor Kier Group.
To try and achieve a like-for-like comparison the same driver and team were employed throughout the trial. The team - Team 2 - was selected from Bexley’s 14 teams at random and the normal waste collection and transportation activities of this team, working with the RCV, were monitored and recorded over a period of 1 week.
The team’s RCV was then
substituted with the MMRCV for the following week’s work with the collections over the previous week replicated, as far as was possible. As previously, activities with the MMRCV were monitored and recorded.
The trial was also designed to explore how the MMRCV performed in different waste stream collection activities to provide a useful comparison with the RCV, which does not usually perform well in collections across all waste streams.
It was not the intention of the trials, or this case study, to provide a conclusive outcome but rather to better understand the characteristics of the MMRCV against an RCV and identify the differences, opportunities or challenges to assist in the future development of
implementing an MMRCV-based waste collection system.
Characteristics of Bexley’s waste collection and transportation activity
The London Borough of Bexley covers an area of 11.2 miles by 7.0 miles and has 1,701 streets.
There is a wide contrast between different areas within the borough. The property types range from high-rise flats to houses worth over £1m, and from high density living
accommodation to semi-rural dwellings. Street types also vary between narrow streets with parked cars on both sides to housing areas with garage and driveway parking with little on-street parking.
The London Borough of Bexley is a unitary authority and currently disposes of its
ordinary domestic waste at SELCHP (South East London Combined Heat and Power) in Lewisham or to landfill at Rainham in Essex.
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Bexley is the top London borough achieving 40% household recycling and composting levels in 2006/712. There are three rounds collecting garden and kitchen waste for composting (green waste), paper and cardboard, and glass and plastics in addition to a residual waste collection round.
The refuse collection fleet is made up of:
- 14 x 26 tonnes, 4.5m wheelbase, Dennis Phoenix RCVs that are between 3 and 4 years old.
- 1 x 17 tonnes, 3m wheelbase, Dennis Phoenix RCV, 3.5 years old.
- 2 x 26 tonnes, 4.5m wheelbase, spare vehicles, over 10 years old.
- 8 x 26 tonnes, 4.5m wheelbase, Faun Rotopress RCVs (used on compost collections).
- 4 x 26 tonnes, 4.5m wheelbase, Faun Rotopress RCVs (used on paper and cardboard collections).
- 4 x specialist glass and plastic collection vehicles.
Some of the current and future challenges in the borough regarding waste collection and disposal are:
The very high levels of unpredictability in the time taken to transport the waste to either SELCHP or Rainham because of extreme road congestion conditions. SELCHP
requires a journey on the A2 towards London whilst access to Rainham landfill is via the M25 Dartford Crossing. Both routes regularly suffer from traffic incidents and extreme congestion.
The changing levels of the different waste streams as the volume of recycling activity increases.
The future locations to which waste will be transported
(including the impact that the new waste incineration plant at
Belvedere will have on Bexley’s operations).
Changes in legislation, penalties and tax on CO2 emissions, road congestion, landfill, fuel and recycling.
A desire to change the current fleet’s replacement cycle from 7 years to 5 years.
The borough is adjacent to the River Thames and there may be opportunities, in the future, to use the river for transporting waste.
The borough’s municipal depot, at Thames Road, is in the far extreme north east corner of the borough and, therefore, vehicles incur significant mileage in the course of normal operations. A depot in the centre of the borough would prove helpful in this respect. The waste collection activity is currently contracted out to the Kier Group.
12 Source: Capital waste facts: www.capitalwastefacts.com Thames Road Depot
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The trial: summary of data collection
Table 12: Waste collection times and payload comparison – RCV and MMRCV
RCV MMRCV
Wednesday 242min 17,320 216min 12,680(2)
Thursday 233min 17,500 179min 16,270
Friday 219min 15,760 193min 14,690
Total 1,187min 80,585 1,034min 72,920
(1) This is a normal payload for Monday collections (+/- 10% variance is not unusual) as it is usually a light day.
(2) The gofer vehicle (see below) was used extensively during the round which reduced the payload collected by the MMRCV.
What the data shows:
The average daily payload collected by the RCV was 16,117kg (16.117 tonnes) and 14,584kg (14.584 tonnes) for the MMRCV. These figures are much closer if Wednesday’s figures are excluded: RCV - 15.8 tonnes, MMRCV - 15.1 tonnes.
It took an average of 14.7 minutes to collect 1 tonne of waste with the RCV and half a minute less at 14.2 minutes to collect 1 tonne of waste with the MMRCV. Over the course of a day the MMRCV would take 8 minutes less than the RCV to collect the same amount of waste.
Other tests have been performed on the MMRCV to measure the waste collection efficiency.
These tests include the cycle time to move the waste into the container (see Technical Comparison on page 25) and samples of the time taken to collect waste over a given stretch of road. In all these tests the MMRCV has been shown to be quicker than an RCV.
Mitigating factors
The aim of the Bexley trial was to achieve a like-for-like comparison between the RCV and the MMRCV as far as this is possible. The problem that occurs in attempting to compare similar waste collection operations is that it is very much a case of ‘no two days are the same’. Waste collection efficiency can be affected by factors that include: different weather conditions, obstructions in the road, different crew, differing volumes of waste in each bin and where the bins are located. The variations that were observed in the Bexley trial included:
Crew
The trial commenced with 5 crew (4 loaders, plus driver) working the vehicle. Both during the week and, occasionally, during rounds, individual crew members are taken off to supplement other crews/rounds. In addition, there is wide use of agency personnel to cover labour shortages. This can adversely affect collection efficiency by slowing down the loading rate.
Gofer Vehicle
Another complication within the Bexley operation is that they frequently deploy what they refer to as a Gofer (spare vehicle and driver). This is used to assist with the waste
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collection, filling in when the RCV is full and is being driven to the tip location between each two loads collected. The Gofer vehicle ensures the crew can keep on working and the round is continuous.
As the MMRCV has a lower payload capacity, increased mobility and had a faster bin loading cycle speed than the RCV, it became full sooner on the round than the RCV.
Further, because a mobile crane was used to swap the containers it was taking longer to return to the round for the second load collections. This meant the Gofer vehicle
substituted earlier in the MMRCV round and was collecting for longer than on the RCV round, making like-for-like comparisons very difficult.
The anomalies between the two operations restrict the ability to use the data collected in its raw form. The data can only be used in conjunction with understanding what actually took place on the days in question.
There were two periods during the two-week waste collection operations that were very similar for both the RCV and the MMRCV. These periods were the first 13 streets on the Tuesday and the first 10 streets on the Thursday. During these periods the data on the time comparison is:
Table 13: Comparison of times achieved by MMRCV and RCV vehicles along specific collection routes in Bexley.
Collection Route
From To Time taken
(minutes)
MMRCV A210 Blackfen Road Foxglove Close 94
RCV A210 Blackfen Road Foxglove Close 126
MMRCV Maiden Lane Iron Mill Lane 132
RCV Maiden Lane Iron Mill Lane 158
Over these sections the MMRCV took a combined 226 minutes against the RCV which took 284 minutes to perform the same waste collection activity. In this measurement the MMRCV performed 20% faster than the RCV.
The differences between the MMRCV and the RCV are not specific to the MMRCV’s unique design and these features could also be incorporated into an RCV. For example, the MMRCV uses a Mercedes chassis with rear steering axle and a 3.45 metre wheelbase, making it very manoeuvrable (and faster) in narrow streets. The RCV, on a Dennis chassis with fixed rear axle and 4.5 metre wheelbase, handles different street layouts less well. A different chassis could improve manoeuvrability and speed.
From all the testing carried out, not just in the Bexley case study but also in other operations, it can be concluded that the only area in which the MMRCV does not perform with at least the same level of efficiency as an RCV is in the amount of waste (payload) that can be collected before the container is full.
The payload data above shows the average daily payload of the RCV is 16.1 tonnes. In activity where the MMRCV container has been filled the average payload being achieved is
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8.3 tonnes. Therefore 16.6 tonnes can be collected in one day with two full loads, which is above the RCV’s daily average.
What might at first appear to be a reduction in the waste collection efficiency with the MMRCV would not be the case if the daily rounds were changed to better suit the MMRCV operation. Further, the MMRCV is 1 metre shorter in both wheelbase and overall length therefore the 5 metre length container can be increased in size to a 6 metre container which is likely to increase the collection capacity to between 9 and 10 tonnes per load. This could only be confirmed through additional road trials with a 6 metre container.
Transportation of waste
The team normally transports the collected waste to SELCHP on a Monday, Tuesday and Wednesday and to landfill at Rainham on a Thursday and Friday.
The trials showed that in a week without any incidents on the roads the RCV transportation activity was 11 hours and 46 minutes, covering a distance of 243.7 miles. However, it is not usual to get a full week’s waste transportation activity without any delays so this estimate reflects unusually good operational conditions for these activities.
The trial involving the MMRCV was very different as it encountered difficulties through road congestion and closures, waste facility closures, and waste facility suitability for MMRCV-based operations.
Hook loader drawbar vehicle with two containers
It was not possible to replicate what would actually happen in an MMRCV operation.
Nevertheless, data collected from the trials to model what the activity could look like in comparison to the use of the RCV is shown in Table 14.
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Table 14: Model prediction for use of MMRCV on existing RCV routes in Bexley.
RCV Actual MMRCV Model
Day Time (minutes) Distance (miles) Time (minutes) Distance (miles)
Monday 123 39.4 121 32.5
Tuesday 174 47.1 131 36.0
Wednesday 151 41.8 137 38.5
Thursday 129 52.6 131 33.3
Friday 129 62.8 147 37.8
Total 706 243.7 667 178.1
Model based on: two depot locations (Thames Road and Hurst Road) with 10-minute container swap.
Data drawn from actual trials, Green Flag Route Finder and Tom-Tom.
This model shows a reduction in time of 39 minutes per week and a reduction in distance travelled of 65.6 miles, due to reconfiguration of the RCV rounds to suit MMRCV operations which would equate to a reduction in mileage across the borough of 47,756 miles. Data from the wider waste study discussed in Appendix C modelling the London Borough of Redbridge shows a minimum saving of 50,000 miles for an 8 tonne MMRCV payload with one transfer point rising to about 79,000 miles for loads over 10 tonnes with 2 transfer points. This is shown in Graph1 below and would represent a saving of between £20,000 and £32,000 in fuel costs or a reduction of about 40 to over 60 tonnes of CO2.
Graph 1: Modelling of Application of MMRCV in LB of Redbridge and Dagenham
-100000 -50000 0 50000 100000
8t capacity 9t capacity 10t capacity 10.5t capacity
Capacity of MMRCV
Distance travelled saved/ mile
2 transfer pts 1 transfer pt 1 transfer pt 0 transfer pts
One of the potentially greatest benefits of the adoption of the MMRCV to the London Borough of Bexley is that it makes possible management of the collection round such that any time and cost uncertainty that currently occurs on a frequent basis through road congestion is minimised. These benefits can only be quantified through further detailed trials.
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Queen Elizabeth 2 Bridge with traffic at a standstill
Because the containers would be swapped on the MMRCV no further than 4 miles away from the collection activity it means that the driver and crew are not negatively impacted.
Containers can be stored13 until road conditions are favourable for efficient transport to disposal/treatment.
Collection of different waste streams
The London Borough of Bexley currently operates 4 different types of vehicle to perform 4 different types of waste collection:
14 RCVs to collect ordinary domestic waste.
8 Rotopress refuse collection vehicles to collect garden and kitchen waste (composting/green waste).
4 Rotopress refuse collection vehicles to collect paper and cardboard (this is the same type of vehicle as above but it is not easily possible to perform a dual function with these vehicles due to the cross contamination of waste).
4 dual-bodied, top-loading refuse collection vehicles to collect glass and plastics.
Because of the different compaction method employed the MMRCV can collect ordinary waste, garden and kitchen waste, paper and cardboard, and plastics. It has not yet been tested on glass, but it is expected that top loader vehicle currently being used will continue to perform better in glass collection.
As the MMRCV operation is based on a swap body basis then it is perfectly feasible to use the same vehicle to collect at least 3 of the 4 different waste streams in Bexley. Though it is expected that each waste stream would be collected in specific containers that require minimum maintenance (e.g. cleaning) or preparation prior to reuse (e.g. marked or colour coded containers used for the collection of green wastes only). This would require evaluation of management and costs in full field trials where the MMRCV vehicle would replace an existing fleet of RCVs.
Thus, the collection of the different waste streams with the same vehicle would further reduce costs14, road miles and CO2 emissions. It is estimated that the potential saving on
13 Some analysis of container numbers required is discussed in the Bisham (2006) report: Outline Specification for bespoke loading and unloading facility suitable for London’s narrow canals – Lea Navigation Pilot.
14 See projected capital cost savings for Aberdeenshire’s adoption of MMRCV technology on page 11.
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capital costs for the Bexley fleet in adopting MMRCV vehicles to replace its RCV fleet is about £1m over a 5-year period15.
It is difficult to assess the mileage and CO2 reductions until the probable end destination for the containers is known though, undoubtedly, significant savings are possible. It is
acknowledged that the end destinations for waste treatment/disposal may change, particularly given the road congestion issues and diminishing landfill space. Additionally, planning permission has been granted for a new EfW (Energy for Waste) plant at Norman Road, Belvedere in the borough. This will provide a more accessible and closer location to the actual collection rounds but it won’t be operational for at least another 10 years.
Optimising MMRCV benefits within Bexley
To make the best use of the MMRCV reorganisation of rounds would be necessary together with development of another depot closer to the centre of the borough, rather than working solely with the existing facility at Thames Road (in the far north east of the borough). A crucial factor to be addressed for the adoption of the MMRCV would be the provision of container swapping and storage in locations close to collection rounds.
15 Estimated from data collected from the Bexley trials.