Solid MetroDecker performance

Optare’s new decker on the Millbrook track

It was in May that Optare took the wraps off the MetroDecker, the double decker it had been promising for over a decade, in a static launch at London’s Transport Museum. Framed in stainless steel and weighing in at under ten tonnes it immediately aroused attention but until this week there had been no opportunity to evaluate whether a bus that looks good both on paper and in pictures can do the business on the road. Was the 5.1-litre Mercedes-Benz OM934 engine up to the task of propelling a double decker, had Optare’s success in reducing weight been at the expense of on the road stability and could a bus designed and built in eight months actually be any good?

There I was traipsing round the myriad stands of the IAA in Hanover when the invitation to go to Millbrook a week hence came through. It was short notice and I had other things planned but it was too good an opportunity to miss. Messages shot through the ether to our regular test driving team and while Simon Dew was tied up, Andrew Fowler could make it, so at 14.00 last Wednesday we turned up at the gatehouse of the newly independent Millbrook facility, eager to get our hands on the MetroDecker.

Throughout the driving experience, we found stability in all conditions was the watchword of the MetroDecker’s performance

Throughout the driving experience, we found stability in all conditions was the watchword of the MetroDecker’s performance

Climbing and descending the 11.6 gradient of the hill routes was effortless

Climbing and descending the 11.6 gradient of the hill routes was effortless

A short trip in a rather shabby Vauxhall Vivaro took us to one of the site’s corporate hospitality areas where a vision in metallic blue sat resplendent in the afternoon sunshine while Tim Hampshire, Optare’s Group Product Reliability Manager, added the final lustre to it with his polishing cloth. Clearly they wanted to make an impression but first there was a cup of tea and, having already filled in the form to promise that we wouldn’t take pictures of anything other than Optare MetroDeckers, another form giving over all our worldly possessions and further requiring that we wear our seatbelts – the third such form I’d signed in a month.

The sky looked as if it might have damper plans for October than September so I was keen to get a set of images while it still looked its best, a needless concern as it turned out. Photography had been challenging at the Covent Garden launch, to say the least, and now that I could actually see the offside of the bus the impression was that it was perhaps more stylish than I had first thought. Then I’d thought it odd to launch a bus to a London specification, in London and paint it blue rather than red, but here, well it looked very presentable in the best traditions of Optare demonstrators, and there have been a good few of them over the years.

Tim ran through the various sections of the Millbrook site on which we were to be permitted to take the bus and they were pretty much the ones I would have chosen, fortunately excluding the Belgian Pave as I’d already had a clean bill of health from the dentist that week and I was quite anxious to keep my molars in similar condition. Spookily, Optare’s new Marketing, Press & Events Manager, Rebecca Green, used to have her teeth inspected by the self same chap, but I digress.

Before we set off I should perhaps remind you about the background and specification of the MetroDecker, assuming you don’t have the original report from issue 1278 on 30 May 2014 to hand. Right back when Optare was acquired by NABI, so long ago that I can’t remember when, one of the important products they were working on was a new double decker. A lot of water went under the bridge, Optare’s long serving Spectra was discontinued, and amidst more changes of ownership East Lancs joined the fold before Optare became part of Ashok Leyland, then with the closure of the Blackburn facility, the group found itself without a double deck product. There had been false dawns, the Raptor, about which the less said the better, and a prototype new decker known internally as IDD (Integrated Double Deck) which looked suspiciously like an Olympus, added to the decades of East Lancs’ experience and from all this only the front and rear axles, the near ubiquitous ZF AV132 portal unit at the rear and the RL75EC independent at the front, also used in the IDD, was carried over. The rest was completely new.

To be fair, there was a pointer to the way things were going in the IDD which had the six-cylinder Mercedes-Benz OM906 unit at the rear. The MetroDecker also has a Mercedes-Benz unit, albeit a four-cylinder, but this is the OM934LA, a 5.1-litre from a completely new generation of Mercedes-Benz engines developed for Euro6 and equipped with a dual stage variable geometry turbo. It produces 228bhp (170kW) at 2,200rpm and peak torque of 900Nm at 1,200rpm. When first mooted, this would have made Optare the only manufacturer offering a double decker with a Mercedes-Benz power unit, but in the meantime, Wrightbus has moved to the three pointed star for its own integral products and is fitting the same engine.

Not many years ago 5.1-litres would have sounded a bit weedy for a heavy duty single decker, let alone a double decker, but the world’s gone to hell in a handcart and now small is beautiful. The ADL Enviro400, successor to the Dennis Trident which started the downsizing trend by switching from the Cummins C-Series to the B-Series (six-cylinder), now has the biggest engine among the competing low floor double deck designs, Volvo having also switched from nine litres to the 5.2-litres of the D5K unit originally used in its hybrids. You know the arguments; smaller engines are more efficient, use less fuel, weigh less giving you more passenger capacity and give you the same power output.

The transmission is the ZF 6AP 1000B six-speed fully automatic with integral hydrodynamic retarder and angle drive output. This features ZF’s adaptive shift control using the TopoDyn topographic and dynamic (it’s in the name) shift programme. Controlled by the driver using a traditional three button selector, it interfaces with engine and vehicle systems by means of a full CAN Bus system.

Like the Raptor and IDD, the MetroDecker has an independent front suspension system, which in this case is the ZF RL75EC with two airbags, two Koni 99 dampers, Knorr Bremse SN7 disc brakes and a steering lock angle of 53/42 degrees. As mentioned, the drive axle is the ZF AV132 portal unit which has a 6.2:1 ratio, four-bag air suspension, four Koni 99 dampers, wide track suspension beams, an anti-roll bar and Knorr-Bremse SB7000 disc brakes. The geared maximum speed is 99kmh and the stall grade, not something I’d normally mention in an evaluation if we weren’t at Millbrook, is 30%.

Other elements of the mechanical specification include a ZF 8098 steering system with integral power assistance, together with a tilt and reach adjustable steering column, 22.5 x 8.25 wheels shod with 275/70R x 22.5 tubeless tyres, a front offside mounted 275-litre stainless steel fuel, 25-litre stainless steel AdBlue tank, and Knorr-Bremse dual circuit SN/SB7 disc brakes with ABS, an air release spring-actuated parking brake, a Knorr-Bremse ZB44 APU air dryer and a Wabco 393cc air compressor. The 24 volt, fully multiplexed, electrical system is the latest generation Actia Actimux centralised system with diagnostics facility. There are two 12 volt 95Ah maintenance free start batteries and two 12 volt 55Ah deep cycle maintenance free main vehicle batteries.

Mounted on the offside is the engine cooling pack with side by side aluminium radiator, charge air cooler and fan system hydraulic oil cooler as well as a large diameter variable speed hydraulic fan. The header tank is stainless steel and fills on the offside. All coolant pipes are stainless steel and hoses are silicon.

While I was taking my pictures of the engine bay, Tim pointed out that the vehicle was running without the usual insulation to the exhaust downpipe and that the area between the turbo and the exhaust was also not insulated as it would be. He also pointed out that there is no sight gauge on the water filler, because they go green and become difficult to see, you just fill it until it is full.

The Mercedes-Benz OM934LA engine is mounted to the left of the engine bay

The Mercedes-Benz OM934LA engine is mounted to the left of the engine bay

During the Millbrook runs regular stops were made at simulated bus stops, complete with poles

During the Millbrook runs regular stops were made at simulated bus stops, complete with poles

GRP with a foam core is used for the between deck side panels

GRP with a foam core is used for the between deck side panels


Though the clear plastic screen is an unwelcome necessity for London operations, the cab itself is relatively spacious. Andrew moved the seat back and had plenty of room. When he first took to the seat he had the impression that visibility wouldn’t be great because of the pillars but once under way he noticed no issue with it and never gave it another thought. ‘When you have the side window open you can still see the mirrors,’ he added.

Operators can specify the colours of the cab mouldings and this had a white binnacle. Andrew felt it was laid out well. He liked the fact that there were no dust traps or switches so that everything can be wiped clean.

The cab showing the coloured binnacle, central display screen and pillar arrangement

The cab showing the coloured binnacle, central display screen and pillar arrangement

Optare were keen that we tested the bus under varied conditions so we started with a lap of the main banked track at 50mph followed by another with regular stops at simulated bus stops. In theory at 50mph in lane two you shouldn’t need to steer but a side wind meant this wasn’t quite the case. Then we went round the outer handling course with windy roads and decreasing radius bends to throw us about a bit after which a thrash down the mile long straight got us up on the limiter at around 58mph before braking smoothly and turning right round the banking to experience a variety of special surfaces designed to send sine waves through the bus. Crossing a few transmission shocks demonstrated the impressive reaction of the suspension before we tried out two different hill routes with long 11.6% gradients, more sharp bends and the chance to show off its uphill reversing capabilities.

Asked what he thought immediately afterwards, Andrew said, ‘It’s very, very stable and very, very nice to drive. The steering is firm and positive; slightly heavy which is how I like it.’

The Topodyn system senses when it is a hill and alters the shift pattern, prompting Andrew to say, ‘it nearly does everything for you. It shifts up quickly’. Even reversing up the 11.6% incline from a standing start it was perfectly happy.

‘It felt relaxed and low revving from the front with no impression of hurriedness’, Andrew observed, ‘the level of power is quite deceptive.’ This despite the fact that it is only a 5.1-litre unit.

Generally on a road test we would look at what the rpm readings were in the different gears and at different speeds, but the MetroDecker tachometer doesn’t give you an rpm figure, just a colour coding relating to the efficiency of your driving at the time.

‘When you get to the bottom of a hill you think it is going to be hard work but it just does it all itself and before you know it you’re at the top. It hasn’t got the feel of a light bus, it feels like a solid heavyweight bus,’ said Andrew.

‘The steering was firm but positive, and because it was firm you could throw it about,’ he said. ‘The ride characteristics may take away some of the negative aspects of a poor driver. The ride over undulations was first class.’

It was noticeable that despite quite sharp turning, often involving a degree of speed, I didn’t hear any squeal from the tyres at any point. Perhaps we should have been rougher with it.

Speaking on the way home, Andrew commented, ‘I was quite taken with it really. You couldn’t fault the driving appeal.’


For the passenger, the ride is extremely good, with even the most violent bump rapidly damped. The bus hits the deformity in the road, whether a bump or a dip, the suspension dips briefly and then the ride is instantly level again. Andrew noted, ‘I’m very impressed with the stable ride in the upper deck. You can get a nodding perception upstairs in a decker and I didn’t notice any of that.’

I was hugely impressed with the lack of vibration evident in the structure at tickover and on the road. None was evident in the windows of the lower deck when moving and upstairs there was very little apart from the open hopper units.

The one exception was the lower deck rear seat where I felt it was both noisy, probably as a result of the missing insulation Tim had mentioned, and there was also a considerable degree of vibration through the base of the seat.

The only place on the bus I encountered significant vibration was sat on the rear lower deck seat

The only place on the bus I encountered significant vibration was sat on the rear lower deck seat

Securing the stanchions directly into the roof structure means that no roof rails are needed

Securing the stanchions directly into the roof structure means that no roof rails are needed

The lower deck. In total the bus has a capacity of 99, 63 of them seated and 22 of these on the lower deck

The lower deck. In total the bus has a capacity of 99, 63 of them seated and 22 of these on the lower deck

The wheelchair bay with glazed partition. The hopper windows will be replaced with higher mounted full width hoppers

The wheelchair bay with glazed partition. The hopper windows will be replaced with higher mounted full width hoppers

In total, the capacity of the bus is 99 passengers, 63 of them seated and 36 standees. There are 41 seats on the upper deck and 22 on the lower. With TfL’s stipulations the seat spacing is very comfortable. Esteban Civic V2 units were used trimmed in blue moquette and I found them perfectly comfortable for short to medium distance journeys. They are not the lightest on the market and a MetroDecker built for durability testing will have a new lighter framed version.

Tim pointed out the indirect LED lighting used throughout, and was especially pleased with the way that passengers do not cast a shadow in the staircase as it lit indirectly rather than from above, providing safety benefits as you can better see where you are placing your feet. With the stanchions locking directly into the structure, there are no rails running the length of the ceiling which, coupled with the indirect lighting from the sides, helps to create an impression of spaciousness.


Behind the rigidity of the bus is the integral structure which is of welded heavy duty semi stainless steel box section construction with anti rust treatment applied to all exposed structural elements and Dinol underseal coating.

Side windows are bonded in place from the outside of the bus. These units are around 80mm shallower than previous designs but you don’t get that impression from the inside because the base is where your arm is and you don’t need to bend down to see out when you stand up. The doors are Ventura units and didn’t rattle or create wind noise.

Unusual to the eye are the upper deck exterior side panels in three sections rather than one stretched panel. This is because they are made of foam cored GRP which insulates more effectively than aluminium. The roof skins and side panels are also GRP, as are the one piece front and rear dome panels. Inside the sidewall panels are worthy of note because although they are in two colours and look as if they are made in sections, the whole of each side from below the window to the floor is a single unit moulded in two colours.

All saloon heating equipment for both decks is located under the rear five place seat on the upper deck. One box with a heater matrix provides the heated blown air for the lower deck or, if the water is turned off, circulates blown air. A separate box with four fans, a heater matrix and a cooling matrix provides the heat, vent and chill facility for the upper saloon.

Over the years the topic of the amount of heat in bus interiors has arisen on a regular basis, notably in the early days of the introduction of the New Routemaster, and following requests from operators the driver has no control over the heating and ventilation system other than in his cab. The whole system, including the upper deck chill facility, is completely automatic, regulated by a single black sensor mounted on an upper deck cove panel. I’m wasn’t completely convinced by this as at times I found the lower deck rather too warm. Tim said there had been an issue with a malfunctioning water shut off valve that could have been the cause. Incidentally, the MetroCity, Versa and Solo have the same HVAC system, minus the chill feature, and when it comes, the 11.1m MetroDecker will also have the chill element. There is quite a degree of cross model commonality, for instance, the Actia ActiMux electrical system is a range wide fitment.

Tim explained that there are a few changes going to be made following experience and feedback, one of the most significant of which is dropping the large hopper windows which, when open sit rather too low for the comfort of passengers in window seats. They will be replaced by more conventional hopper units. Some body panel split lines will change at the front offside and the current screw fittings on the panels over the batteries, radiator and engine access doors are to be replaced by fixings accessed with a T-key. In the cab, a new soft two piece dip moulded column shroud is to be fitted.


There is an inside and an outside to the bus, well yes there is to every bus, but on the MetroDecker the separation between the two is more rigidly defined than ever before on buses, with the possible exception of amphibious ones. Basically, it means that nothing that gets dirty or needs servicing is on the inside. There are none of the traps in the floor you once found. You can even take the shock absorbers off from the outside. The only thing Optare’ engineers were not able to get round was the access to the spring brake hangers, with two little teardrop shaped access points between the over wheelarch seats at the rear of the lower deck, and even then the brake systems themselves do not come into the interior.


The 10.5m two-door launch version of the MetroDecker is squarely aimed at the London market, a significant proportion of which has already been tied up by what TfL now calls the New Routemaster. Nevertheless, it is in the capital that Optare sees the greatest potential, hence the introduction of the TfL specification model ahead of the longer variants.

There is to be an 11.1m long, single door version that, for reasons best known to themselves, Optare refer to as the MetroDecker Retail. That baffles me because many of the same customers buy deckers for their operations within and without London, and surely a name should reflect customer aspirations rather than the organisation of Optare’s sales operation. For Retail think Provincial, with one additional row of seats on each deck. There is also to be an open top version in the near future. Incidentally, the only IDD completed is to have its roof removed and go to Malta as an open topper.

Optare’s Glenn Saint said at the original launch that flywheel type hybrids would be introduced for operation outside London. Beyond this, by the end of next year, a fully electric version is to be made available; technology with which Optare has already enjoyed considerable success in its single deck offerings.

Tim commented, ‘We have looked at the opportunities and requirements of hybrids with zero emissions capabability and decided that we will focus on full EV for city centre and mild (flywheel) hybrid for mixed operation. Both systems must be commercially viable without compromise on passenger capacity.’
Export opportunities add an additional dimension to the equation.

As far as I am aware, no orders have yet been placed for the new models. Officially, Optare will start taking orders at the Euro Bus Expo show in November, though I understand that it has already included it in three tender submissions.

I have not heard a price yet for the product and in truth I don’t really need to because it can’t be more than the competitors are charging if Optare wants to attract volume sales. It will need to attract volume business because its main competitors are already running volume operations with the attendant economies of scale that they bring, and unless Optare can do the same it will be at a commercial disadvantage. Optare has made great strides in streamlining its manufacturing processes which are all now located on the same site, but the competitors have not stood still either.

Last word

Buying double deck buses, especially in quantity, is never simply a case of whether a bus looks nice and is technically up to doing the job. Other factors such as price, support, residual value, fleet standardisation and confidence in the long term future of the manufacturer come into play, and in several of these areas Optare may be at a disadvantage to some of its competitors. It was important therefore that Optare got it right with this product, and delivered something that might persuade hesitant chief engineers that they were not being asked to take too brave a step. The jury is out on whether the MetroDecker has achieved this but it will become clear soon enough when we see whether Optare can succeed in the tendering processes that it has already started submitting the new decker for.

My first impression of the MetroDecker in May was that it was more impressive than I had anticipated and this second encounter has not diminished that view. The stability and ride is excellent and it seems commendably structurally taught, my only reservations being the vibration experienced through the rear seat area and the how high the level of noise at the rear will be once the work being done in that area is complete. Aesthetically it looks attractive, carrying off the use of smaller top deck windows in a way that I am not sure that the Wrightbus product has accomplished. Nothing about the experience of riding on or driving the bus suggests that it is under-engineered and yet the unladen weight is a remarkable 9,980kg, which has to give advantages in fuel economy. There’s a lot there to make it worthy of serious consideration.

Length:    10,500mm
Width:    2,500mm
Height:    4,310mm
Wheelbase:    5,350mm
Front overhang:    2,760mm
Rear overhang:    2,390mm
ULW:    9,980kg
GVW:    18,000kg




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