Photo of the Week - Week 29:

Conyngham Road's Wright Gemini 3 bodied Volvo B5LH demonstrator bus, DM2, is seen at the Foxborough terminus of Route 151 about to depart for the Dublin Docklands on the 19th July 2014.

Conyngham Road's DM2 entered service on Wednesday the 9th of July 2014. It arrived in Dublin a few months ago and has spent much time in Broadstone, with a few visits to other garages and a period of driver training in Conyngham Road. When it arrived in Dublin it had a London skyline scene which was suitably replaced with a nature scene and an Irish description of the bus on the off-side and an English description on the nearside. The flowers, butterflies and Dandelion florets blowing in the wind may look very familiar to those who recall WH1's livery. It has been strictly allocated to Route 151, providing a suitable fuel use comparison to the latest generation of Dublin's fleet, the GT class. I finally caught up with it on Saturday 19th July and I was quite impressed by it. With increasing European requirements on bus emissions, and the ever increasing price of fuel, Hybrid buses must be the way of the future for Dublin Bus. WH1's unsuccessful spell with the company may well have delayed this fact, but hopefully DM2 will show that the tecnhology has been delveoped much further than the early days of the technology.

A nearside shot of DM2 heading onto Eden Quay on the 19th July 2014.

DM2 is to London specification. Like DM1 it has a reduced seating capacity with large amounts of legroom. But unlike DM1, it has centre-doors. In fact, wheelchair access onto the bus is by this centre doors. The new SG class will look similar externally, having the Gemini 3 body with double doors and an enclosed (non-windowed) staircase, however the wheelchair access will be at the front door as per the Dublin standard. DM2 is equipped with Volvo B5LH hybrid technology, featuring the Volvo I-Sam parallel hybrid system with the Volvo D5K, a 240hp 5 litre Euro 6 engine, and a 160hp electric motor. This electric motor is powered by a 600Volt lithium battery pack. The I-Sam system features stop/start technology. Stopping and starting a large vehicle is by far the most inefficient part of operation for buses. Stop/Start technology has featured prominently in the car industry recently, with cars noticeably switching off their engines when they are stationary at lights. As soon as the accelerator is pressed, the engine restarts. The I-Sam system extends this technology. When the bus comes to a stop the engine is turned off. However, when the accelerator is pressed, the electric motor is engaged. This gets the bus to approximately 10mph, before the diesel motor kicks in. The hand held video below of the DM2 stopping at a bus stop gives an example of this technology. Note that the engine goes off when the bus stops, note that the acceleration sound is purely electric (sounds almost like the DART or LUAS) and then the diesel engine kicks in and everything gets much louder.

The new system is fully Euro 6 compliant, though the fully-diesel DM1 is also compliant with these new strict regulations. Volvo claim that many operators have achieved greater than 30% reduction in fuel comsumption by using the Volvo B5LH, though results are dependent on the operational environment. The 151 is actually a pretty flat route, so results may be promising. I would like to see both demonstrators tested on Route 66A or Route 31. Extreme hills are part of Dublin's network and it would be interesting to see how these buses fair, even if the fuel usage would probably not be comparable to the majority of the network.

DM2 at the East Road terminus of Route 151 on the 19th July 2014.

Photographing the bus is not a simple task. The bus uses the different colour route number display option, the route number being in red while the display is in standard orange. I'm not a fan of the appearance. More importantly the update effect of the two colours is different. The orange flashes on and then off as we are accustomed to. The red route number however scrolls as opposed to turn on/off. In the TV world, this effect was known as interlacing. Only a few on the lines are actually lit up at any one time, potentially as small as 5 in this case, distributed thoughout the number. At the next update, these are turned off and the next lines down from these are lit up and so forth. Thus you will generally get lines through the number in a typical photograph, the thickness of the lines directly proportional to the shutter speed, or how long the camera sensor is exposed. You will notice that the stationary photos in this feature have the route number correctly displayed. By setting the shutter speed to less than 1/100s, the full number will have scrolled through and hence the photo will appear to have the full display lit. However, such shutter speeds are no use to moving shots, hence the shot above at O'Connell Bridge has the distintive lines.

Never a fan of "Not in Service" shots, they don't appear on this site. However this one is actually interesting. It shows that the display is a single-display, not a double display. A section of the display is just red and thus the word "Service" is in both colours.

N.B. This website is not affiliated with Dublin Bus. The information contained herein is intended for enthusiast reference. For all current timetable and route information please refer to the official Dublin Bus Website.