IMU (Interurban Multiple Unit)

The IMUs were introduced to provide new rollingstock for the Gold Coast line in 1996. The IMUs are a long-distance optimised version of the SMUs, with extra features such as larger seats, luggage racks, toilets[2]. On the exterior, they are similar enough that Queensland Rail uses identical photos for them on their "Carriage Layouts" section. Another difference is the IMU100 and 120's higher top speeds than their SMU counterparts. I think it is due to a better cooling system for one of the parts (traction motors?), but I can't seem to find the place where I read it again. They also have a higher gear ratio of 1:4.367 vs 1:5.169 on the SMUs (not sure which variant tho, possibly the 100/200?)[4, 10].

Depots: Mayne, Robina, Nambour[11]
Common Lines Served: Gold Coast line, Airport line, Nambour and Gympie North line[11]

Like all other passenger trains operating within the Brisbane Suburban Area, IMUs are fitted with AWS (Audible Warning System). When there is an upcoming restrictive signal (any signal other than green), the driver must acknowledge the warning provided for it within three seconds of its receipt by pressing a button on trains' control panels. If the approaching signal is green, no acknowledgment by the driver is required. Should a train proceed past a restrictive signal without the driver having first acknowledged the warning, the train’s emergency brakes are automatically applied to stop the train. For AWS to operate, both track and rollingstock must be equipped[22].

SMUs, along with IMUs, EMUs, and probably NGRs, are also fitted with door sensors and traction interlocks. The sensors trigger the doors to open if they detect an obstruction upon closing, much like an elevator door. Traction interlocks block power to the trains’ drive motors until all doors have fully closed preventing trains from moving with doors open or obstructed[22].

SMUs, IMUs and ICEs were supplied with rigid steel skirts that protect the wheels and undercarriage equipment. These skirts extend to within approximately 50 mm of the rails, and provide a measure of protection from damage caused by collisions with obstructions at track level[22].

EDI/Bombardier Interurban Multiple Unit 100 series (IMU100)

The IMU100 as seen on QR's Carriage Layouts page

Timeline

Carriage Layout

Source

Carriage 1

Carriage 2

Carriage 3

EDI/Bombardier Interurban Multiple Unit 120 series (IMU120)

The IMU120 as seen on QR's Carriage Layouts page

In 1999, four IMU120 series units (121-124) were ordered for the Airtrain line to Brisbane Airport. They entered service in 2001 and feature high-backed seats with a head cushion as an extension to the SMU220-based seat design[2], as well as a top speed of 140km/h[14]. There is one toilet per unit and the luggage racks are in different configurations than the IMU100s due to interior design differences[2].

While the IMU100s and IMU120s can be used together to form 6-car sets, they no longer do so in revenue service due to electrical and mechanical differences[2]. The IMU120s are fitted with electric plug doors as opposed to air operated plug doors on the IMU100s, they are fitted with one A/C pod per car as opposed to two, and the cooling system has been changed to water cooling which eliminates the noise associated with the traction blower fans[14].

In order to keep the auxiliary converters and systems online through neutral sections of track, IMU120s and SMU220s automatically apply a small amount of regenerative braking while traversing sections at speeds above 20km/h. This reduces the need to rely on the battery system and is also the reason why they maintain full lighting and air conditioning compared to other units in the fleet. However, this can produce a nasty shudder through the train at speeds around 40-60km/h which is mostly unpreventable and varys depending on the unit[15].

Seating Capacity:
76 (IM5121–4: driving motor car); 80 (IM7121–4: trailer car); 59 (IM8121–4: driving motor car)[16]

Timeline

Carriage Layout

Source

Carriage 1

Carriage 2

Carriage 3

Detailed Carriage Layout

Source archived here - see figure A2

Carriage 1

View full image

Carriage 2

View full image

Carriage 3

View full image

EDI/Bombardier Interurban Multiple Unit 160 series (IMU160)

The IMU160 as seen on QR's Carriage Layouts page

The IMU160 Series trains were ordered in 2005 when the Gold Coast line was being upgraded and duplicated, and were introduced in service from 2007 to 2011. The units are virtually identical to the TransPerth B series trains[19], which incorporate a European style Streamlined design, albeit with exposed Air-conditioning Pods[18]. They are also similar to the V/Line VLocity DMU, and Adelaide Metro 4000 class EMU trains with alterations to the headlights to complement with the rest of the Citytrain fleet[2].

They operate as three-car sets, with a driving motor car at each end and a trailer car in the middle. The trailer cars have pantographs but do not have motors[19] These trains are interoperable with the 260 series Suburban Multiple Units as they have almost identical specifications[2].

In 2007, it was discovered during a "1200-point check" that the air conditioning units on top of the carriages had been built 10mm too wide for the loading gauge, sparking concerns over tunnel clearance in a 4m section between Central and Fortitude Valley stations[20].

IMU160s are anticipated to commence retirement in 2049 (as of August 2021)[21].

Seating Capacity:
66 (IM5161–88: driving motor car); 84 (IM7161–88: trailer car); 65 (IM8161–88: driving motor car)[19].

Carriage Layout

Source

Carriage 1

Carriage 2

Carriage 3

IMU160 Virtual Tour

See: https://www.queenslandrail.com.au/Customers/Accessibility/Site%20Assets/Virtual%20Tours/IMU.html

Sources