For discussion
on 15 January 1999


Transport Department
New Subhead "Replacement of traffic light signal displays of Light Rail Transit/road junction traffic control system in Tuen Mun and Yuen Long"

    Members are invited to approve a new commitment of $17.4 million for replacing the existing traffic light signal displays of Light Rail Transit/road junction traffic control system in Tuen Mun and Yuen Long.


The existing traffic light signal displays of the Light Rail Transit (LRT)/road junction traffic control system installed in Tuen Mun and Yuen Long are reaching the end of their serviceable life. We need to maintain the reliability of the system to ensure road safety and prevent traffic congestion.


2. We propose to replace the traffic light signal displays of the LRT/road junction traffic control system at an estimated cost of $17.4 million.


3. Road junctions which have an interface with the LRT are controlled by a traffic control system installed between 1988 and 1993 to regulate the LRT and road traffic flows. The system comprises 1 583 on-street traffic light signals with 3 889 light displays and 71 microprocessor-based traffic controllers, detectors and associated cabling.

4. The majority of the traffic light signal displays have been exposed to weathering since they were put into operation. Recently, the Director of Electrical and Mechanical Services (DEMS) assessed the current state of the system and analysed the risk of malfunctioning. He found that most of the basic components of the light displays need to be replaced to avoid upsurge in instances of equipment failure and consequential downtime. The components concerned include signal head assembly with mounting arrangements and backing boards, optical system assembly with lens, reflectors, lampholders, visors and traffic signs and electrical properties like halogen lamps and transformers. They are now showing signs of aging and reducing reliability. For instance, the insulation materials for the transformers of the displays, gaskets of traffic signals and cables which contain organic materials are degenerating and the mechanical and electrical and reflection properties of the displays, such as the audible units, are deteriorating after years of operation. In 1997-98, there were 146 major faults with signal off and the total downtime was about 280 hours on all LRT/road junctions. Causes of failure include faults on the light displays, traffic controllers, pedestrian push-buttons and cables.

5. DEMS advised that delays in the replacement work is likely to give rise to more frequent system failures as more components become defective and malfunctioning. This will in turn cause disruption to the LRT service in Tuen Mun and Yuen Long. Such failures might also pose road safety hazards as the system controls the movement of other vehicles and pedestrians. We therefore consider it necessary to embark upon a replacement programme. This is expected to commence in April 1999 for overall completion in March 2003. Under the programme, we will replace all existing signal components comprising the light displays, pedestrian push-buttons and associated cabling as and when they reach the end of their serviceable life. We will prioritise the replacement programme with reference to the physical conditions and the criticality of the components concerned. The replacement of the light displays and the associated cables would maintain the reliability of the existing on-street junction control equipment for ten more years. To ensure effective traffic management during the replacement period, we will arrange to replace only one set of light display of a traffic light signal for a junction at any one time and will take appropriate traffic congestion mitigating and safety measures.

6. As part of the replacement project, we propose to include the procurement of seven traffic signal controllers as spare equipment to address problem of component obsolescence and make good damage arising from traffic accidents. The spare equipment would be used to replace degraded controllers as and when these are beyond economic repair.


7. We estimate the capital cost of the proposal to be $17.4 million, made up as follows -

$ million
(a)Replacement of traffic signal light displays, pedestrian push-buttons and associated cables 10.5
(b)Procurement of seven additional traffic signal controllers 2.5
(c)Inspection and replacement of underground cables where necessary 1.4
(d)Electrical and Mechanical Services Trading Fund (EMSTF) project management charges 1.4
(e)Contingency [10% of (a) to (d)] 1.6


8. As regards paragraph 7(a), the cost of $10.5 million is for the dismantling and removal of the existing traffic signal light displays and pedestrian push-buttons concerned, the supply and installation of new components in replacement and the associated cabling work.

9. As regards paragraph 7(b), the cost of $2.5 million is for the procurement of seven sets of traffic signal controllers.

10. As regards paragraph 7(c), the cost of $1.4 million is for the labour cost of inspection and testing of existing underground cables including their replacement if found necessary.

11. As regards paragraph 7(d), the cost of $1.4 million is for paying the EMSTF engineering consultancy services. The trading fund will undertake the whole project which involves feasibility study, definition of requirements, preparation of project programme, cost-estimating, tendering, contract administration, site inspection, testing and acceptance, monitoring equipment performance and rectification of defects during the defect liability period. A detailed breakdown of the charges is at the Enclosure.

12. Subject to Members' approval, we will phase the expenditure as follows -

Year$ million
1999-2000 5.1
2000-01 4.1
2001-02 4.1
2002-03 4.1
Total 17.4

13. There will be no additional recurrent expenditure as the proposed commitment is either for replacement or backup purposes.


14. The traffic light signals need to meet stringent specifications in order to ensure safety. The signals need to stand wind velocities up to 160 kilometres per hour in any direction without damage as well as temperatures up to 70 oC. The distribution of light, limit of chromaticity and control of adverse effect due to direct reflection of sunlight on the light displays have to comply with high safety standards. The materials of the casing have to be capable of withstanding corrosion and direct sunlight without deterioration in mechanical strength.


Transport Bureau
January 1999

Enclosure to FCR(98-99)66

Project Management Charges under
Electrical and Mechanical Services Trading Fund
for Replacement of Traffic Light Signal Displays of the
Light Rail Transit/Road Junction Traffic Control System in
Tuen Mun and Yuen Long

$ million
(a) Feasibility study 0.02
(b) Definition of requirements 0.02
(c) Preparation of project programme 0.13
(d) Preparation of estimate and tender documentation 0.13
(e) Tendering assessment 0.20
(f) Contract administration, inspection, testing and acceptance 0.80
(g) Monitoring of equipment performance and defect liability 0.10
Total 1.40