Security at the Western Harbour Tunnel will be stepped up before its grand opening next week following vandalism at Tsing Ma Bridge. Workers were busy making final adjustments to the two-kilometre-long, six-lane tunnel yesterday in preparation for next Wednesday's opening by Chief Secretary Anson Chan Fang On-sang. The Western Harbour Tunnel Company said the work would now involve security upgrades. Electrical wires on the bridge were cut in 32 places on Friday, barely a week before its official opening. Tunnel general manager Erik Cheng Heung-shing maintained security was already strong, but would be stepped up as a precautionary measure before the opening. He refused to give figures, but stated security measures, including manpower, patrol vehicles and surveillance equipment such as cameras and other electronics, would be strengthened. 'We will be increasing the security here although it is already very strong,' he said. Barriers at the tunnel's entrances and booms at its tollgates were kept firmly shut yesterday, with only patrol and maintenance vehicles allowed through. Mr Cheng said the company was offering special deals on prepaid tunnel tickets to attract drivers who might be deterred by the $30 one-way toll - three times that of existing cross-harbour routes. The controversial toll, defended by the company as necessary to pay for the $7.5 billion tunnel, has received the most criticism from taxi unions. Taxis are only allowed to claim an additional $10 from passengers, on top of the toll, to return to their home districts. Unions are angry they will lose business on the route as they receive double toll with other harbour tunnels. The company admitted that doubts over the number of vehicles it may attract had prompted the offer of benefits for private car owners such as a 'buy 10 tickets, get two free' scheme. 'We are also issuing road maps showing drivers the best routes from different parts of Hong Kong to the tunnel entrances,' Mr Cheng said. 'Autopass users will also receive credits.' The company expects about 50,000 to 70,000 vehicles a day on opening, despite its 180,000 daily capacity. Company chairman Robert Adams maintained the absence of congestion would be the tunnel's biggest selling point.