OC Transpo contract talks broke down Monday after union officials rejected what Ottawa Mayor Larry O'Brien is calling the city's final offer.

"In very, very difficult economic times, we are perplexed that they not only chose to turn down the offer, we are not convinced that they shared that offer with their membership," O'Brien told reporters after a closed door meeting late Monday afternoon.

The union is asking for a 10.5 per cent pay raise over a three-year period, plus concessions on sick days, scheduling, and workplace safety insurance.

The city says it has offered the union a seven per cent wage increase over three years, citing the recent economic downturn for the gap between the city's final offer and the union's demands.

"The union executive determined that our offer - all parts of it - were simply unacceptable," O'Brien told CTV Ottawa.

Union representatives, however, insist the breakdown in talks was not primarily about money.

Breakdown in talks paves way for strike

The situation is now paving the way for more than 2,100 OC Transpo drivers, dispatchers and maintenance staff to walk off the job as early as Wednesday, a move that would cripple the city's public transit system.

Members of the Amalgamated Transit Union, who have been without a contract since April, voted 98 per cent in favour of strike action last week.

Transit users fear strike

The situation has sparked panic among many transit users who say a strike could prevent them from getting to work and other appointments.

"If I don't have the bus then I can't go anywhere, so I hope they don't go on strike," said Mai West, a transit user who gets around in a wheelchair.

"It'd be pretty hard to get around because I don't have a car, so it would be a big problem for me," added another transit user.

Making alternate plans

City officials are warning residents there could be a 20 per cent increase in traffic if a strike goes ahead.

Making matters worse, the Chaudi�re Bridge, a major artery for commuters who travel between Ottawa and Gatineau, remains closed due to structural concerns that were discovered late last week.

The City of Ottawa's contingency plans for a strike include asking people to carpool and stagger work hours. Some downtown bus lanes would be open to traffic and street parking hours would also be extended.

OC Transpo buses provide service to about 350,000 riders on an average day.

With a report from CTV Ottawa's Kate Eggins