The City of Cambridge began work yesterday to repair water leakage in the Cambridge Street underpass that runs between Harvard Yard and the Science Center.

Conrad C. Fagone, Cambridge commissioner of public works, said yesterday the underpass "couldn't make it through another winter" without the repair job, which will cost about $200,000 and will take four to eight weeks to complete.

Poorly constructed joints in the concrete underpass allow water to "bubble up" into the tunnel, Fagone said. In the winter the water freezes, and creates hazardous driving conditions, he added.

The repairs will cause considerable traffic buildups, Fagone but students passing over the underpass between the Science Center and the Yard will not be inconvenienced.

Traffic, normally accommodated by three lanes in either direction, will be channeled into the westbound side only, while the other section is being repaired. The eastbound side will then be opened for traffic and work will begin on the westbound side.

Fagone said that in the past several attempts have been made at "patching" the leaks, all of which were unsuccessful. Last year, he said, two motorists were almost killed when their vehicles skidded and lost control on the ice.

Funds have been channeled from other projects into the construction and men are working seven days a week to finish at least one side of the underpass before winter.

Fagone said that if the joints in the underpass had initially been installed properly, these repairs would not have been necessary.

Repairs on the tunnel have been an issue between the University and the city for a number of years, and last fall the city threatened to sue Harvard for alleged faulty workmanship in the University's construction of the underpass.