Commuters taking the Newburyport/Rockport Line trains through Saugus on Sunday can expect delays as maintenance crews close down tracks across the Saugus drawbridge.For the entire day Sunday, all Newburyport/Rockport trains will terminate at Lynn and a free bus service will shuttle passengers between Lynn, Chelsea and North Station. Commuters should expect 30 minute delays in each direction.But, as they say, no pain no gain. Engineers for the Massachusetts Bay Commuter Railroad Company are hoping to finish the ongoing repairs Sunday, and if all goes well, by Monday morning, commuters on train and road should have a construction-free trip.The aging bridge is undergoing routine maintenance to make sure it’s holding up well, according to MBCR spokesperson Andrea Wheeler.Due to ongoing maintenance on the bridge, the speed limit for road travelers has been set at 10 mph. But the MBCR expects all commuter rail service to be up when trains start running Monday morning and the speed limit across the bridge will return to its original 40 mph.Expected DelaysDelays of up to 30 minutes are expected on the following trains:INBOUND: 2104, 2156, 2108, 2160, 2112, 2164, 2116, 2168, 2120, 2170, 2124, 2172, 2128OUTBOUND: 2101, 2153, 2105, 2157, 2109, 2161, 2103, 2165, 2107, 2169, 2121, 2173, 2125