IPSWICH — The MBTA commuter rail crossing on Topsfield Road is responsible for all recent complaints about train horns, but safety improvements to the one on Washington Street may prove trickier in the long run.

Kurt Anderson, vice president and general manager of Campbell Technology Corp., on Wednesday afternoon presented an outline of the work that needs to be done to design safety improvements at all five of the town's crossings if train whistles are to remain silent, or almost so.

The work needs to be done because the town does not qualify for so-called quiet-zone status, a corridor in which whistles don't have to be blown.

That's due to an accident at the Topsfield Road crossing 41âÑ2 years ago. The selectmen decided last February to request all the crossings be treated as one zone, so the accident means that without improvements, train whistles will sound the entire length of the town, inbound and outbound.

Using aerial views, Anderson went through several scenarios his company might explore to achieve the quiet-zone designation while at the same time hold down costs.

One he depicted on Topsfield Road would involve erecting median barriers on both sides of the track. The existing gates would be kept, and two others added, to prevent drivers from going around the barriers and onto the tracks.

However, that change would mean drivers coming out of the depot parking lot would only be able to turn right, and those coming from downtown would not be able to turn left on Peatfield Street into the lot.

Anderson acknowledged the traffic flow problems that would create and said that will be a consideration when plans are being prepared.

When he got to the aerial photo of Washington Street, Anderson admitted it was going to be challenging. Median barriers won't work because they would completely disrupt traffic. He speculated that a so-called wayside horn, which is less noisy than a train horn, might be used, but it was pointed out there are apartments above the storefronts on Washington Street.

Also tossed around was making Liberty Street one-way from Lord Square to Washington Street and Mineral Street one-way in the opposite direction.

If that were done, one of the existing gates at those crossings could simply be moved across the tracks.

However, Selectman Charlie Surpitski said he suspected there would be considerable opposition to those changes.

The timetable Anderson laid out showed a 24-week horizon before the project could be ready to go to bid, but a pretty solid cost estimate will be needed long before that.

The next big hurdle is a Town Meeting and Town Election vote on spending the money for the improvements, so a cost estimate is needed well before May.