I am writing this column on deadline Monday evening, and if I miss it, the worst thing that might happen is that it won't make it into the Tuesday print edition of The Day.

As I aim toward my own routine newsroom deadline, it seems positively trivial compared to the nail-biting deadline the state Department of Transportation and the contractor it has hired to replace the bridge over Oil Mill Road in Waterford is now staring down.

The state, which was to begin narrowing I-95 down to one lane of slow-moving traffic by 8 p.m. Monday, has allotted 34 hours for the replacement of one of four lanes, two north and two south, each 70 feet in length, that make up the bridge over the local road.

The other three are scheduled to be replaced during their own 34-hour time windows, one next week and the others in October. The system, in which pre-built bridge sections are slid into place, is supposed to narrow the disruption time of bridge replacement.

In the best of circumstances, traffic will slow down on the remaining northbound lane of the Oil Mill Bridge Tuesday, and the ensuing highway backup won't make it past the Raymond E. Baldwin Bridge over the Connecticut River, two towns away.

In the event the backup extends farther than the Baldwin Bridge, the DOT's operation center may swing into contingency planning, possibly diverting traffic much farther south on I-95 onto other roads.

What happens, I asked DOT engineer John Deliberto, who is overseeing the complicated, timed choreography of bridge lane replacement, if something goes wrong, if it takes longer than 34 hours?

I could tell from the look on Deliberto's face that taking longer than 34 hours is not really anything anyone wants to think about.

He did say that once they cut into the bridge and start removing it in 8- to-10-foot sections, by the early hours of Tuesday morning, there's really no going back.

"There's a lot to do in 34 hours," he said. "But we have an excellent team in place, a talented contractor and it's all been planned well.

"We do have backups and contingencies if anything goes wrong."

Indeed, the planning includes an hour-by-hour schedule, from the painting of temporary lane lines on the highway surface at the outset, to seating the guide pieces on the roadbed that lead to the new bridge section.

At any given time, they may be ahead or behind schedule, but they will know precisely how well they are doing on time.

One of the quickest jobs on the schedule is sliding the new bridge lane into place, expected to be done between 3 and 4 p.m. Tuesday.

I caught up with Deliberto about five hours before show time, and he looked decidedly calm, given the fact he was about to oversee a disruption of the main highway artery through the Northeast, on a summer day no less.

He had sound engineering answers for every hypothetical alarmist question I could throw at him.

And while the rest of us are just learning that the state has been planning to replace the Oil Mill Road bridge — it's crumbling roadbed and rusted steel are quite apparent from underneath — Deliberto has been on the scene working on the preparation for Tuesday's slide since March.

Three of the four new concrete lane sections have been built on site and stand aligned and ready to slide into place.

The fourth will have to be built after this week, when the median space now occupied by the new northbound fast lane is available to build the slow lane for the southbound side.

Hence the delay for the last two lane replacements until October.

The slide itself will be accomplished with a series of hydraulic machines, four on each side, that will lift the new section and allow it to slide on wheels that are guided by a steel rail.

It's been over-engineered. There are four hydraulic lifts although only three are necessary. They have been tested and work. And there is a backup, a winching system.

I'd say if they switch to winching much past 5 p.m. Tuesday they are probably staring to hit trouble.

Once the new section is in place they will inject grout that expands, to get the level right, to within one hundredth of an inch.

Not only are the deadlines scarier but tolerances are much tighter than they are for journalism.

If you are reading this in print Tuesday, you know I made my deadline.

We'll have to wait and see whether the DOT makes its more onerous deadline.

This is the opinion of David Collins

d.collins@theday.com