Next up for the Kansas Turnpike: Blasting the old Kansas River bridges.

Wednesday evening, crews were busy shifting the turnpike’s eastbound traffic onto a new Kansas River bridge at the northern edge of Lawrence. The traffic was to occupy a single lane on the new bridge as of 5 p.m., then spread out into two lanes later in the night.

The new bridge already started handling westbound traffic last week.

The new bridge is the first of two being built as part of a $130 million project that also includes overhauls of interchanges at Exit 202 and Exit 204.

The first new bridge has been marked with four narrow lanes — two for vehicles heading west, and two for others moving east — to handle traffic until the second bridge can be built.

The second bridge, expected to be done by the end of next year, ultimately will provide three lanes and shoulders for eastbound traffic. The first new bridge then would be dedicated solely for traffic heading west.

To make way for the second new bridge, contractors will clear concrete from the existing spans — each is more than 50 years old, having been there since the turnpike opened in 1956 — so that their steel structures can be removed using explosives. The blasting is set for later this year, possibly the week after Thanksgiving.

The entire project is scheduled for completion by the end of 2011.