An American 2350 crane carries a bucket of concrete to build one of the retaining walls alongside the wider, eastbound lanes for the new highway.
Residents and businesses straddling TH 36 in Maplewood, Minn., a northern suburb of St. Paul, have a mi. (1.6 km) long stretch of highway back in operation after a 75 day closure and a new interchange for their community of 38,000.
After a fast paced, five month construction schedule, road crews built a diamond interchange to replace a busy, signalized, at-grade crossing of the highway by English Street, a primary city arterial.
Bridge crews raised a bridge to carry English Street traffic over the highway while road crews upgraded the highway below to freeway standards. By completing this interchange, MnDOT and the city of Maplewood have eliminated the last signalized intersection on TH 36 in Ramsey County.
This upgrade is part of the Minnesota Department of Transportation’s (MnDOT’s) long term vision to make the highway a “limited access freeway” to improve its safety and traffic flow, according to the MnDOT Web site for this project.
At the same time, the city of Maplewood, which took the lead in this project, has a much safer crossing for English Street, running north and south across the highway and through the city. It is a primary access for the city’s residents and dozens of businesses that line both sides of this stretch of highway.
MnDOT awarded the project to Forest Lake Contracting late last year at a bid cost of $17.3 million. Forest Lake Contracting, based in Forest Lake, Minn., is a local heavy construction and paving company with nearly 40 years of construction experience.
TH 36 stretches for 20 mi. (36 km) between historic Stillwater, one of Minnesota’s first towns located on the St. Croix River bordering Wisconsin, and I 35W, running north out of Minneapolis. The stretch of TH 36 running through northern Ramsey County and a half a dozen suburban neighbors of St. Paul and Minneapolis covers 10 mi. (16 km) between I 35W to the border with Washington County. The highway ends 10 mi. farther to the east at the St. Croix River bordering Wisconsin.
Despite the local inconvenience for area residents and businesses and a lengthy detour for motorists, MnDOT staff received very few complaints during the more than two month road closure.
Closing the road was “something that had to be done. The nice thing about this closure is that the city of Maplewood, probably about a year and a half ago, began holding public meetings to describe the benefits of shutting the road down completely,” said Eric Rustad, MnDOT project engineer. Maplewood staff emphasized that “construction would be completed faster and in one season.”
Maplewood residents and businesses also rode out a similar closure on the same highway just six years ago when its neighbor farther down the highway to the east, North St. Paul, completed a comparable project by closing the highway for most of that summer. That project most likely helped conditioned people to the time benefits of shutting down a road completely to shorten the construction schedule and open it back up earlier, Rustad said.
Other parts of this project included replacing the old railroad bridge carrying a pedestrian/bicycle crossing with a smaller, recreational trail bridge, improving the local road system, adding more storm water pipe and retention ponds and building a noise barrier on one side of the new road while the other side received trees planted on top of a reinforced soil slope.
On a separate contract several thousand ft. west of the interchange, bridge crews removed the original arch bridge carrying TH 36 traffic over a narrow lake channel that connects two of the city’s lakes with a slightly longer bridge to make room to build a pedestrian/bicycle trail below it. This new piece of trail will connect Maplewood’s lakes and park land to a more expansive trail system running throughout St. Paul.
The new English Street bridge is 132 ft. (40 m) long and 73 ft. (22 m) wide. It features two 12. ft (3.7 m) lanes and two, 12 ft. turn lanes for access to and from the ramps of the interchange. Four ft. (1.2 m) shoulders are located on each side of the bridge as well as an 8 ft. (2.4 m) sidewalk on the deck’s west side.
The trail bridge is nearly 200 ft. (61 m) long with a 12 ft. wide walking and bicycle concrete deck. Decorative limestone and brick line the facades of both bridges with ornamental railing and lighting posts mounted on top of their decks.
Road upgrades below the bridge included the addition of a 14 ft. (4.3 m) escape lane on the south side of the highway and a 10 ft. (3 m) shoulder on the north side to complement the two, 12 ft. highway lanes of through traffic in each direction.
Another several thousand feet of local road upgrades on both sides of interchange also were made to improve the local flow of traffic and connection to the interchange.
When construction began in late April, unseasonably cool and wet weather including a couple of 6 in. snow storms slowed excavating crews digging to relocate existing utilities and laying new storm and water mains, Rustad said. The contractor, he added, brought in another excavating crew and worked longer hours to make up for the lost time.
“In the spring we had the rain which slowed down the work that needed to be done before we could close down Highway 36,” said Rustad.
Road crews had to complete this work and the construction of the local road system on the north and south sides of the highway to maintain access to those areas before the highway could be shut down.
“Once we were able to do that, then we were able to get into the 75 day closure for the Highway 36 work,” Rustad said. “And, they used all 75 days to get it done.”
Along a 700 ft. (214 m) section of the road west of English Street, designers took a different approach to support the road bed to add strength to some poor soil conditions. Located under the westbound lanes of this stretch of the highway, MnDOT engineers decided to place a geo foam base to strengthen the road bed.
“In the spring, the water table is high in that area. We needed the strength without the weight,” Rustad said. “So we dug down 7 feet and put in 4 feet of geo foam and put a concrete cap on it and filled it back in. The geo foam layer should prevent our road from buckling or weaving up and down.”
Nearly 3800 cu. yd. (2,907 cu m) of dirt was trucked out to make this cut to prepare it for the geo foam layer and road base. Another 247,741 cu. yd. (189,520 cu m) of common excavation was removed throughout the project area.
Other quantities included 32,230 ft. (9,830 m) of curb and gutter, 6,562 ft. (2,000 m) of sewer pipe, 188,600 lb. (84,870 kg) of reinforcement bars for the English Street bridge and 1,029 ft. (313 m) of pre-stressed beams for the bridge.
During the peak of construction through the summer months, dozens of pieces of heavy equipment roamed up and down the highway corridor now stripped of all its concrete. Over a half dozen Cat backhoes on any given day could be seen digging for the utilities while approximately two dozen Cat scrapers, graders, dozers and rollers prepared the earthen base for the road bed.
A pair of American 7260 cranes, a pair of American 5299 cranes and a 50 ton (45 t) Grove Hydro towered over the site to build the retaining walls and new bridges.
While English Street was a crossing for vehicular traffic, it also was a heavily used pedestrian route. With all the equipment moving up and down the construction corridor and to maintain a safe crossing for pedestrians without a lengthy walking detour, MnDOT staff took a somewhat unique step to create a pedestrian lane across the construction zone.
Posted with stop signs at the temporary pedestrian walk, construction traffic came to a halt for the pedestrians crossing from one side of the road to the other, Rustad said.
Near the west end of the road work and just beyond the full road closure, bridge crews removed the original arch bridge spanning the lake channel and constructed two new bridges for the east and westbound lanes crossing over the water.
Completed under traffic conditions to keep traffic flowing one way in each direction, the construction went well Rustad said and was done in the scheduled 65 days. Building one bridge at a time, crews installed sheet piling and pumped the water out to maintain dry conditions to build the bridge from pre-cast segments.
“We had our pre-cast piling, pre-cast abutments and pier caps and we had inverted T’s for the beams,” Rustad said. “The only thing we cast in place was the bridge deck and barrier.
At a heavily used clover leaf interchange of TH 36 and TH 61 at the west end of the project, crews dug out infiltration ponds on each of the four loops of the interchange to improve the local water resources at the request of the county watershed district.
“We had to shut down each loop as we were putting in the infiltration basins to filter out contaminates flowing in the local lake system,” Rustad said.
All of the major bridge and highway work is done now and just in time for the holiday shopping and travel season and before the snow begins to fly again. Crews will finish out the season with some minor concrete work that will not affect any traffic.