Most road tunnels you drive through move traffic one way. The Thimble Shoal Tunnel, under the mouth of the Chesapeake Bay, has never done that. It opened in 1964 as a single tube with one lane in each direction, and it still works that way today: oncoming headlights a few feet off your door handle, no shoulder, nowhere to go.<\/p>\n
Virginia has been building the fix since October 2017. A second tube alongside the first, so the old tunnel can go all-northbound and the new one takes everything southbound.<\/p>\n
The machine that dug it is already gone. She broke through on January 27, 2025, came out of a pit in pieces and left the island. The hole is finished, lined and dry.<\/p>\n
You still can’t drive through it, and you won’t be able to until roughly 2028. A good chunk of the reason is an English ship’s anchor nobody knew was down there.<\/p>\n
The Chesapeake Bay Bridge-Tunnel is a 17.6-mile crossing between Virginia Beach and Virginia’s Eastern Shore, and it dips underwater twice along the way. Both tunnels were built as single tubes. Both still carry traffic in both directions.<\/p>\n
Virginia agreed to double the crossing back in 1990. The parallel bridges and trestles opened in 1999. The tunnels never got their twins, which left four lanes above water funneling down into two lanes underneath it.<\/p>\n
The federal Build America Bureau’s project profile for the new tunnel<\/a> puts numbers on what that costs day to day. Disabled vehicles and crashes inside the tube average 25 a year. Oversized loads needing an escort force lane closures 338 times a year. Routine maintenance eats 1,400 hours annually.<\/p>\n Every one of those happens in a tunnel where the opposing lane has nowhere else to be. Roughly four million travelers use the crossing each year.<\/p>\n The machine was named in 2018 by Grace Bentley, then a sixth grader at Nandua Middle School on the Eastern Shore, who won a regional contest with the name of the sea serpent the bay is supposed to be hiding. Naming borers after women is an old tunneling superstition, back to miners asking Saint Barbara to keep the roof up.<\/p>\n Chessie came from Herrenknecht in Germany: an earth pressure balance shield with a 43.5-foot cutterhead and 308 feet of machine trailing behind it. She started boring in February 2023, and CBBT had budgeted about a year for her to cover the mile.<\/p>\n In May, roughly 700 feet and a hundred-odd concrete rings into the drive, pieces of steel started arriving on the conveyor belt.<\/p>\n They were fragments of a ship’s anchor. One recovered piece carried a maker’s mark: W. L. Byers & Co., an anchor foundry that operated in Sunderland, England from the mid-1800s to the mid-1900s. CBBT has said plainly it has no way of knowing how old the anchor is or which vessel lost it.<\/p>\n Michael Crist, the CBBT’s executive director of infrastructure, put it at around 10 feet with flukes three or four feet each, and somewhere between three and a half and five tons. None of it showed up in the pre-construction survey. He told Chesapeake Bay Magazine<\/a> the thing was buried under large rocks, and that they missed it.<\/p>\n Ground surprises are the standing risk in this work. It is exactly why the crews on New York’s $16 billion Hudson rail tunnel<\/a> are freezing the soil solid before they bore the Manhattan side.<\/p>\n You cannot reverse a tunnel boring machine. It builds the tunnel wall behind itself as it goes, which is why Sydney had to cut two 1,100-ton borers into pieces<\/a> and lift them out at 3am when they finished. Chessie was sitting under the Chesapeake with a chewed-up cutterhead and a dead end behind her, so the contractor went to her.<\/p>\n The answer was a safe haven: a treated block of ground built in front of the machine, stable enough that people could work at the face without the bay following them in. Bulkheads and air locks at the front let crews in under compressed air to clear the remaining debris and see what the steel had done.<\/p>\n The inventory came back ugly. 389 of the cutterhead’s 442 tools needed replacing, and each one weighs about 150 pounds. Another 48 wear plates went with them. All of it was swapped out by hand, in front of the cutterhead, under the floor of the Chesapeake Bay.<\/p>\n The machine itself got off lightly. A full inspection of the mechanical and drive systems turned up no further damage. Tunneling restarted on April 8, 2024, and CBBT’s own project newsletter<\/a> puts the total schedule cost of that anchor at 241 days.<\/p>\n As stoppages go it was still the cheap version. A German machine called Paulina sat under the Swiss Alps for 329 days<\/a> after 2,000 cubic meters of rock came down around her.<\/p>\n Once she was running again, Chessie averaged about 50 feet a day on a line more than 50 feet below the seabed, according to Engineering News-Record<\/a>. She finished with more than 6,300 feet mined, around 500,000 cubic yards of soil removed and close to 10,000 precast concrete segments built in behind her, ten segments to a ring, 10 tons apiece.<\/p>\n She reached the receiving pit on Two Island on January 27, 2025, then stopped while crews pulled the temporary bracing struts out of the receiving wall, and ground through the last of it two days later.<\/p>\n Count only the months she was actually mining rather than parked and it comes to roughly a year, which is about what CBBT planned for in the first place. The digging was never the problem. Granite boulders armoring the old man-made islands had already slowed the excavation of her launch and receiving pits, and then a single lost object took eight months of the schedule on its own.<\/p>\n CBBT’s spring 2026 project update<\/a> is the clearest look at what a finished bore actually is before it becomes a road, and it is not close to done.<\/p>\n Tunnel ballast placement is complete. Passive fire protection boards are up along the crown, sitting between the concrete segments and the first heat of any future fire. Crews are laying drainage pipe in a trench in the floor of the egress corridor, the full-length passage that serves as maintenance access and as a refuge if something goes wrong down there.<\/p>\n The low-point pump room in the middle of the tunnel has been sealed under a new structural concrete roadway. The portal pump rooms below the roadway at each end are poured. At the portals, the orange waterproofing membrane has to go on before the concrete walls can even be formed.<\/p>\nChessie got about 700 feet in and found something nobody had surveyed<\/h2>\n
Somebody had to change 389 tools by hand, under the bay<\/h2>\n
The boring turned out to be the fast part<\/h2>\n
Right now the tunnel is mostly pumps, concrete and fireproofing<\/h2>\n