Jump to content

I-35W Mississippi River bridge: Difference between revisions

From Wikipedia, the free encyclopedia
Content deleted Content added
Gwen Gale (talk | contribs)
m verb tns
MplsNarco (talk | contribs)
Lock and Dam #1 is incorrect. It is technically not a numbered dam; instead, it is known as the St. Anthony Falls Upper Lock and Dam.
Line 75: Line 75:
By [[August 2]], rescue efforts had shifted to recovery of fatalities with several vehicles known to be trapped under the debris and at least eight persons reported missing.<ref>{{cite news | title = 4 Collapse Victims Identified, 8 Still Missing | publisher = WCCO.com | date = 2007-08-02 | url = http://wcco.com/topstories/local_story_213191448.html | accessdate = 2007-08-03 }}</ref><ref name="Strib080107" /><ref>{{cite web|url=http://www.orlandosentinel.com/news/nationworld/orl-bk-bridge0801,0,1607514.story?coll=orl-newsaol-headlines|title=Interstate bridge collapses in Minnesota, at least 9 dead | publisher=Star Tribune| date=2007-08-02 | accessdate = 2007-08-02}}</ref> The [[U.S. Army Corps of Engineers]] lowered the river level using the [[Lock and Dam No. 1, Mississippi River|Ford Dam]] (located approximately 3 miles (5 km) downriver at West River Road and East 50th Street) by two feet (60 cm) on [[August 2]] to allow easier access to vehicles in the water; lowering it any more than that would actually create a more dangerous environment for divers.<ref>{{cite web |url=http://www.startribune.com/10204/story/1339966.html|title=River level to be lowered to help with recovery| publisher=Star Tribune| date=2007-08-02 | accessdate = 2007-08-02}}</ref><ref>Jeff Horwich, [http://minnesota.publicradio.org/display/web/2007/08/02/rescue_efforts/ Recovery effort cautious, deliberate], [[Minnesota Public Radio]], [[August 2]], [[2007]], Retrieved [[August 2]], [[2007]]</ref>
By [[August 2]], rescue efforts had shifted to recovery of fatalities with several vehicles known to be trapped under the debris and at least eight persons reported missing.<ref>{{cite news | title = 4 Collapse Victims Identified, 8 Still Missing | publisher = WCCO.com | date = 2007-08-02 | url = http://wcco.com/topstories/local_story_213191448.html | accessdate = 2007-08-03 }}</ref><ref name="Strib080107" /><ref>{{cite web|url=http://www.orlandosentinel.com/news/nationworld/orl-bk-bridge0801,0,1607514.story?coll=orl-newsaol-headlines|title=Interstate bridge collapses in Minnesota, at least 9 dead | publisher=Star Tribune| date=2007-08-02 | accessdate = 2007-08-02}}</ref> The [[U.S. Army Corps of Engineers]] lowered the river level using the [[Lock and Dam No. 1, Mississippi River|Ford Dam]] (located approximately 3 miles (5 km) downriver at West River Road and East 50th Street) by two feet (60 cm) on [[August 2]] to allow easier access to vehicles in the water; lowering it any more than that would actually create a more dangerous environment for divers.<ref>{{cite web |url=http://www.startribune.com/10204/story/1339966.html|title=River level to be lowered to help with recovery| publisher=Star Tribune| date=2007-08-02 | accessdate = 2007-08-02}}</ref><ref>Jeff Horwich, [http://minnesota.publicradio.org/display/web/2007/08/02/rescue_efforts/ Recovery effort cautious, deliberate], [[Minnesota Public Radio]], [[August 2]], [[2007]], Retrieved [[August 2]], [[2007]]</ref>


Sequential images of the collapse were taken by a [[security camera]] located at the Army Corps of Engineers control house for [[Lock and Dam No. 1]], and leaked to [[CNN]].<ref>{{cite web | publisher = [[CNN]] | url = http://www.cnn.com/video/#/video/us/2007/08/02/vosli.mn.i35w.bridge.collapse.side.view.cnn?iref=mpvideosview | title = Video captures bridge collapse | date = [[August 2]] [[2007]] | accessdate = 2007-08-02 }}</ref><ref>{{cite web | publisher = WTOP | url = http://www.wtopnews.com/index.php?nid=114&sid=1208101 |
Sequential images of the collapse were taken by a [[security camera]] located at the Army Corps of Engineers control house for [[Lock and Dam No. 1|St. Anthony Falls Upper Lock and Dam]], and leaked to [[CNN]].<ref>{{cite web | publisher = [[CNN]] | url = http://www.cnn.com/video/#/video/us/2007/08/02/vosli.mn.i35w.bridge.collapse.side.view.cnn?iref=mpvideosview | title = Video captures bridge collapse | date = [[August 2]] [[2007]] | accessdate = 2007-08-02 }}</ref><ref>{{cite web | publisher = WTOP | url = http://www.wtopnews.com/index.php?nid=114&sid=1208101 |
title=CNN Gets Beat on Video of Collapse|date = [[August 2]] [[2007]] |accessdate = 2007-08-02}}</ref>
title=CNN Gets Beat on Video of Collapse|date = [[August 2]] [[2007]] |accessdate = 2007-08-02}}</ref>



Revision as of 03:27, 3 August 2007

Mississippi River bridge
The bridge in May 2006
Coordinates44°58′44″N 93°14′42″W / 44.97889°N 93.24500°W / 44.97889; -93.24500
LocaleMinneapolis, Minnesota, U.S.
Maintained byMinnesota Department of Transportation
ID number9340[1]
Characteristics
DesignDeck-arch truss bridge
Total length1,907 feet (581 m)
Width108 feet (33 m)
Longest span458 feet (140 m)
Clearance below64 feet (19.5 m)
History
OpenedNovember 1967
ClosedAugust 1, 2007
Statistics
Daily traffic141,000[2]
Location
Map

The Interstate Highway 35W (I-35W) Mississippi River bridge (sometimes called Bridge 9340), built in 1967 by the Minnesota Department of Transportation (MN/DOT), was an eight-lane, 1,900-foot (579 m) deck-arch truss bridge that carried Interstate Highway 35W across the Mississippi River in Minneapolis in the U.S. state of Minnesota. Located in Hennepin County in the Minneapolis-Saint Paul metropolitan area,[3] this north-south bridge connected the Minneapolis neighborhoods of Downtown East and Marcy-Holmes. Before its collapse this was Minnesota's busiest bridge[4] with 141,000 vehicles crossing the steel arch span every day.[2]

On August 1, 2007, the entire bridge collapsed from abutment to abutment, falling into the river and onto its banks during the weekday afternoon rush hour. There were at least 79 injuries and 4 deaths, with possibly 20-30 people still missing.[5]

Location

Map showing bridge location in red

The north bank span of the I-35W Mississippi River bridge was anchored northwest of the University of Minnesota East Bank campus, and the south span of the bridge rests on the former Minneapolis Gas Works manufactured-gas plant site,[6] just northeast of the Metrodome. Along with the Plymouth Avenue Bridge, the I-35W bridge bounds the Mississippi Mile riverfront parkland.[7] Saint Anthony Falls and the Stone Arch Bridge are to the north of the I-35W Mississippi River bridge.[8] In June 1996, whitewater enthusiasts proposed a paddle-sports park on the river's east bank between Stone Arch Bridge and the I-35W bridge.[9]

The I-35W bridge shares the same mile (1.6 km) of the Mississippi as two of Minneapolis' other spectacular catastrophes: the explosion of the Washburn "A" Mill in 1878[10] and the 1869 collapse of the Hennepin Island tunnel,[11] which nearly destroyed St. Anthony Falls and resulted in cementing over the only major waterfall on the Mississippi River.[12]

History

Aerial view looking westward; from bottom to top, the I-35W bridge, the Lower Saint Anthony Falls dam, the Stone Arch Bridge, Saint Anthony Falls, and finally the Third Avenue Bridge (Army Corps of Engineers)

The I-35W Mississippi River bridge, in its entirety, was over 1,900 feet long (579 m). It consisted of fourteen spans; five south approach spans, three main spans, and six north approach spans. The three main spans were of deck truss construction while all but two of the approach spans were steel girder construction with the remaining two approach spans being concrete slab construction. The bridge was designed to 1961 American Association of State Highway Officials (AASHO) Standard Specifications.[13]

The I-35W bridge had no piers located upon the riverbed. To avoid having piers interfere with river navigation, the bridge was built with a single, 458-foot (140 m) steel arch over the 390-foot-(119 m)-wide navigation channel. The two main support piers, each with two load-bearing concrete pylons, were located on the banks of the river. [5] [14]

Two sets of locks and dams just upriver of the bridge were constructed a few years earlier to allow passage past Saint Anthony Falls. The bridge was one of the widest in the Twin Cities area and provided an important link for I-35W traffic.

Toxic waste

View from West River Parkway (the south end)

During the 90 years prior to the bridge's construction and opening in 1967, Minnegasco's predecessor, Minneapolis Gas Works,[15] operated a coal-to-gas processing plant on a 20-acre (8 ha) tract on the west bank of the Mississippi, under what was the Interstate Hwy. 35W bridge on the south side of the river.[16][6] Minnegasco, which now is part of CenterPoint Energy,[17] demolished the plant in the 1960s since natural gas made the coal-to-gas processing plant obsolete.[16] Half the site was sold to Continental Oil Co., who stored and processed petroleum products on the site for 20 years.[16]

In March 1989, there was discussion of easing traffic congestion by opening two previously closed lanes leading to the bridge.[18] William Crawford, the district engineer in charge of the project, believed that there would be subsoil problems at the north end of the bridge if the lanes were opened.[18]

The long-term industrial use of the area resulted in a toxic-waste dump below the Interstate Hwy. 35W bridge and a 1991 lawsuit.[16] The 15,000 tons (13,600 t) of contaminated soil were removed from below the bridge, ground up with wood chips, and burned as a fuel additive for a power plant between 1993 and 1998 at a cost of US$30 million.[15][19][20][21]

Black ice

In February and December 1996, the Interstate Hwy. 35W bridge over the Mississippi River east of downtown Minneapolis was identified as the single most treacherous cold-weather spot in the Twin Cities freeway system, due to a thin layer of black ice causing spinouts and collisions on the bridge.[22][23] By January 1999, the state Transportation Department began testing liquid magnesium chloride and a mixture of magnesium chloride and a corn-processing byproduct to see whether either would reduce the black ice that appears on the bridge during the winter months.[24] In October 1999, the state embedded temperature-activated nozzles in the bridge deck to spray the bridge with liquid potassium acetate to keep the area free of winter black ice.[25] The system came into operation in 2000.[26][27]

Structural reviews

In the years prior to the collapse, several reports citing problems with the bridge were issued. In 1990, the federal government gave the I-35W bridge a rating of "structurally deficient," citing significant corrosion in its bearings. [28] A 2001 Minnesota Department of Transportation report indicated weakness at the joints of the steel that held the concrete deck above the river, due to "unanticipated out of plane distortion" of the steel girders. The report also noted a concern about lack of redundancy in the main truss system,[13] which meant the bridge had a greater risk of collapse in the event of any single structural failure. In 2005, the bridge, along with over 70,000 other US bridges[29], was rated as "structurally deficient" and in possible need of replacement, according to the US Department of Transportation's National Bridge Inventory database.[30] In a subsequent report, an inspection carried out June 15, 2006 found numerous problems, including fatigue cracking.[31]

Other topics of concern are the water erosion around the north piers (which were partially toppled in the collapse), steel substructure defects (especially near the south piers which toppled sideways in a scissors motion), problems with the bridge de-icing system,[32] thermal cycling of the structure and recent heavy rains and flooding on the I-35W highway.[33]

Collapse

Collapsed bridge on 1 August 2007, looking southward.

In the weeks prior to August 1, 2007, Mn/DOT conducted repairs on the surface of the bridge and, shortly before the incident, announced that it would reduce traffic flow on the bridge to one lane in each direction during the late evenings of July 31 and August 1 to accommodate construction.[34][35][36]

At about 6:05 PM, CDT on August 1, 2007, a large portion of the bridge collapsed into the river and onto the riverbanks below.[35][37] The bridge's collapse sent more than 50 vehicles, their occupants and several construction workers into the river or to its banks.[5][35][38] Several vehicles caught fire among the debris, including a semi-trailer truck, forcing fire crews to route hoses from several blocks away.[5] In addition, a portion of the bridge fell onto a freight train parked[citation needed] beneath the structure.[39] No one was on the train;[citation needed] the line carries no passenger trains.[40] Drivers were stranded on parts of the collapsed bridge that were not submerged.[41] Sixty children, aged four to 14, were riding a school bus that was on the bridge at the time of the collapse, returning from a weekly field trip to a water park. The bus made it most of the way across the bridge before the roadway collapsed underneath the vehicle.[42] Reports indicate that all children on the bus escaped safely, but one youth worker was severely injured.[43]

By August 2, rescue efforts had shifted to recovery of fatalities with several vehicles known to be trapped under the debris and at least eight persons reported missing.[44][35][45] The U.S. Army Corps of Engineers lowered the river level using the Ford Dam (located approximately 3 miles (5 km) downriver at West River Road and East 50th Street) by two feet (60 cm) on August 2 to allow easier access to vehicles in the water; lowering it any more than that would actually create a more dangerous environment for divers.[46][47]

Sequential images of the collapse were taken by a security camera located at the Army Corps of Engineers control house for St. Anthony Falls Upper Lock and Dam, and leaked to CNN.[48][49]

Consequences

Officials with the National Transportation Safety Board (NTSB) have initiated an investigation into the cause of the collapse. Despite multiple reports of questionable structural integrity,[13] the official cause of the collapse has yet to be determined. Officials with the Department of Homeland Security stated there was no indication of terrorism being involved.[37]

Federal officials also advised states to conduct inspections of the 700 bridges with similar construction styles in the US.[14]

Reaction

Governor Tim Pawlenty made a public statement to the effect that "no structural deficiencies were identified" in reference to the bridge inspection reports of 2005 and 2006[50].

Effect on sporting events

The Minnesota Twins, a Major League Baseball team, chose to play its scheduled Wednesday night home game against the Kansas City Royals at the Metrodome. Public safety officials told the team that canceling the game could hamper rescue and recovery efforts, as a cancellation would send 20,000 to 25,000 people back into traffic.[51] I-35W runs behind the Metrodome, just blocks from the collapsed bridge. A moment of silence was held for the victims of the collapse before the game.[51] The team postponed their game against the Royals scheduled for Thursday, August 2. Groundbreaking ceremonies for the team's new stadium (also located in downtown Minneapolis) had been scheduled to take place after the game, but were postponed to an undetermined future date.[51][52]

Effect on navigation and traffic

The collapse of the bridge has affected rail, river and road transit. Pool 1, created by Ford Dam, is closed to river navigation between mile markers 848 to 857.[53]

This bridge carried nearly 25% of the traffic into downtown Minneapolis. The Minnesota Department of Transportation published detour information, and made real-time traffic information available for callers to 511. The designated alternate route in the area was Highway 280 via Interstate 94. Since I-35W was closed between Stinson Boulevard and I-94, MN 280 was nominally converted to a temporary freeway with all at-grade access points closed. From the northern suburbs, Interstate 694 was a recommended alternate route. Extra Metro Transit buses were added from park-and-ride locations in the northern suburbs during the rush hours. Long-distance traffic north or south through the Twin Cities via Interstate 35 was advised to take Interstate 35E through St. Paul.[54] If the bridge is not replaced by the summer of 2008, it could have a significant effect on logistics and planning for the 2008 Republican National Convention.[55]

Possible replacement

Rep. Jim Oberstar, a Minnesota member of the Minnesota Democratic-Farmer-Labor Party who chairs the House Transportation Committee, introduced a bill to direct a minimum of US$250 million to help replace the bridge.[56][57] President Bush has vowed to provide financial assistance for the reconstruction effort.[58]


See also

Related infrastructure
Other bridge and overpass disasters

References

  1. ^ "Bridge was rated 'structurally deficient' in 2005". Star Tribune. 2007-08-02. Retrieved 2007-08-02. {{cite news}}: Check date values in: |date= (help)
  2. ^ a b "2005 Traffic Volumes" (PDF). Minnesota Department of Transportation. 2005. Retrieved 2007-08-01.
  3. ^ "Google Maps".
  4. ^ Associated Press, Minn. Bridge Problems Uncovered in 1990, 2 August 2007, retrieved 3 August 2007
  5. ^ a b c d "At Least 7 Dead in I35 Bridge Collapse". WCCO News. 2007-8-1. {{cite news}}: Check date values in: |date= (help)
  6. ^ a b Meersman, Tom. (March 23 1993) Star Tribune Minnegasco has a legacy of waste - to burn. Section: News; Page 1B.
  7. ^ Flanagan, Barbara. (August 26 1988) Star Tribune Sheba the donkey is off Nicollet Island, but on pictorial map of it. Section:News; page 3B.
  8. ^ Brandt, Steve. (May 31 1989) Star Tribune Hennepin considers buying Stone Arch bridge. Section news; Page 7B.
  9. ^ Nelson, Tim. (June 12 1996) St. Paul Pioneer Press Churning up the river. Visions of an urban paddle-sports park could bring white water to the Mississippi. Section: Metro; Page 1B.
  10. ^ "Washburn 'A' Mill Explosion". Minnesota Historical Society. Retrieved 2007-08-02.
  11. ^ "Falls of St. Anthony". A History of Minneapolis. Minnesota Public Library. Retrieved 2007-08-02.
  12. ^ Parker, Dick. (October 30, 2006) Star Tribune Retro: Saving St. Anthony Falls in 1869. Mississippi gorge almost eats Minneapolis' heart. Section news; page 3B.
  13. ^ a b c Fatigue Evaluation of the Deck Truss of Bridge 9340, Minnesota Department of Transportation, Report #MN/RC-2001-10, March 2001, retrieved from Minnesota Local Road Research Board website
  14. ^ a b "U.S. officials urge quick inspections of bridges similar to Minneapolis span". 2007-08-02.
  15. ^ a b Meersman, Tom. (April 28 1993) Star Tribune Citizens board OKs NSP plan to burn tainted soil. Section News; Page 5B.
  16. ^ a b c d Rebuffoni, Dean. (December 16 1991) Star Tribune Old plant site spawns environmental, legal mess. Now the questions is: Who will pay for riverfront cleanup? Section: news; Page 1B.
  17. ^ Kane, Lucile M. (1966, revised 1987). The Falls of St. Anthony: The Waterfall That Built Minneapolis. St. Paul, Minnesota: Minnesota Historical Society.
  18. ^ a b Cassano, Dennis. (March 17 1989) Star Tribune. Perpich orders study of closed I-35W bridge lanes. Section News, Page 8B.
  19. ^ Meersman, Tom. (July 7 1993) Star Tribune Minnegasco starts cleaning up riverside waste today. Section news; Page 3B.
  20. ^ Meersman, Tom. (March 21 1996) Star Tribune The environment. Digging up a new riverside. Minnegasco's cleanup of contaminants along the Mississippi will clear the way for a north-south parkway link. Section: news; Page 3B.
  21. ^ Ison, Chris. (March 21 1999) Star Tribune New pollution-agency chief was at center of cleanup flap. Section news; Page 1B.
  22. ^ Blake, Laurie. (February 3 1996) Star Tribune February deep freeze. Black ice makes I-35W bridge treacherous. Section: news; Page 10A.
  23. ^ von Sternberg, Bob. (December 27 1996) Star Tribune Minnesota is one big deep freeze. What is the sound of a cold record shattering? It's the sound of silence from dead motors, of crumpling metal on icy roads, of resigned grumbling. But take heart - it'll warm up. Section News; page 1A.
  24. ^ Blake, Laurie. (January 21 1999) Star Tribune State hopes to speed up north-metro lane project. But it clashes with Met Council over whether addition to interstate should be for car pools. Section news; Page 2B.
  25. ^ Blake, Laurie. (October 19 1999) Star Tribune I-35W bridge getting de-icer system. Unit will target ice before it can form. Section news; Page 1A.
  26. ^ Blake, Laurie. (January 13 2000) Star Tribune Met Council will survey our citizens' travel habits. Study will include trip numbers and times, speed of drivers and waits at ramp meters. Section news; Page 2B.
  27. ^ Blake, Laurie. (February 3 2000) Star Tribune Richfield may face traffic challenges; How will I-494 accommodate Best Buy's 5,000 commuters? Section news, page 2B.
  28. ^ Minn. bridge problems uncovered in 1990 August 2, 2007
  29. ^ Associated Press, More than 70,000 bridges rated deficient, 2 August 2007, retrieved 2 August 2007
  30. ^ Associated Press, Hopes Dim in Minneapolis for Survivors, 2 August 2007, retrieved 2 August 2007
  31. ^ "Bridge Inspection Report 06-15-06" (PDF).
  32. ^ "I-35W & Mississippi River Bridge Anti-Icing Project" (PDF).
  33. ^ "Inspections, reports raise questions about bridge's safety". Pioneer Press. 2007-08-02. Retrieved 2007-08-02.
  34. ^ "35W Bridge Collapses". KARE11. 2007-8-1. Retrieved 2007-08-01. {{cite news}}: Check date values in: |date= (help)
  35. ^ a b c d I-35W bridge collapses, Star Tribune, August 1 2007.
  36. ^ "I-35W will narrow to one lane in Minneapolis over two nights, [[July 31]] and [[August 1]]" (Press release). Minnesota Department of Transportation. Retrieved 2007-08-01. {{cite press release}}: URL–wikilink conflict (help)
  37. ^ a b "Minneapolis bridge collapses during rush hour". MSNBC. 2007-08-02. Retrieved 2007-08-02. {{cite news}}: Check date values in: |date= (help)
  38. ^ "35W bridge over Mississippi collapsed". 5 EYEWITNESS NEWS. 2007-08-01. Retrieved 2007-08-01.
  39. ^ "4 Collapse Victims Identified, 8 Still Missing". WCCO.com. Retrieved 2007-08-02. {{cite news}}: Text "date 2007-08-02" ignored (help)
  40. ^ "Minneapolis bridge collapses, seven dead". The Age. 2007-08-01. Retrieved 2007-08-01.
  41. ^ Freeway bridge collapses into river during rush hour in Minneapolis, Minnesota Star Tribune, August 2 2007.
  42. ^ AP, School bus barely escapes bridge collapse, Fox 19, August 1 2007
  43. ^ Star Tribune, School Kids on crashed bus reunited with families, Minneapolis Star Tribune, August 2 2007
  44. ^ "4 Collapse Victims Identified, 8 Still Missing". WCCO.com. 2007-08-02. Retrieved 2007-08-03.
  45. ^ "Interstate bridge collapses in Minnesota, at least 9 dead". Star Tribune. 2007-08-02. Retrieved 2007-08-02.
  46. ^ "River level to be lowered to help with recovery". Star Tribune. 2007-08-02. Retrieved 2007-08-02.
  47. ^ Jeff Horwich, Recovery effort cautious, deliberate, Minnesota Public Radio, August 2, 2007, Retrieved August 2, 2007
  48. ^ "Video captures bridge collapse". CNN. August 2 2007. Retrieved 2007-08-02. {{cite web}}: Check date values in: |date= (help)
  49. ^ "CNN Gets Beat on Video of Collapse". WTOP. August 2 2007. Retrieved 2007-08-02. {{cite web}}: Check date values in: |date= (help)
  50. ^ "Governor denies that bridge was structurally deficient".
  51. ^ a b c "Twins postpone Thursday's game after bridge collapses near Metrodome". ESPN.com. 2007-08-01. Retrieved 2007-08-02. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  52. ^ "Twins postpone Thursday's game after bridge collapses near Metrodome". KARE11. 2007-08-01. Retrieved 2007-08-02.
  53. ^ Coast Guard Responds To Minnesota Interstate Bridge Collapse, Press Release, U.S. Coast Guard, August 1, 2007, retrieved August 2, 2007
  54. ^ "Transit Alternatives To I-35W". WCCO. 2007-08-02. Retrieved 2007-08-02. {{cite web}}: Check date values in: |date= (help)
  55. ^ The New York Times, GOP Summer Meeting in Minnesota Clouded by Bridge Tragedy, 2 August 2007, retrieved 2 August 2007
  56. ^ "Sen. Reid: 'Too Soon' For $250M Fund Request". WCCO. 2007-8-2. Retrieved 2007-08-02. {{cite news}}: Check date values in: |date= (help)
  57. ^ "House panel approves bill to provide $250 million for bridge". examiner.com. 2007-8-2. Retrieved 2007-08-02. {{cite news}}: Check date values in: |date= (help)
  58. ^ Bush says feds will help rebuild Minneapolis bridge August 2, 2007
  • Costello, Mary Charlotte (2002). Climbing the Mississippi River Bridge by Bridge, Volume Two: Minnesota. Cambridge, MN: Adventure Publications. ISBN 0-9644518-2-4. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)