Hidden in the woods just north of Ellsworth Park lie seven crumbling arches that once served as a vital link between Danville and Vermilion Heights. Often considered a dangerous eyesore by local residents, the bridge is barely recognized for its historic significance.
The name Mill Street in reference to this bridge and those that preceded it doesn't come from the name of the road that the bridges carried, but rather from the old name of Logan Avenue.
The bridge was built at a cost of $80,000, replacing the iron Woolen Mill Bridge built in 1890. Construction started on April 1, 1915, and it was opened to traffic by the end of the year. It was about 1,030 feet long from end to end, with the main span 70 feet above the river.
Unfortunately, there were multiple problems that were not taken into account during construction, including a lack of drainage in the hollow approaches, inadequate expansion, an arch rib of one span being built 9 inches higher on one side, a pier built on a coal bed, just to name a few.
By 1918, cracks were seen on the east approach span. In 1921, the bridge needed a major rehabilitation in order to keep the east approach span from collapsing with the rest of the bridge. By 1947, parts of the steel reinforcement had become exposed by falling chunks of concrete, which was the reason for a load limit being imposed in September of that year.
In 1948, the state recommended that it be closed to all traffic, but because of it's importance and as a part of State Route 1, the city compromised and banned trucks from crossing it. Signs were posted at each end of the bridge that set a 10 mile per hour speed limit for passenger cars. It was bypassed in 1950 by the Dan Beckwith Bridge.
The bridge was finally closed to all traffic in May 1960. By that point, rehabilitation was impossible. In December 1965, the city council of Danville authorized action to have the approach spans demolished to keep children off of the bridge, but children would later be reported to pull their bikes up on the bridge with ropes and ride around on the deck.
Although largely forgotten today, the bridge, despite all of its flaws, has stood the test of time, lasting now for over 100 years.
Let us hope that this bridge will someday be recognized for it's historical significance, rare design and former beauty.
Letter to the Editor
December 19, 1921
Memorial Bridge is so near completion, I have been wondering if it is to be brilliantly lighted. I trust that it will be and that better care will be taken of it than the handsome Mill Street bridge. The latter is usually kept lighted on only one side, presumably to save current. That is all right, but if the idea is to save, why not turn the current off at daylight? Last week, and in fact most every day lately, the east side has been lighted not only all night but all day.
It seems to me it would be better to light both sides at night and turn off the current during the day. The lights are getting fewer each day. Many are broken and five of these are the large frosted globes. Probably this is the work of boys who realize they make excellent targets.
These are mentioned merely so that those interested should know of them. It looks bad to visitors here, especially to tourists who have heard much of Danville. It might help some if police officers visited that part of the city occasionally. It may be that at times a "blue coat" does get up this way, but the writer has never seen one and he crosses the bridge four or five times a day. These two bridges are something of which the city should be proud and civic pride should not dwindle after the novelty of the thing has worn off.
Let's have the new bridge lighted, but lighted on both sides at night only, instead of just one side each night and day. What say?
The reason the writer wasn't sure about the lighting on the new Victory Memorial bridge is because lights weren't added until after the bridge was done. Some favored boulevard style lighting and others had a different idea. Cost was also a factor-it took a while to get it sorted out. That's the reason the lights were mounted at curbside, rather than on the bridge rails as on the Mill Street Bridge.
Contributed by N. B. Garver Associate in Civil Engineering, University of Illinois.
The Bridge Street viaduct which was recently completed across the North Fork of the Vermillion River at Danville Ill., is a reinforced concrete structure of the arched rib type with spandrel posts and a girder-and-slab floor It has a total length of 791 ft. 8 in. and provides a 30-ft. roadway and two 5-ft. sidewalks The viaduct consists of nine arch spans of the following lengths: three 53-ft. 4-in. spans, two 80-ft. 10-in. spans, and four 90-ft. spans The maximum height from stream bed to roadway is about 70 ft. The abutments are of the U type, with wings 24 ft. long. The design features of the structure are indicated in the general elevation shown in Fig. 1 (a). The viaduct contains about 5,000 cu. yd. of concrete and about 225 tons of reinforcing steel. The method used in handling materials from the car to their final position in the bridge, is particularly worthy of note, and this feature will be described in detail.
Construction Plant-- The layout of the equipment is shown in Fig. 1 (b). The saw mill is equipped with a band saw, a rip saw, a swinging saw and a boring machine. The power is furnished by a 10-hp. gasoline engine. All forms were cut in the mill and assembled in the open space adjacent to it. A stiff leg derrick (see Fig. 2) equipped with bull-wheel and an 85-ft. boom, was used to unload all materials except lumber and steel bars which were unloaded by hand from cars on the spur track near the storage yards. A 20-hp. steam engine furnished power for the derrick. The wet concrete was transferred from the mixer to the forms by means of an Insly spouting system. Tower No. 1, which was 158 ft. high, was utilized for pouring the west five spans while tower No. 2 had a height of 172 ft. and was used to pour the remainder of the concrete. The position of these towers is shown in Fig. 1 (b). A 30-hp. steam engine was used to operate the skip. The towers (see Figs. 2 and 3) were constructed of 6x6-in. posts, braced in 7-ft. bents by 2x10-in. struts and 2x6-in. diagonals. These members were bolted together with 5/8-in. bolts. The spouting systems were supported by 1-in. steel wire cables attached to the towers. Three sets of 3/8-in. cables were used to guy each tower each set consisting of four cables cables. Elevated sand and gravel bins, with capacities of 45 and 60 cu. yd., respectively, were built. Owl cement was used, the cement being stored in a corrugated iron building located near tower No. 1. The concrete was mixed with a 1/2-cu. yd. Smith mixer water being supplied from the city mains. Pumping was required only in the excavations near the stream. This was done with a 4-in. centrifugal pump driven by a 10-hp. electric motor. The motor and pump were mounted on a frame (see Fig. 4) and were swung over the excavation by means of a chain hoist. By this arrangement it was possible to place the pump at any desired elevation. Gin poles; set on the falsework, were used to hoist the reinforcing steel to place in the arch ribs. This reinforcement consists of four angles laced to form a box section.
Methods of Handling Materials.-- The form lumber steel bars were unloaded from the cars by hand and stored in the yards adjacent to the mill. All bending of bars was done on the work by hand. The sand and gravel were unloaded from cars set on spur track adjacent to the bins and storage spaces. The stiff-leg derrick was equipped with a 3/4-cu. yd. grab bucket, and the gravel or sand was placed either in the bin or storage space, as desired. The reinforcing steel for the arch ribs was also unloaded with the aid of the derrick. Those pieces which were to be used on the east end of the structure were loaded directly on wagons and hauled to that side of the river. In mixing the concrete the proper quantities of sand and gravel were drawn from the bins into a hopper by means of spouts, after which the cement was added. The whole was then spouted from the hopper into the mixer which was located under the platforms shown in Fig. 1. With this arrangement the capacity of the mixer was about one batch per minute. With the exception of the cement no materials were handled by hand. The concrete for the railings was mixed by hand, since this work lagged behind the other parts of the construction. Figure 5 shows some of the railing forms and also some sections of the finished railing.
Order of Construction-- All piers and abutments rest on a thick bed of shale, which lies a short distance beneath the surface of the ground. No difficulties were encountered in excavating for and in concreting the foundations. Construction work began at the west end of the structure and proceeded eastward. The west abutment was first built, then piers Nos. 1 and 2. The falsework and forms were then constructed for the arch ribs of the first span and the concrete then poured. From that time forward the general scheme of construction was to have the falsework and forms for the arch ribs in one span, together with the spandrel posts and deck of the preceding the span, under way at the same time. The arch ribs were poured one day and the deck for the preceding span the following day. When span No. 5 was reached, both the arch ribs and deck were poured. The mixer and hoisting engine were then moved from tower No. 1 to tower No. 2. A 2-ft. gage track had been constructed on a trestle as shown in Figs. 1 and 3, with a down grade toward tower No. 2. The materials were dumped in the hopper at tower No. 1, as formerly, but from there they were placed in cars on the track and transported to the mixer at tower No. 2. There were two cars, each with a capacity of one batch of concrete. These cars were fastened to a cable, as it was first thought that the loaded car going down the incline would draw the empty car back. This arrangement did not prove to be satisfactory, however, so a small steam hoisting engine was used to operate the cable with the cars attached. There were no delays in loading and unloading the cars since each car was loaded from a hopper at the upper end and unloaded into a hopper at the lower end.
Personnel-- The contractor was J. J. Jobst, of Peoria, Ill.; the contractor's superintendent was E. C. Miller; and the contractor's engineer, F. C. Thorpe. J. B. Marsh, of Des Moines, Iowa, was the designer, and W. H. Martin is city engineer of Danville. The writer was consulting engineer for the city of Danville.
By Harlan H. Edwards
City Engineer, Danville, Ill.
Deck expansion of a long concrete bridge in Danville, Ill., with inadequate provision for expansion, water trapped behind abutments and poor concrete were the main causes of incipient failure last fall. It is another example of the lightness with which many public officials regard the importance of adequate and competent engineering control of the construction of municipal structures. Investigations made during the progress of the repairs to the structure disclosed conditions which showed that certain engineering features of the structure as originally planned were neglected or changed and that the character of the concrete work was not of the high class that it should have been.
The Mill St. bridge is a nine-span reinforced-concrete arch viaduct, designed for highway use, having the arch rings of the end spans resting on the abutment walls of the approaches. It was built in 1915 at a cost of about $85,000. As early as three years after the completion of the structure, cracks were noticed in the spandrel columns and arch rings of the east end span, which increased in size and number until action this past summer was imperative to prevent failure of the entire span and probably with it the remaining eight spans of the bridge.
The wing walls were of a cellular type, the wells of which had not been filled, thus lightening the wall considerably. No provision for drainage of seepage water from behind the walls had been made, which resulted in a spreading of the walls of about 3 1/2 in. at the ends, since considerable water was found retained. The fact that the abutment walls were 1/2 in. out of plumb, that the crack of the wingwalls at the approach wall was larger at the top than the bottom, would indicate an overturning movement. The character of the foundation seemed to show that apparently there had been no attempt to bed the bottom of the footing evenly in the shale. Instead, the bed was inclined and part of the footing was founded on coal, 3 ft. thick, immediately above the shale, thus permitting a sliding action.
As shown in Fig. 1, the arch rings were cracked in several places while the crown of the arch was built with a 9-in. greater rise than called for in the design.
The roadway at the curb in the center of the span was humped 1 1/2 in., which probably is the measure of the actual rise of the crown of the arch due to the shortening of the span. The failure of the spandrel column, as shown in Fig. 2 and most strikingly in Fig 3, was due to compression, though they were all out of plumb, due to a thrusting of the arch to the west and an expansion movement of the deck to the east. In warm weather all expansion joints were tight, and in the case of the expansion joints of the span in question, there was apparently nothing built but an ordinary construction joint with no attempt at allowing a space for movement as the span elongated in warm weather. The concrete of all but the rings was noticeably weak and faulty and most of it had received a generous wash-coat of grout to cover up its defects. Care was not used in depositing the concrete in the forms to prevent honeycomb, while the columns especially were lacking in mortar, due either to a mix lean in sand and cement, or more probably due to separation while chuting into place.
The details of the repairs were carried out under the direction of W. C. Reynolds and supervision of S. G. Gould, of Harrington, Howard and Ash, consulting engineers of Kansas City. The abutment wall was stabilized by the construction of large concrete buttresses as shown on Fig. 2. The shattered portions of the spandrel columns were replaced, supporting the deck on timbers which rested on the arch rings. The broken portions of the roadway and fascia beams and the sheared upper portion of the wing walls were also completely replaced, while seven steel-and-concrete ties were placed across the wing walls and approach walls to arrest further spreading. Future expansion was provided for by opening new expansion joints at each end of the span. Drainage holes were provided in the abutment wall to insure future drainage of this part of the structure. The empty wells of the cellular wing walls of the abutment were completely filled and a new substantial sidewalk laid over them.