Some history of what I believe to be the first SPUI built

[NE2]

Some history of what I believe to be the first SPUI built (yes, older than the one in Clearwater), from Public Works magazine, 1963. Unfortunately there's no explanation of why the more expensive single-point design was chosen over a cheaper two-point diamond.

Grade Separations Complicate Urban Express Route
C. M. THELIN
Public Works Director, Fort Worth, Texas

THE FORT WORTH Master Street Plan originally completed in 1928, and subsequently revised to fit current traffic conditions, proposed two major north-south thoroughfares through the easterly portion of the city. One of these is the Miller-Oakland project, under construction, and the other is the Beach Street project which will cost over $2,780,000 and connect Mitchell Boulevard on the south with Belknap on the north, a total length of 4 miles. This project now nearing completion is the culmination of many special engineering problems connected with acquisition of right-of-way, the construction of a bridge over the Trinity River, a grade separation over the Dallas-Fort Worth Turnpike, underpasses at the heavily-traveled East Lancaster Street and the double tracked Texas and Pacific Railroad.

The final contract for excavation through the two underpasses, retaining walls, street lighting and paving was awarded to Uvalde Construction Company on the basis of their low bid of $407,000. Capital Improvement Bonds were approved by the citizens of Fort Worth for this project in 1951 and in 1958. Construction was necessary in separate units in order to finance this and other major projects without the necessity of raising the ad valorem tax rate. This necessitated construction over a period of ten years which started in 1952 and which will be completed this year. One other complicated problem consisted of the channelization of traffic and installation of traffic actuated signals at the intersection of East Belknap which involved participation by the state highway department, Haltom City and the City of Fort Worth, and which cost approximately $163,000.

Grade Separation Added
The original bonds voted in 1951 did not provide for a grade separation at East Lancaster which is U.S. Highway No. 80, a major traffic artery east and west through both Dallas and Fort Worth. With the tremendous increase in traffic since 1951, a request was made by the city to the Texas Highway Department for construction of an underpass at this intersection. After a traffic study, the highway department agreed to build the underpass which was recently completed at a cost of approximately $200,000. This underpass necessitated a major revision of the original plans, acquisition of additional right-of-way and construction of long retaining walls for the north approach. The underpass was constructed under contract with the Austin Bridge Company, which built the structure without stopping the flow of heavy traffic on Lancaster Avenue.

Excellent cooperation also was obtained with the Texas Turnpike Authority and the Authority constructed an overpass at Beach Street when the Turnpike was constructed. This is a reinforced concrete four-span continuous structure. The City of Fort Worth awarded a contract to Bruce Construction Company in the amount of $216,000 for construction of a bridge over the Trinity River. This is a continuous steel superstructure 450 feet in length. The T & P Railroad Underpass consists of a three-span structure costing $124,000, which was built by Bridge Builders, Inc., under direct supervision by the railroad. The city retained Carter and Burgess as consulting engineers on the entire project for preparation of the engineering plans and specifications.

M. W. Amis, Jr., chief engineer of the public works department, is responsible to the public works director for the project and J. K. Kimbro, construction engineer, is directly in charge on engineering supervision for the city. A. L. Reader is assistant construction engineer for the city. With the completion of this major project this year, the heavily traveled Riverside Drive will be relieved of congestion, particularly at the Lancaster intersection and better access will be provided between the southeasterly and northeasterly quadrants of the city.

[jakeroot]

Intriguing! I guess the engineer down in Clearwater doesn't get as much credit as previously thought. Though, he definitely mastered the design. Some of the movements here are a little awkward.

And, as a testament to how well SPUI's work, it's still there, working as well as ever. My only gripe is the off-ramp signals are basically impossible to see until the last second.

[jeffandnicole]

A SPUI is basically a regular intersection with a wide median.  Any normal intersection with left turn lanes operates in the same fashion as a SPUI - left turning traffic keeps left of the opposing left turning traffic.  The only reason we don't see more of them is the cost and exaggerated left turning motion needed, since you also have to facture in the wide turning area.

[CapeCodder]

I wonder if the intersection of I-170 and St. Charles Rock Road would be considered an SPUI? I think that's a pretty old interchange.

[usends]

Is that aerial photo showing Lancaster and Beach?  If so, there's also some cool old signage approaching that junction, possibly dating back to when the SPUI was built.  See the last two photos on this page.

[jakeroot]

I wonder if the intersection of I-170 and St. Charles Rock Road would be considered an SPUI? I think that's a pretty old interchange.

It's absolutely a SPUI. Not sure of it's age. Certainly an older example, but I'm not sure when 170 was built past Page Ave. Doubt it's as old as the Clearwater example, and definitely not as old as the Fort Worth example.