June 11, 2010
by Randy Young
In a surprising turn of events, we learned at Thursday's public meeting that the city has suspended all work on the FM 518 bypass until several other alternatives can be properly evaluated. City officials readily admitted they simply did not have sufficient data to justify spending more than $17 million on the proposed bypass.
Peter Polk, a consulting engineer, presented several different options including the proposed bypass. He used computer simulations to predict the present and future (design year 2035) performance of each alternative in terms of its effect on the level of service at the intersections. This preliminary, hypothetical analysis did not consider any other factors such as costs, complexity, or right of way. Given the known constraints of the project, some ideas were clearly over-the-top, while others were reasonable and quite practical. The alternatives he presented were:
The FM 518 Bypass is now on life support given its initial and long-term performance estimates. Contrary to its express purpose, it does nothing to relieve traffic congestion at the intersection. It's the $17 million equivalent of doing nothing. Clearly it's time to pull the plug on this idea, bury the remains, and effort to find a real solution.
The flyover from FM 270 to FM 2094 yields almost identical results to the bypass. As Mr. Polk rightly pointed out, it is simply the same solution using a different path. It will also be very expensive, require additional right of way, and take a long time to build.
Adding lanes at the intersections initially improves the congestion. The trouble is that over the long-term it will take eleven lanes between the two intersections to meet future demand. It might work but it’s unfeasible from a right of way standpoint alone, not to mention its complexity and the sheer size of the thing.
The flyover connecting FM 518 with FM 2094 shows promise in terms of relieving congestion. However, it will be very expensive, require significant additional right of way, take a long time to build, and in the end it will be a terrible eyesore. The benefits of this option are clearly overshadowed by its enormous flaws. As a potential solution it is simply unrealistic when all things are considered.
The realignment of FM 270 is effective at reducing congestion going forward. Its principal advantages are that traffic is largely unaffected during construction and it will be built at-grade. On the downside, it too will require additional right of way, existing businesses will have to be relocated, and the safety problems associated with traditional intersections will remain unchanged. Nevertheless, this option is likely one of the top three.
The single roundabout model performs as well or better than any other alternative in the short term. Its poor future performance in this preliminary analysis is questionable though as there are a number of variables which must be considered. It may be attributable to limitations in the modeling software used in this analysis or in the generic roundabout design inputs or both. Software specific to roundabout design must be used to get the most accurate results. Nevertheless, it too will require additional right of way, realignment of roads, relocation of businesses, and it will most likely have to be built under traffic. In the end, the right of way costs and realignments will likely make this alternative cost prohibitive. Mr. Polk commented that it would be too dangerous for pedestrians but this sketch hardly represents the design layout. He appreciates the potential of this alternative by noting it deserves closer look.
Mr. Polk admits he did not model the double roundabout for his presentation. That is unfortunate given the performance results for the single roundabout concept. Although it appears more complicated, in this situation a double configuration actually simplifies things. By taking full advantage of the geometry of the existing intersection layout, two smaller roundabouts increase efficiency, essentially eliminating the need for additional right of way, thus reducing costs while also improving safety. By every measure, a double roundabout will outperform all of the other alternatives.
Mark Johnson, of MTJ Engineering, is a roundabout design expert in
The double roundabout sketch is quite revealing. Whoever drew this sketch is not well versed in the "principles" of roundabout design. Just a cursory glance at this sketch and the trained eye will observe its many flaws. The geometry of the roundabouts in this sketch is contrary to the fundamentals of roundabout design. Therefore any performance estimates based on this sketch are worthless.Moreover, with most of these alternatives the need for additional right of way will be significant and expensive. Mayor Randall and Rich Oller have told me repeatedly that the city simply cannot afford to purchase the land at this location; it is simply cost prohibitive. If that is true then most of the options presented will ultimately be ruled out on that basis alone. Given that they also fail to address the core problem, the most viable candidates very quickly emerge .
At the end of the day, when all things have been properly evaluated, I predict that the double roundabout design will prevail as the best solution. Whether it will be chosen remains to be seen. Nevertheless, expert analysis will prove it to be the superior alternative in terms of its overall costs, the time it will take to build, its long-term effectiveness, and many other attractive benefits.
In summary, some key advantages of the double roundabout solution are:
The difficulty now will be persuading the public that it is the best solution. The goal of this website is to provide information in a convenient place and let each of you find your own answers. If you hate the idea now, you will probably love it six months after it's built.
The Best Alternative to the FM 518 Bypass?
September 24, 2010
At a public meeting in League City yesterday, a citizen's group, OCCAM Engineering, and city officials revealed the three most promising solutions to the traffic problems at the infamous 5-Points intersection. After three months of study, the realignment of FM 270 is their preferred choice. It is not surprising that the realignment of FM 270 is their first choice for a variety of good reasons. It is an at grade solution, its construction will be the least disruptive to existing traffic, the build time is relatively short, it is estimated to be less expensive than the other two options being considered, and it presumably solves the congestion problem.
Nevertheless, it is also clear that the roundabout idea was the victim of prejudice.
Even after last night’s meeting, it is unclear whether a single or a double roundabout configuration was evaluated. At the June meeting performance estimates for a single were presented by Mr. Polk, but not the double. Although he said they would provide performance estimates on a double roundabout concept, they have yet to be presented to the public. This is important because a single roundabout will not work here due to right of way constraints. A double configuration avoids this problem by taking advantage of the layout of the existing intersections, it will be more efficient, and it will cost significantly less than the single alternative. There are numerous other benefits.
At the meeting, Mr. Polk again made a number of remarks that reveal he is either ignorant of these benefits or has a penchant for traditional methods or he was referring to a single, large roundabout. I suspect the latter. He said that a, singular, roundabout will be big, requiring too much additional right of way, it will be unsafe for pedestrians and cyclists, it will be too disruptive, it will take a long time to build, and so on. Yet even a cursory reading of the available research literature proves such remarks to be fallacious, even downright misleading, unless of course the design under consideration is somehow flawed.
The citizen's advisory group also failed to do its homework on the subject. After the meeting, I spoke with two of its members, engineers both. After three months of "study," both of them continue to express preconceived notions about modern roundabouts that are erroneous, having no basis in fact. Their spurious conclusions regarding modern roundabouts are simply untenable yet quite revealing. Because of their bias it would impossible for them to make an objective evaluation of the modern roundabout as a potential solution to this problem.
Although I am disappointed that the roundabout idea has hardly been given a fair shake, I am glad that the bypass is now dead and buried. At the end of the day, that was really our objective. In that regard we have seemingly been successful. As they say though, “it's not over 'til it's over.”
Update: 14 March 2011
Rather than the complete realignment of FM270, the latest scheme proposed by the consultants involves building another signal controlled intersection just to the west of the intersection of FM 270 and FM518. The city has not released any of the performance numbers on this proposal yet. Why? Is it because they all know that it will never perform as well as a set of properly designed modern roundabouts. Their emphasis now is clearly on a solution the will not require the reconstruction of the existing intersections. Because of this shortsighted mindset we will get an inadequate result that will fail to solve the problem here. In fact, it could exacerbate the problem. Ten years from now we will likely be "fixing" this intersection all over again. Moreover, this scheme will require significant additional right of way. The city must acquire the Mattress Firm, a portion of the land on which the Shell station sits, plus a large portion of land and a private driveway belonging to the self-storage facility. Even with eminent domain this land will be expensive, but it is unlikely the land owner will be fairly compensated in this economy.
See the "experts" latest scheme here.
The most salient aspect of this photo is that the traffic is at a complete standstill! Notice there is only one vehicle in the two intersections. Mr. Polk argued during his presentation that the flow of traffic through the roundabouts would be too slow. Slow would be a significant improvement over the state of things today.