Monday, January 4, 2016

Cleansing Burlington's "dirty 17" high per crash locations with roundabouts

1/3/2016 Revision 1

Cleaning the “Dirty 17” Burlington, VT One-a-Year Pedestrian Injury Intersections to About One a Decade Average with Roundabouts--Opportunities and Costs


As analyzed here, cleansing 15 of the “dirty 17” Burlington intersections averaging one pedestrian injury a year occurs by converting them to roundabouts. After conversion pedestrian crashes would drop from15 pedestrian injuries a year now to one or two a year. The 90% reduction in pedestrian crashes prediction is based on single lane roundabout research and the recent tabulation of 52 years of Vermont downtown/town center roundabouts history which recorded just a single non-serious pedestrian injury. Two of the “dirty 17” intersections—one during the 2011-2014 data collected in the Walk Bike Master Plan study now under way and one in 1998—recorded a pedestrian fatality. The 2015 measure of the value of a life saved used by the Federal Highway Administration is $9.4 million. A recent value of a highway injury used in a American Automobile Association study (Cambridge Systematics) was $126,000.


The Burlington Walk Bike Master Plan identifies 17 intersections averaging one (0.9) pedestrian injuries per year for the four years 2011-2014. Just now safety performance data on of five downtown Vermont roundabouts found one pedestrian injury (not serious) over a span of 52 years of roundabout operation history through late 2015. The Burlington “dirty 17” record includes a fatal injury and at least one critically injury. Since roundabout research indicates a 90% reduction in pedestrian injuries at single lane roundabouts compared to signs and signals, “cleaning” the “dirty 17” in Burlington with single lane roundabouts reduces frequency of pedestrian crashes to one per decade and decreases injury severity as well. Of the 17 intersections all but perhaps two—requiring two lane roundabouts—are single lane roundabout candidates. Note, single lane roundabouts research conclusively finds single lane roundabouts deceasing serious and fatal car occupant injuries by 90%, and research finds single lane roundabouts for cyclists reaches towards the 90% reduction of injuries if a separate path or ramp off/on to join with pedestrians for crossings is provided.

Vermont's Montpelier Keck Circle first roundabout in the northeast (19th in the U.S.) in 1995 and Grand Union Roundabout in Manchester Center in 1997 by chance are two of the earliest downtown/town center roundabouts in the U.S. and Canada. Now along with two more roundabouts in Manchester Center and the Main Street Roundabout in Middlebury, this group of five become first to reach 52 years of service with both significant volumes of pedestrians but also an ongoing tabulation of pedestrian accident data. The Vermont downtown roundabout performance does not come as a total surprise as international research finds about a 90% reduction in pedestrian injuries at single lane roundabouts like Vermont's. Still, the Vermont downtown roundabout safety performance of one minor pedestrian injury in 52 years stands in sharp relief opposite to the Burlington “dirty 17” recording one pedestrian crash per year 2011-2014 with one fatality and at least one critical injury.

The question can be asked “what if” the pedestrian “dirty 17” intersections in Burlington were converted to a roundabout, what would be the costs? Using the rule of thumb of a 90% reduction of pedestrian injuries of roundabouts over signed or signalized intersections, the 17 injuries a year at the Burlington intersection would drop to less than two per year. The U.S. sinking from first to 19th in highway safety with over 40% of the 30,000 annual deaths prevented by reaching top nations in highway safety, this analysis is far more than a theoretical exercise. Further in the last decade as more walk and bike--”healthy transportation”--walk and bike fatalities have plateaued and even increased, and have become a higher proportion of overall highway fatalities as both modes vulnerability in crashes with vehicles is obvious and practically impossible to alter in a significant way.

The following analysis makes these assumptions;

  1. Any consideration of roundabouts at a high accident location—like the “dirty 17”-- requires a full engineering study involving an experienced roundabout designer. (Vermont remains one of the rare states where almost all the long time roundabout practitioners have either presented workshops in the State or done design work here—in some cases both.)
  2. At some point—the sooner the better--high accident intersections in Burlington will be evaluated for roundabout or other major safety upgrade, and a list of intersections will be prioritized—ditto for Chittenden County which lacks a single safe roundabout intersection on a busy public street.
  3. The cost assumptions here are that the projects will be done without use of federal funding. Costs would be roughly 75% higher with the involvement of federal funds. Where federal funds are known to be involved (Shelburne Street Roundabout and Champlain Parkway intersections) a “federal” estimate is provided.
  4. Mini-roundabouts can be built with very low costs. A high-end figure of $50,000 will be used in these estimates.
  5. All estimates are those of the author based on experience—they are “ballpark” only and can only be refined by engineering studies.
  6. All intersections would include separate walk and bike treatment or, mostly likely given constraints, off/on ramping to give a cyclist the choice of “taking the circulating travelway” or “ramping off” onto shared pedestrian space, proceeding across crosswalk(s) before “ramping on” to the street to continue on (this is the Shelbune Street Roundabout design at Shelburne/Locust/So. Willard set for construction in 2021, possibly earlier).

Estimated Total Costs for Roundabouts

The total cost estimates provided below of $39 million for 15 of the intersections exclude the possible treatments which may include a roundabout for the North Street/Murray Street node and the “area” identified in the Walk Bike Master Plan between Intervale Road and Hill Street node. The estimates for three of the intersections are for mini-roundabouts with an estimated cost of $50,000 ear. Note there are 75 signalized intersections in Burlngton and 11 conversions to roundabouts are contained in the estimates here. The North Avenue Corridor Plan includes conversion of another three signals to roundabouts. The $39 million cost for 15 roundabouts compares to the $43 million current cost estimate for the Champlain Parkway. Using a cost factor of 1.75 for federally built roundabouts (other than the three given in federal estimates, that is Pine/Locust, Pine/Lakeside and the Rotary Roundabout) the total for the 15 roundabouts is $60 million.

Roundabouts tend to score very well against alternative transportation investments in benefit cost analyses in great part because of substantial reductions in crashes (50 percent), injuries and injury severity, and low maintenance costs. In addition, roundabouts cut fuel consumption by about a third compared to signals, pollution and global warming gases by a similar amount compared to signal, sharply reduce delay for all users and provide 50 to 100% greater capacity for cars. Obviously the roundabout features a higher level of scenic quality.

Outline of Possible Roundabout Treatments for Burlington's 17 High Pedestrian Injury intersections

Note again the following 17 intersections evaluation proceeds without consideration to priority or connection with other planned City intersections except for the Parkway intersections of Pine/Locust, Pine/Lakeside and the “Shelburne Street Roundabout” (Shelburne/Locust/South Willard)--all currently scheduled for funding in committed projects and therefore are considered fully funded.
  1. North Winooski/South Winooski (North Winooski/Pearl), South Winooski/Cherry, South Winooski/Bank, South Winooski College, and South Winooski/Main)
These five intersections represent the only “corridor” where all show up on the high pedestrian crash list. This corridor and Battery Street are the only two-way north/south through streets serving the Marketplace. The Burlington Town Center plan to connect Pine Street again from Pearl Street southward through the Town Center would move a significant amount of vehicle traffic off South Winooski (and some off Battery Streets). Roundabout treatments need to be part of a corridor (Pearl to Main) approach of five roundabouts developed together as a package over a period of time as each relates directly to the performance of adjacent roundabouts. The improved connectivity from a Pine Street re-connection would result in traffic reduction on South Winooski would perhaps change some of the challenges for roundabouts along South Winooski intersections.

North Winooski/Pearl

Treatment: This intersection presents the most difficult challenge along South Winooski. Only the southwest quadrant presents the possibility of a roundabout. Roundabouts do can be off center in an intersection. Still a major traffic calming treatment is required to reduce pressure on the Church/Pearl mid-block crossing. Cost: $3 million (if feasible).
South Winooski/Cherry

Treatment: A single lane roundabout can be fashioned with use of institutional right-of-way to the east and possibility a slight amount from the Rite Aid site (Rite Aide gets the benefit of a possible direct entry onto the roundabout). Also the resolution of revamping North Winooski/Pearl and South Winooski/Bank ties directly to design for this intersection. Estimated cost: $3 million

South Winooski/Bank Street

Treatment: Utilizing the likely moving or closure of both gas stations at the west corners of the intersections as high level economic value uses take over these two sites, space can be reserved allowing an easy installation of a one lane roundabout which would also benefit the developments occupying the space of the former gas stations. Estimated cost: $3 million

South Winooski/College
Treatment: Right-of-way restrictions from three of four corner buildings (also narrowest width between east and west buildings on South Winooski between Pearl and Main) only allow consideration of a mini-roundabout. Again, a mini-roundabout needs to be part of an overall set of intersection treatments from Pearl to Main. Since even with current traffic levels a “road diet” has been suggested, such a change would augur well for a mini-roundabout feasibility. Estimated cost: $0.5 million.

South Winooski/Main
Treatment: Likely the only intersection requiring a two-lane roundabout with pedestrian actuated signals designed primarily for those with severe visual disability. Also the most expensive roundabout. Estimated cost: $6.0 million

2. Shelburne Street “Rotary” at Locust/South Willard

Treatment: “Shelburne Street Roundabout”, single lane, 100% federally funded safety project scheduled to be completed sometime during 2018-2021. Chittenden County Regional Planning Commission (CCRPC) “Transportation Improvement Program FY 2014-2017.” Total Estimated cost: $2.9 million (100% of funding from federal sources already allocated)

      1. Archibald/Intervale Ave
Treatment: This four-way stop intersection clearly lends itself to a mini-roundabout treatment. The skewed character of this intersection does present some design challenges. Estimated cost: $50,000

      1. Riverside—Intervale Rd to Hillside Ave
Treatment: This “area” with four pedestrian injuries may be better served by traffic calming and other related treatments. A serious bike injury—typical of multi-use paths at signals—occurred at the Riverside/Intervale Rd intersection as a cyclist crashed into a car with a green light entering Intervale Rd from Riverside—establishing a barrier/buffer to force cyclists to come to a stop or a roundabout for the intersection might be possible. Treatments to be determined after an engineering study. Estimated cost: No estimate at this time.
5. North Street at Murray
Treatment: The Walk Bike Master Plan suggestion for this “area” is a “shared space” concept. Such a design could very well include a circular paving area at Murray where vehicles would enter/exit Murray in a “roundabout manner.” This approach has been used in European applications. Estimated cost: No regular roundabout to be used.

6. North Winooski/North
Treatment: This fully signalized intersection with pedestrian actuation can be covered to a mini-roundabout. With four commercial/retail buildings on each corner the intersection does generate a significant amount of foot traffic. Estimated cost: $50,000

7. Loomis/North Prospect
Treatment: This two-way stop control intersection can be converted into a mini-roundabout which will traffic calm Prospect, a busy minor arterial street. Estimated cost: $50,000
  1. Main/St. Paul
Treatment: This intersection adjacent to City Hall Park was the site of a high speed chase involving police and the miscreant driver whose vehicle T-boned a vehicle driven by Kaye Borneman, a employee. “Normal” roundabouts with central islands virtually eliminate the T-bone crash—and roundabouts when installed in downtowns and town centers also make high speed chases difficult and interception by law enforcement easy at the nearest roundabout. With the availability of some public land a normal roundabout may be feasible at this intersection or if not feasible a mini-roundabout is indicated. Estimated cost: $3 million

9. Pine/Lakeside Ave
Treatment: This signal intersection along the Parkway route will experience considerable increase in traffic volume with the Parkway completed as now designed. With a coffee shop, Department of Public Works main office facility and a gas/convenience store bordering, some design challenges exist. But relatively open area at the gas/convenience store site—perhaps it will have direct roundabout entry--makes it very likely a workable roundabout design is feasible. While the City is spending about $420,000 of local funds currently for a signal upgrade, the City costs for a roundabout as part of the Parkway would be 2% of an estimated total cost of $5 million as a federally funded project or $100,000.
Estimated cost: $5 million
10. Colchester/Barrett
Treatment: This intersection is part of a complex of streets requiring a larger design solution—very likely at least two single lane roundabouts. Colchester/Barrett and Colchester/Riverside Ave intersections are closely related, and Riverside also has a spur easterly enabling vehicles to cross between it and Barrett. Overall the overhaul of these two intersections along with Mill Street, a T intersection between the Colchester/Riverside/Barrett connections to the north and a few feet from the bridge to Winooski, may lead to making Mill Street one-way westerly with an outlet onto Barrett. Roundabouts would enable such a circulation solution. With likely retaining walls and other structural needs to accommodate a satisfactory engineering solution, an estimated cost may well climb to about $8 million. For purposes here, $4 million will be allocated as the cost responsibility for Colchester/Barrett. Estimated cost: $4 million

11. Colchester/East Ave
Treatment: Colchester/East Ave presents perhaps the easiest normal roundabout opportunity with publicly owned land on three quadrants and no right-of-way constrictions on on the west side of Colchester Ave.
Estimated cost: $2 million
12. Pine/Locust
Treatment: A critical injury at this intersection occurred a few months after installing a Rectangular Rapid Flashing Beacon (RRFB) for crossing Pine Street only. A single lane roundabout is feasible at this intersection because of the availability of right-of-way on the west side of Pine from property owned by BED. This intersection would likely be upgraded as part do a “corridor of roundabouts” including Pine/Howard and Pine/Lakeside intersections converted to roundabouts (up to 10 or more roundabouts conceivable along the Parkway). The cost of this intersection for the City will be estimated at 2% of $3 million (federal project cost) as part of the Parkway project, or $60,000. Estimated cost: $3 million

13. Shelburne/Home
Treatment: This intersection definitely requires a two-lane roundabout and along with South Winooski/Main (possibly) represent the only two multi-lane roundabouts among the 17 intersections. Still, Shelburne/Home will experience some decline with the opening of part or all of the Parkway, conceivably decreasing the traffic to the point a single lane roundabout suffices. Linda Ente during a trip work at Price Chopper was killed on the crosswalk at this intersection in 1998. Estimated cost: $4 million

Tony Redington

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