Stop extra-heavy vehicles from ruining streets and bridges

Click here for a PDF of the Nov. 9, 2022 SDOT memo to the Seattle City Council. A fully digital version available at the City web site. As the Mayor and City Council agreed in the 2022 budget legislation to require of SDOT, this memo classifies the types of over-weight vehicles, analyzes their impacts on Seattle arterials, non-arterials, bridges, sidewalks, and areaways, presents options to reduce the ongoing damage these overweight vehicles are doing. However, the SDOT report does not comply with the legislative requirement that it estimate the “cost to repair” this damage.

Click here for Statement of Legislative Intent SDOT-009-A-002, “Request that SDOT report on the impact of over-weight vehicles.” This “SLI” consists of a detailed request for SDOT to report to the City Council. It is an official part of the City of Seattle 2022 Adopted Budget, page 879. [SDOT missed the official Sept. 1, 2022 deadline for submitting the report to the City Council, and the word now (10-15-22) is that the report is still stalled in the Mayor’s office.]

Click here for a May 21, 2007 memo by Seattle Department of Transportation civil engineers, “Metro Bus Damage on Pavements and Structures,” documenting that much of the ongoing damage to Seattle roads and bridges is by extra-heavy public transit buses.

Click here for a proposal submitted 5/15/21 to the City of Seattle for amendment of the Comprehensive Plan to include a policy discouraging damage to streets and bridges by extra-heavy vehicles.

HOW STREETS AND BRIDGES ARE BEING DAMAGED BY EXTRA-HEAVY VEHICLES, AND WHAT TO DO ABOUT IT

Street and bridge damage increases exponentially with weight. That is the finding of generations of engineering studies from federal, state, and local transportation agencies and by university researchers. At heavy vehicle weights, just a slight further increase in weight causes a disproportionately higher amount of damage. For this reason, the long-term survival of our streets and bridges depends critically on reducing and preferably eliminating the loads imposed by extra-heavy vehicles.

Unfortunately, Seattle’s streets and bridges are rapidly deteriorating largely from the impact of extra-heavy vehicles, which cause the overwhelming majority of the damage. And while some of these vehicles are illegally overweight, most of the damage is from vehicles that state and federal laws allow to be heavier than is allowed for other vehicles of that weight.

Washington state and the City of Seattle (like most other states and localities) are freely allowing extra-heavy vehicles on streets and bridges at unacceptably damaging levels. The result is to shorten the safe and useful life of streets and bridges, just when there is fierce competition for other uses of the funds that are needed for repair or replacement. But even as the gap widens between the deterioration of Seattle’s streets and bridges as the funds needed to fix them, the City government is not taking the more affordable step of stopping the damage, especially its own affirmative and passive roles in the damage.

In Washington, one state law (RCW 46.44.041) establishes vehicle weight limits, but other state laws make many exceptions. Examples: Under RCW 46.44.0941, municipal garbage and recycling contractors enjoy a one-year renewable state permit allowing their trucks to be heavier than private trucks. RCW 46.44.190(5) allows any municipal fire truck to receive a permit for additional weight, and RCW 46.44.190(7) exempts fire trucks in operation before June 13, 2002 from any weight limit. RCW 46.44.042 allows additional weight for certain fire trucks and concrete trucks. In all of these cases, the city of Seattle and other localities allow their own and contractors’ vehicles to exploit these opportunities for extra-heavy loads, rather than insisting that they keep to truck weights that will not unreasonably damage local streets and bridges.

Vactor trucks. The City’s and County’s drain and sewer-cleaning “vactor” trucks breach the legal weight limit when they are only half full. Yet it is common for City and County drivers to operate these vactor trucks well over half full, at weights that are illegal and are causing serious damage to City streets and bridges.

Fire trucks. Under state law, local fire departments are eligible for (but not required to make use of) the following weight exemptions: RCW 46.44.190(7) allows fire trucks to exceed state weight limits if they were in operation before June 13, 2002. RCW 46.44.190(5) allows more recently acquired fire trucks to receive permits for additional weight. The City of Seattle appears to be using these exemptions without any consideration of the damage that it is imposing on its streets and bridges.

No one questions that, in actual emergencies, some street and bridge damage from the use of extra-heavy fire trucks is acceptable. But protocols are needed for when extra-heavy fire trucks can be used in non-emergency situations, especially when lighter weight vehicles are available. Also, it is important in future purchasing that the City fully explore the choice of fire trucks that are not so heavy that their use requires use of the legislative exemption allowing extra-heavy weights that do unnecessary damage to Seattle’s own streets and bridges.

Solid waste trucks. Under state law, garbage and recycling trucks are allowed by RCW 46.44.0941(3) to be issued a one-year renewable state permit to operate somewhat heavier than otherwise allowed for other trucks (except for the abovementioned unlimited regulation of the weight of fire trucks). Unfortunately, the City of Seattle freely allows its own contractors’ garbage and recycling waste trucks to make use of this state exemption to operate at weights that are known to cause serious street and bridge damage.

Illegal truck weights are also reached by the City’s solid waste contractors, as SDOT and SPU found two decades ago when the City Council mandated surprise weight checks, showing that many solid waste trucks were heavier even than the extra weight allowed by the state permit just mentioned.

The Washington State Department of Transportation has found that because extra-heavy solid waste trucks are everywhere, they damage more streets and bridges than any other vehicle on the road. WSDOT does not allow solid waste vehicles on Interstate highways if they are so When solid waste trucks would need to use the special exemption for more weight. In contrast, Seattle neither prohibits nor disincentivizes its own solid waste contractors from using the special exemption for more weight.

The City of Seattle must cease its generations of abdication of responsibility, and must place a weight limit on its solid waste contractors. The City should either require its contractors not to operate at a weight more than the normal state limits (that is, the contractors would not use the state’s exemption for overweight solid waste trucks), or the City should provide them financial incentives not to make use of this exemption.

In 2001, after the author suggested this policy, Seattle Public Utilities’ Solid Waste Contract Manager stated:

“Your suggestion on contract incentives to use smaller trucks is an excellent one. Our current contracts did not contain this incentive in the Request for Proposals and there is no contract language covering this issue. However, we can and will include this type of incentive in any new contract offerings. We could also ask for differing proposals and prices. One proposal and price would require that the contractors only use collection vehicles that do not exceed a certain weight. An alternate proposal could encourage the incentive of “bonus” payments if the use of large overweight trucks were kept to a minimum. Asking for two proposals and prices, one of which would be for light trucks, would enable the City to see the different collections prices and compare it to the cost of road deterioration/maintenance. Other advantages of using lighter, smaller trucks are that there should be fewer incidences of property damage and fewer trucks in a collection area (as a smaller truck can serve the narrow alleys and streets). It is unfortunate that we did not include this type of language in our current contracts. This issue was just not on our radar screen as we were preparing the RFP.”

This SPU official retired, and his successors have not followed up. The many requests for proposals and contracts that SPU has issued have contained none of the hoped-for improvements, allowing unnecessary damage to the City’s streets and bridges by its own solid waste contractors.

Public transit buses. According to a May 21, 2007 SDOT memo, the most expensive damage to Seattle streets and bridges is by public transit buses. (This study does not appear ever to have been presented to the City Council or Mayor, but we provide it to City officials and to the public now at http://public-interest.us/SDOTmemo2007). The memo states (p. 6) that these buses “constitute the majority of heavy vehicle traffic on many of Seattle’s streets”, and that the damage is worsened by constant stopping and starting typical of transit bus operation. This finding is echoed in other cities. Austin, Texas, for example, found that 70 to 90 percent of its arterial street damage was caused by transit buses.

To make matters worse, a federal law (adopted without opposition from the City of Seattle, the state government, and many other states and localities) that requires states and localities to allow public transit buses on their streets and bridges no matter how heavy and damaging these buses are. And although this federal law does not require the purchase of extra-heavy transit buses, local agencies like King County Metro, Sound Transit, and Community Transit have been purchasing the extra-heavy buses that consequently are damaging streets and bridges throughout the region. Seattle City government has not sought to change the federal law nor to persuade these local agencies to purchase transit buses with weights that will not unreasonably damage the City’s streets and bridges.

The evidence of the street and bridge damage that is being done by extra-heavy transit buses is all around us. The streets that the buses use have cracks in the concrete pavement, and asphalt pavement that is curled up as if by a plow. The 2007 SDOT memo warns (p. 6) that “To continue to deploy heavier buses will result in a significant acceleration in the deterioration rate on bridges.”

According to the 2007 SDOT memo, in 1993 none of Metro’s buses exceeded the recommended single-axle maximum of 24,000 pounds, but by the date that the memo was written, 47 percent of Metro’s fleet exceeded that weight. Between 1993 and 2007, “the average pavement damage factor per bus is estimated to have increased by around 30%.”

The “hybrid electric” buses now popular are especially heavy because they are both diesel and battery/electric motor powered–and thus even when empty, are the heaviest vehicles on the road, with every trip doing unnecessary damage to Seattle’s streets and bridges. Even the electric trolley buses, once well within the weight limits that would apply if buses were not exempt, are creeping up in weight because of the addition of batteries for off-wire use.

West Seattle is a case study in the consequences of neglecting the street and bridge damage from extra-heavy vehicles. SDOT has acknowledged that heavy transit buses were among the contributors to cracking, near collapse, and emergency closure of the West Seattle high bridge and the ongoing expensive repairs that were not expected to be needed so soon after its construction. After years of repairs, the bridge reopened in September 2022. But because the City of Seattle has not yet addressed the problem of over-weight vehicles, it is quite possible that the newly repaired West Seattle Bridge will again suffer unnecessary damage and a shorter life.

Ironically, the West Seattle high bridge is named after Jeannette Williams, who as Transportation Committee chair and City Council President in the late 1980s and early 1990s mobilized the Council to successfully persuade Metro not to buy extra-heavy transit buses. This was the only time in Seattle history that the Council took any action to protect our streets and bridges from damage by extra-heavy transit buses.

Communities in West Seattle have organized against street damage caused by extra-heavy transit buses. For background, click here [link not yet added]. For a March 20, 2015 letter to SDOT from the Westwood-Roxhill-Arbor Heights Community Council, click here [link not yet added]. For a March 8, 2016 article in the West Seattle Blog about a public meeting on the subject; click here [link not yet added]. And for a Jan. 3, 2020 article in Westside Seattle reporting that that the years of organizing have produced little progress on the matter, click here [link not yet added].

Conclusion. It is far more cost-effective to avoid or reduce street and bridge damage before it happens than afterwards to repair the damage or to entirely replace the street or bridge—if these larger funds are even available when needed. By avoiding unnecessary damage to streets and bridges, funds that would otherwise go for their repair or replacement will be available for other transportation projects, for social needs, or to stay in the taxpayers’ pockets. Bridges will be less likely to fall or need to be replaced; and streets will be safer to navigate for motor vehicles, bicycles, and pedestrians.

Even as the City spends huge amounts to repair or replace the results of previous damage, arterial streets continue to be damaged by extra-heavy vehicles, especially public transit buses. Non-arterial streets, which are two-thirds of Seattle’s lane-miles, receive very few maintenance dollars, even as they are being further degraded by extra-heavy vehicles, with the most damage being done by solid waste vehicles that are under City contract that the City could use, if it chose to reduce or eliminate the damage.

Reducing the disproportionately high level of street and bridge damage from extra-heavy vehicles would protect Seattle’s infrastructure and would free up taxpayer funds for other transportation projects and for social needs. If we find ourselves in a hole, the first thing is to stop digging. (Or, to extend the metaphor, we could continue to bury our heads in the sand.)

It is to be hoped that SDOT has considered the above information and analysis in preparing the report to the City Council on the impact of over-weight vehicles on Seattle’s street and bridges that the City Council requested in Statement of Legislative Intent SDOT-009-A-001. This “SLI” is an official part of the City of Seattle 2022 Adopted Budget, page 879.

Of concern is that SDOT missed the official Sept. 1, 2022 deadline for submitting the requested report to the City Council, which did not receive the report until November 9, 2022, possibly too late to influence the 2023-24 budget. It is essential for the Mayor and City Council to receive all the facts and analysis prepared by SDOT’s engineers, uncensored by political pressures, for how to most effectively and economically protect the City’s streets and bridges for current and future use.

Chris Leman
cleman@oo.net