APPENDIX F

Technical Memorandum: Summary of State Agency Survey Results

Executive Summary

BrTS pose a significant threat to public safety, resulting in damage to vehicles and infrastructures, injuries/fatalities, and costly delays for highway users. Meanwhile, the lack of comprehensive information on the number, location, and severity of BrTS impedes the identification of at-risk structures and the implementation of cost-effective countermeasures. In response to this challenge, the project team collected BrTS data from traffic safety analysts/traffic engineers at state DOTs as well as developed a comprehensive survey to gain feedback from state agencies on the prevalence of BrTS and the effectiveness of current prevention measures.

The survey consists of 30 questions divided into five sections. It was distributed through the AASHTO COBS and the ATSIP. Thirty-five respondents were received, 25 of which were considered valid. The majority of respondents were bridge engineers and inspectors and do not belong to the ATSIP members that responded to our BrTS data request.

In terms of BrTS data management, nine states (Delaware, Indiana, Michigan, New York, Nebraska, Pennsylvania, Rhode Island, South Dakota, and Texas) claimed to have established a stand-alone BrTS database. Eight states (Delaware, Michigan, New York, Nebraska, Pennsylvania, Texas, Kentucky, and Wisconsin) indicated they have developed a risk assessment method to identify risky bridges/tunnels. While most of the responding agencies (13) do not track repair costs for BrTS damages as part of their data, seven states (California, Delaware, Indiana, Minnesota, New York, Pennsylvania, and South Dakota) do retain this information. It would be good practice to establish a centralized data inventory system that would house data on structure, crash, and cost for consistent BrTS information management. AASHTOWare™ Bridge Management (BrM) software has been cited repeatedly in the survey responses, so that might be one option for agencies to record and store bridge damage information. Indiana’s use of the DamageWise program for tracking damage to state property is another example of a good practice.

Some important facts have been observed with regard to BrTS statistics: 1) most respondents (18 or 72%) agreed that BrTS are underreported; 2) ‘bridge upper structure’ has the highest estimated percentage of collisions by OHVs, followed by ‘bridge railing or parapet’ in cases of on-bridge collisions; 3) it is a consensus from the respondents that strikes are mainly due to driver error (e.g., improper measure/operation of cargo height and unpermitted loads; 4) the most common practice (11 states) is to post a sign for 3" less than the actual measured clearance; 5) zero states provide lane-by-lane vertical clearance information as a resource to motor carriers and drivers; and 6) 11 (74%) states require a routing analysis prior to granting OSOW permits. States frequently cited ProMiles and Bently Superload as useful automated permitting/routing systems, which aligns with the literature findings. States that experience a high number of BrTS crashes often face difficulties accessing BrTS statistics and have not developed risk assessment methods to identify bridges that are at a high risk of being struck by motor vehicles.

The survey included two questions about the current practices and future plans for BrTS detection and mitigation countermeasures by transportation agencies. Rankings were analyzed based on popularity and are provided in the summary. More than 50% of state DOTs indicated they’re using the following measures

to prevent/mitigate BrTS: 1) Online Maps (e.g., up-to-date height or size restriction, interactive maps through a DOT website such as 511); 2) Static Warning Signage; 3) Bridge Markings; 4) Route Surveys; 5) Increased Structure Vertical Clearance; 6) Axle Load Restrictions; and 7) VMS. The only measure for detecting BrTS that is being utilized by more than 50% of respondents is “Beacons, Flashing Beacons, or Lights”. In addition, state agencies use various levels and scales of involvement to communicate with the trucking industry on BrTS issues, including regional/national meetings, partnerships with the trucking industry through advisory committees, regular meetings, and data sharing, in-house systems, online resources, and CDL training.

When asked about a state’s response to a frequently struck bridge/tunnel, as the answers are: 1) additional/advanced signage/control devices/overheight warning devices; 2) replacement priority, earlier rehab/replacement, or given additional strength in the repair; 3) lowering the pavement or increase vertical clearance; 4) driver awareness education; and 5) roadway geometry adjustment.

Introduction

BrTS inflict serious damage to vehicles and highway bridges/tunnels, cause injuries and fatalities, impose costly delays on highway users, and require expensive responses from bridge/tunnel owners, managers, and public safety agencies. A lack of comprehensive information on the number, location, and severity of BrTS hinders efforts to identify at-risk structures and implement cost-effective countermeasures. In response to this challenge, the project team collected BrTS data from traffic safety analysts/traffic engineers at state DOTs as well as developed a comprehensive survey to gain feedback from state agencies on the prevalence of BrTS and the effectiveness of current prevention measures.

It is also important to collect data regarding driver behavior and characteristics, driver education programs, training and safety awareness, corporate safety culture, state agencies’ policies and procedures for designing and operating bridges and tunnels, as well as permitting, escorting, and enforcing oversize/overweight (OS/OW) vehicles, etc. Thus, this survey takes into account NCHRP 08-139 Project Guide for Preventing and Mitigating the Risk of Bridge and Tunnel Strikes by Motor Vehicles to collect additional information. It is essential to use data to assess the impact and risk of BrTS and establish a framework for identifying and evaluating effective preventive measures. The purpose of the survey was to gather feedback from various state agencies that would inform the development of a national clearinghouse for collecting and analyzing BrTS data.

The survey is comprised of five sections. The first section pertains to the survey participants and their affiliations. The subsequent sections contain a total of 30 questions that cover different aspects of BrTS. Specifically, the second section focuses on general BrTS information, including the quantity of bridges and tunnels under maintenance, the frequency of bridge and tunnel strikes, the types of damages sustained, the maintenance records kept, the costs of repairs, and so forth. The third section queries participants about their respective practices of detecting, reporting, preventing, and mitigating BrTS. The fourth section deals with the regulations, practices, and guidelines implemented by the state regarding overheight vehicles. Lastly, the fifth section invites participants to provide any additional comments they have regarding BrTS.

The Qualtrics-based survey was distributed to the ATSIP with the assistance of Vanasse Hangen Brustlin, Inc. (VHB), as well as to the AASHTO COBS with the assistance of the project manager, Mr. Abu-Hawash.. Twenty-five of the 35 surveys received were considered valid, as they contained answers to at least one of the main questions.

Basic Information about Survey Participants

The survey was distributed to all states in the US, targeting state DOTs. The first section collects basic information about survey participants, including their geographic information and their relationships to BrTS. Twenty-five valid responses from 20 DOTs, one state agency other than a DOT, and one local agency were received. Figure F1 displays in blue the states that participated. Three states (CA, DE, and IN) provided multiple responses, either from different respondents within the same agency or from different agencies. One individual affiliated with the Indiana Criminal Justice Institute responded to the survey because of their responsibility for managing traffic safety data. Additionally, one response is from the Guam Department of Public Works.

Most survey respondents are bridge engineers and bridge inspectors who are not included in the group from ATSIP that responded to the BrTS data request. Ten states responded to both the BrTS data request and state agency survey, as shown in Table F1.

Table F1. States Responded to BrTS Data Request and the Survey.

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¹⁶ In September 2022, the project team coordinated with the Association of Transportation Safety Information Professionals (ATSIP) to send two data requests to its member agencies: 1) crash data on bridge and tunnel hits and 2) roadway, traffic volume, and structures data. By the end of October 2022, over twenty (20) state agencies responded positively to our data request.

General BrTS Questions

First, the agencies were asked about the number of bridges/tunnels they regularly maintain and update in their bridge/tunnel inventory. Table F2 provides the summary of all 25 responses. Statistics from both the 2022 NBI and the 2022 NTI are also included in the table for comparison. Most states provide similar numbers, although discrepancies can be observed for California, Delaware, and Indiana. The reason for these differences might be the fact that some respondents belong to different agencies, or different units/regions within the same agency. For example, for “California DOT response 1”, the person is responsible for toll bridge inspections, and for “California DOT response 2”, the person is responsible for SM&I of the North region, while the “California DOT response 2” respondent is a supervising bridge engineer responsible for all bridges. The discrepancies suggest that some states do not have a centralized bridge/tunnel inventory that can be accessed by all stakeholders.

an estimate of the number of BrTS. Table F3 shows the number of bridge strikes (2019-21). Fourteen out of 25 (56%) of the respondents provided bridge strike statistics, 6 (24%) chose “I do not have any bridge strike statistics” and 5 (20%) did not answer the question. Indiana and Delaware each included two responses. In Delaware, both answers are the same, while in Indiana, answers are very different with the two respondents being from two different agencies. When crash statistics were connected with the number of bridges, it was observed that Texas has a comparatively lower number of bridge strikes despite having the highest number of bridges among all states that responded.

Table F4 shows the data regarding tunnel strikes: 8 respondents (32%) provided tunnel strike data; 14 (56%) selected “I do not have any tunnel strike statistics”, and the rest (12%) did not answer the question. The data shows that tunnel crashes are uncommon, and this is to be expected considering the small number of tunnels in the surveyed states. Remarkably, Rhode Island reported the highest number of tunnel collisions among all respondents, despite having only one tunnel.

Table F5 shows how BrTS data are obtained for the responding states. Out of the 25 respondents, 10 (40%) responded that the state obtained data from a stand-alone database. Of the remaining respondents, 10 (40%) chose the option “Difficult to find from crash data or other sources”, 3 (12%) chose “limited or no knowledge”, and 2 (8%) chose the option “Easily identified from crash data or other sources”.

Table F6 shows additional comments on the stand-alone database used by the agencies. The project team received data for just three of the respondents that claimed to have a stand-alone BrTS database for their state (Michigan, Pennsylvania, and Texas); however, the data retrieved from those states came from the state-maintained crash databases, and not from stand-alone BrTS databases. This reaffirms that different practices may exist within the same agency when it comes to housing BrTS data, especially when you consider that the people who responded to the data request and the survey are from different units of the same agencies.

The AASHTOWare™ Bridge Management (BrM) software was mentioned three times, which might indicate a common practice by agencies to record and store bridge damage information. The respondent from the Indiana DOT referred to the DamageWise program which helps record damages to property by motor vehicle crashes, as well as the associated costs. This process could be considered for further investigation as a possible best practice that can be adopted by other agencies.

Table F6. Comments on the Stand-alone Database Used by Agencies for BrTS.

The respondents were also asked to estimate the percentage of non-reported BrTS incidents. Figure F2 shows a histogram of their responses in different percentage categories. The most prevalent answer was that 10-49% of BrTS crashes are underreported. “I do not know” was the next most frequent answer. Despite the large disparity, 18 out of 25 (72%) agreed that there is some level of underreporting.

State agencies are notified of BrTS incidents through a variety of methods. Respondents were asked to choose the options their state uses and estimate the percentage of BrTS that are reported using each method. Figure F3 shows the large disparities of how a BrTS was notified or reported among agencies, even within the same agency such as California and Delaware. This might cause concern about their notification methods, but it could also be explained by procedural differences in discrete operational areas (e.g., tollways versus all other roadways). Table F7 provides further details of “other ways” by agencies. The most common practices beyond the provided options are “TMC” (e.g., live camera) and inspection/maintenance personnel (e.g., routine or special inspections/maintenance). Respondents from New York and Wyoming said social media has been used to gain crowdsourced data, and Delaware indicated they receive crash reports from citizens/legislators via social media.

Table F7. Other Methods to Notify BrTS Used by Agencies.

Respondents were asked to provide information on which specific parts/components of a bridge are hit during a BrTS. They were asked to give estimates for each option so that the total of all options equaled 100%. Figure F4 shows the percentage breakdown of bridge components struck due to BrTS. “Under bridge upper structure” has the highest mean value of percentage estimation for collision by OHVs, followed by “On bridge railing or parapet”.

Respondents were then asked to choose damage types based on their observations and to estimate the percentage amount for each option. As shown in Figure F5, it is evident that “mostly scrapes” is the most

common damage type, followed by “structural damage”, “partial damage”, and finally, “catastrophic damage”. However, it is apparent that several states still consider structural damage to be a significant issue.

Table F8 shows the responses from agency officials on whether their agencies record repair costs for BrTS damage caused by motor vehicle strikes. It is evident that most agencies (13 out of 19, or 68%) do not keep such information. Even if an agency does keep repair cost records, the information can be difficult to find.

Several agencies provided additional comments on this question, which can be seen in Table F9. Several states estimated that the bridge owner bears the largest portion of the cost because, in most cases of BrTS (mostly the non-reportable cases), the party that caused the damage cannot be identified. The additional comments also reflect the previous finding that routine inspection/maintenance might help identify non-reported BrTS.

Table F9. Additional Comments on Costs Resulting From BrTS.

Figure F7 shows the percentage breakdown of traffic impacts resulting from BrTS. One to 6 hours of impact was the most frequent response with a mean value of 28.84%. The next most frequent response was none, with a mean value of 22.28%. The rest of the categories are ranked in order ‘>3days’ (5.56%), ‘7-24 hours’ (4.80%), and ‘1-3 days’ (2.52%). Table 10 shows any additional comments on this question, which detail how the options and percentages were chosen or calculated.

Table F10: Additional Comments on the Percentage of Traffic Impacts Resulting from BrTS.

Bridge Strike Detection and Mitigation

Respondents were asked via three questions to share information regarding bridge strike detection and mitigation. Table F11 shows the percentage of responses for each option or cause as the primary reason of BrTS. Most agencies consider strikes to be caused by the driver, such as by the driver’s lack of knowledge of the height of their cargo, improperly loaded equipment, improper measurements of the height of the cargo, an unpermitted OHV, load shifts or equipment failures, etc. At the other end of the spectrum, causes that are considered to be less likely are mostly related to the mismanagement or ignorance of responsible authorities.

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¹⁷ The “Clankers” consist of orange rubber buoys that hang from chains from mast arm type of traffic signal support structure. See article: https://www.delawarepublic.org/delaware-headlines/2022-07-14/deldot-installs-new-system-to-reduce-crashes-oncasho-mill-road

Table F12. Measures Used Now vs. Planned in Future to Prevent and Mitigate BrTS.

Similarly, respondents were asked to indicate measures for BrTS detection. Table F13 shows the 15 survey responses, for which no additional responses were received.

Table F13. Measures Used Now vs. Planned to Detect BrTS.

Over-height Regulations, Practices, and Guidelines

Respondents were asked several questions related to OHV regulations, practices, and guidelines in their state. The first question about the state’s statutory minimum vertical clearance for bridges/tunnels shows that states have quite different practices. Though 14′6′′ and 16′6′′ are mentioned more frequently, it appears as though they are used in certain situations, such as for different road functionalities and different structure designs. Inconsistencies were observed for Indiana and Delaware. Table 14 shows the detailed responses from all respondents.

Regarding the statutory maximum height limit for vehicles and cargo, 13′6″ and 14′ are the most common practices according to the results (Figure F8 below).

Responses from South Carolina and Wisconsin show that they don’t have a statutory maximum height limit for vehicles and cargo. However, in Wisconsin any vehicle over 13′-6″ requires a permit. Zero inconsistencies were observed among the responses from California, Delaware, and Indiana. Table F15 shows the detailed responses from all respondents.

Table F15. Responses to Each State’s Statutory Maximum Height Limit for Vehicles/Cargo.

In terms of state’s policy on posting bridge and tunnel clearances, it can be seen from Figure F9 that the most common practice is to sign for 3" less than the actual measured clearance for the posted clearance sign. Inconsistent answers are observed from Delaware and California according to Table F16 below.

Table F17. Summary of State’s Policy on Posting Signs for Bridge/Tunnel Underclearance.

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¹⁸ “03 Where the clearance is less than the legal maximum vehicle height, the W12-2 sign with a supplemental distance plaque should be placed at the nearest intersecting road or wide point in the road at which a vehicle can detour or turn around.”

¹⁹ The placement of a bridge clearance sign can be found in MDOT Traffic and Safety Sign Design, Placement, and Application Guidelines, Table 21: “Bridge connection with left edge of sign over left edge of right lane. - If a guide sign is located on the bridge over the right lane, the Bridge Clearance Sign should be located left of the guide sign; The Bridge Clearance Sign should not be placed over a lane line; When 2 or more bridges are spaced at intervals of 300’ or less, place the Bridge Clearance Sign only on the first structure. - Use the lowest clearance to determine the dimension shown on the sign.”

The majority of respondents indicated that state DOTs issue Oversize/Overweight (OS/OW) vehicle permits, at least for state highways. Indiana was the exception, where the Indiana Department of Revenue is in charge. Four states, Michigan, Minnesota, New York, and Wyoming denoted that local agencies (city or county) are responsible for issuing OS/OW vehicle permits for local routes. Table F18 shows the responses to the question about OS/OW issuing authority.

Table F18. Summary of Responses about the Permit Issuing Authority/Agency of a State.

Table F19 shows the summary of responses regarding routing systems used by a state for permitted overheight vehicles. According to the responses, most (14) chose the option “Carrier may propose route and submit to state for approval” which is the highest category. Twelve respondents chose the option “State determines specific route for permitted vehicles”. The respondent from Wisconsin selected “Other”, and provides additional information regarding how that state system operates²⁰.

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²⁰ The state system performs for single-trip permits exceeding 16′ inches. Between 13′-6″ and 16′, multi-trip permits are allowed, and the carrier is required to review their route via an online list with all bridges having clearances below 16′-3″.

Table F22. Comments on Other Methods Used by Agencies to Route Trucks/OHVs.

When asked where a driver finds roadway restriction information along the route if a permit is not required, seven out of 16 respondents selected “Other” which indicates the challenges for a driver to easily find roadway restrictions information. One respondent said no source within the state provides such information. The survey results show that no agency provides lane-by-lane vertical clearance information, or at least such information is not publicly available. Although the literature review points out that the Indiana DOT collects, maintains, and reports lane-by-lane clearance measurements and other data on over 2,100 bridges throughout the state²¹, neither respondent from Indiana selected the “lane-by-lane vertical clearance” option. Table F23 presents the summary of responses, with additional comments in Table 24 if “Other” was selected. Most “Other” information includes additional comments regarding the state’s in-house online maps. Michigan and Texas noted that it does keep vertical clearance information for state-owned structures with overhead clearances less than 14 inches.

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²¹ INDOT Statewide Bridge Clearance Interactive Map https://www.arcgis.com/home/webmap/viewer.html?url=https%3A%2F%2Fmaps.indot.in.gov%2Farcgisro%2Frest%2Fservices%2FDOT%2FINDOT_RH_BRIDGE_CLEARANCE_Vendor%2FFeatureServer&source=sd

Table F24. Text Response Corresponding to Other Way of Sharing Roadway Restrictions.

Table F25 shows a summary of methods used to enforce OHV laws. Please note that one state can have multiple methods of enforcing OHV laws. According to the responses, the automated height measurement system at weigh stations is the only automated system used in OHV law enforcement by states who responded to the survey. The respondent from Delaware said that state does not specifically enforce OHV; however, if a truck is pulled over for speeding or another traffic violation, a complete CDL inspection is performed to confirm both driver and vehicle qualifications.

3. In-house systems or online resources (e.g., permitting system, web map, website, official social media) that are capable of information distribution.
4. CDL training.

Table F26. Responses about Communication with the Trucking Industry Regarding BrTS Issues.

When asked if a state has a procedure for identifying high-risk bridges or tunnels, 10 out of 19 respondents selected the option “Yes”, four selected “No”, and the remaining five selected “I do not know”. All states except for Indiana and South Dakota (who might not or didn’t take advantage of such data sources) said they use a stand-alone BrTS database and have developed their own risk assessment methods. The respondents from Kentucky and Wisconsin claimed that while there is a risk assessment method in place, their BrTS statistics are difficult to find. Overall, the data show that Kansas appears to have more BrTS crashes than other states, and also indicates having difficulty accessing BrTS statistics. They also have not developed a risk assessment method to identify bridges that are at a high risk of being struck by motor

vehicles. It should be noted that most of the recorded BrTS crashes in Kansas are categorized as scrapes. Table F27 shows all responses.

The next question is a follow-up question about a state’s response to a bridge/tunnel if it is struck repeatedly. Seventeen text entry answers were received and are summarized below:

1. Additional/advanced signages/control devices/overheight warning devices. (11)
2. Replacement priority, earlier rehab/replacement, or given additional strength in the repair. (7)
3. Lowering the pavement or increasing vertical clearance. (4)
4. Driver awareness education. (1)
5. Roadway geometry adjustment. (1)

Specific responses are listed in Table F28.

Table F28. Survey Responses of Agencies’ Strategies to a Bridge/Tunnel that is Struck Repeatedly.

The final question of the survey is a post-survey evaluation question aimed at obtaining further information from respondents regarding the project overall. Table F29 summarizes the responses.

Table F29. Summary of Post-Survey Comments with Opinions or Suggestions for the Study.

Conclusion

The survey findings reveal BrTS as a significant risk factor to public safety, causing damage to vehicles and infrastructures, injuries/fatalities, and costly delays for highway users. Unfortunately, the lack of comprehensive information on the number, location, and severity of BrTS hinders the identification of at-risk structures and the implementation of cost-effective countermeasures.

The survey offers valuable information for state agencies to improve their practices in preventing and mitigating BrTS incidents. These improvements include the need for a centralized data inventory system to manage BrTS information consistently and develop risk assessment methods to identify high-risk bridges/tunnels for BrTS. The survey also highlights important facts about BrTS statistics, policies, and operations, including underreporting, the highest estimated percentage of collisions by OHVs, and the common practice of using 3" less than the actual measured clearance on signage.

The survey data provides actionable steps for implementing measures to mitigate and prevent BrTS, such as additional signage, control devices, and driver awareness education. State agencies also use various levels and scales of involvement to communicate with the trucking industry regarding BrTS issues. The survey emphasizes the importance of these communications and the need for more comprehensive BrTS statistics as well as more accurate information such as lane-by-lane vertical clearance to prevent future incidents.

Overall, the survey provides valuable insights into the current practices and challenges surrounding BrTS prevention and mitigation efforts by state agencies. Further collaboration and data sharing are necessary to improve public safety on our highways and bridges.