Vehicle aware routing software: keep trucks and vans off low bridges and restricted roads
How to set up a vehicle profile, choose the software and know when the sign wins
Safety Behind the Wheel Foundation built this guide from Federal Highway Administration (FHWA) size, weight and bridge guidance, federal truck and hazardous materials regulations, Insurance Institute for Highway Safety (IIHS) data, state routing rules and National Institute for Occupational Safety and Health (NIOSH) research. Every source is listed at the end.
What vehicle aware routing software does
Many everyday navigation apps are built around a passenger car. They look for the fastest or shortest road. A box truck, tall van or tractor trailer needs the road it can actually use.
Vehicle aware routing software adds that missing piece. You enter a vehicle profile, which is a saved set of facts about the vehicle. These include its height, weight, length, width, number of axles and whether it hauls hazardous materials. The software compares the profile with road data and picks a route that fits.
It tries to keep you away from four kinds of trouble:
- Bridges and tunnels with less vertical clearance than your vehicle is tall. Vertical clearance is the open space between the road and the lowest part of the structure overhead.
- Bridges and roads with posted weight limits.
- Streets with turns or lanes too tight for a long vehicle.
- Roads or tunnels closed to trucks or to certain cargo.
The stakes are real. In 2024, 5,340 people died in large truck crashes, and 62% of them were in cars and other passenger vehicles [1]. IIHS counts any vehicle with a gross vehicle weight rating over 10,000 pounds as a large truck [1]. That rating is the most the maker says the vehicle can weigh when loaded.
A bad route can end in a bridge strike, which happens when a vehicle taller than the clearance hits the structure. Faulty directions, whether from a dispatcher or from a navigation unit, can put a driver on that road. No software can promise to prevent a strike. Treat it as a strong aid, not a proven cure.
Who uses it and where it helps most
Delivery firms, service fleets, trucking companies and shuttle or rideshare operators are the usual buyers. The fleet owner or manager picks and sets up the software. Road agencies, not fleets, post the signs it must respect.
Here are common places where it earns its keep:
- Roads with lower posted clearances. The state limit is not the only number. Individual roads can post less [2], and software that stores those figures can steer you around them.
- Tall service vans. A ladder rack or roof vent can add inches that nobody wrote down.
- New or relief drivers. They do not know the local trouble spots, and a shortcut can lead onto a bridge posted for a lower weight.
- Placarded loads. A placard is the diamond shaped sign that tells responders which hazard a vehicle carries. These loads face special route rules [7].
- The last few blocks. Customer sites often sit on narrow streets or in tight yards.
- Rail crossings. Low vehicles can get stuck on humped crossings. See railroad crossing safety.
The limits your software has to know
Routing software is a messenger for rules that other people write. This table shows who sets what.
Comparison compiled by Safety Behind the Wheel Foundation
Who sets each route limit
| Limit | Who sets it | What the software needs from you |
|---|---|---|
| Height | States set truck height limits, and bridge owners sign lower clearances [2, 3] | Real height, with everything on the roof |
| Weight | Federal limits on total and axle weight, plus lower limits posted by bridge owners [4, 6] | Loaded weight, axle count and axle spacing |
| Width | A federal width rule on the National Network [4] | Vehicle and trailer width |
| Hazardous materials | Federal carrier duties plus state or tribal route designations [7] | Placard class and trip details |
Height and weight
There is no federal height limit for commercial vehicles. States set their own [2, 3]. An FHWA compilation reported state limits running from 13.6 to 14.6 feet [3]. Individual roads can be lower, because lower clearances are allowed on particular roads [2]. That is why the sign on the bridge matters more than the state number. Safety Behind the Wheel Foundation urges every driver to treat the posted clearance as the rule, whatever the screen shows.
Federal truck rules set 80,000 pounds as the top gross vehicle weight. Single axles top out at 20,000 pounds. Tandem axles, which are two axles set close together, top out at 34,000 pounds. A lower total applies when the bridge formula says so [4]. The formula looks at the number of axles and the distance between them, because spreading weight out puts less stress on a bridge [5].
Bridge owners must also post a weight limit when legal loads exceed what a bridge’s load rating allows. Federal inspection rules say the sign must go up as soon as possible, and no later than 30 days after the rating shows the need [6]. A new sign shows up on the road first. Map data may trail behind it.
Width, access and the last mile
The federal width rule is 102 inches on the National Network. That is the network of highways in each state where the larger trucks allowed by federal law may operate [4]. Federal rules also protect reasonable access from that network to terminals and to services such as fuel, food, repairs and rest [4]. That access does not make every side street safe for a long trailer.
Hazardous materials
Carriers that haul placarded, nonradioactive hazardous materials must follow route designations set by states and tribes. These can include curfews, lane limits, route bans and weight limits on routes [7]. States must weigh bridge clearances and vehicle size and weight limits when they pick routes [7].
Carriers must also avoid routes through or near heavily populated areas, crowds, tunnels, narrow streets or alleys. The exceptions are no practical alternative, a reasonable detour to a terminal or to services, and emergency or police direction. Operating convenience does not count as a practical reason [7].
A state route takes effect only after FMCSA publishes it in the National Hazardous Materials Route Registry [7]. The federal definition of a motor carrier includes the employees who assign and dispatch drivers [7]. So routing duties reach the dispatch desk, not just the cab.
State examples: why one national map is not enough
Three states show how rules differ on the ground.
- New York designates “qualifying highways” and “state access highways” for larger trucks and trailers. Its rules list which vehicle combinations may use them, with limits on length and width [8].
- Texas handles oversize and overweight loads through permits. The state motor vehicle department picks the most practical route using TxDOT information. It weighs vertical clearances, width limits, steep grades and bridges or roads with load limits [9]. For the very largest loads, the applicant must inspect the route in person unless TxDOT has granted an exception based on a route study [9].
- Colorado State Patrol rules cover the permitting, routing and transport of hazardous and nuclear materials. They include a part on hazardous materials route designation [10].
A fleet that crosses state lines faces all of these. Ask how fast the software picks up new designations.
Measure the vehicle first
A profile is only a guess until someone checks it. Use this routine for every vehicle.
- Measure the tallest point with the vehicle loaded and parked on level ground. Count roof racks, vents, air conditioners, antennas and beacon lights.
- Measure again after any change, such as a new rack, new tires or a different trailer. An empty vehicle usually rides higher than a loaded one.
- Record the loaded gross weight. Use a scale ticket when you can, not just the maker’s rating.
- Count the axles and measure the distance between them. The bridge formula looks at both [5].
- Record overall length, including the trailer, hitch and any cargo that hangs past the bumper. Record the full width too.
- Enter the hazard class for any placarded load.
- Write down the date and who measured. Keep a card in the cab and add a profile check to the pre trip routine.
Then add a margin. If your vehicle stands 13 feet 2 inches tall and a sign says 13 feet 3 inches, treat that bridge as closed to you.
Choosing software and where to get it
Fleet technology suppliers sell this software, usually as a monthly or yearly subscription. It may come as an in cab device, a phone or tablet app, or part of a dispatch platform that sends routes to drivers. Installation can be as simple as mounting a device and signing in. It can also mean linking the tool to the vehicle’s data system, which a supplier or equipment installer can do.
The fleet owner or safety manager should choose it. Test any product on routes you already know are tricky.
Using it every day
The setup rules in the guide to using GPS navigation safely apply to trucks too. Set the route before the vehicle moves, and keep glances short.
- Pick the right vehicle profile. This matters most when several vehicles share one device.
- Preview the whole route while parked, including the last few blocks.
- Ask the customer about gates, docks, height limits and a safe place to turn around.
- Follow the sign, not the screen. If a sign shows less clearance or a lower weight than your profile, obey it. Find a safe place to stop before you reroute.
- After a missed turn, let the software recalculate. Do not make a sudden move or back up on the road.
- Tell dispatch about any mismatch between the screen and the road.
People matter as much as the software. A NIOSH study of in vehicle monitoring found that feedback in the cab plus supervisor coaching with video cut risky driving compared with a control group. Feedback alone did not [12]. That tool is different, but the lesson likely carries over. Drivers also need training on the routing software itself, and a clear way to reach dispatch when the screen and the road disagree. See fleet telematics and coaching for how to build that habit.
Where it falls short
Even a good system has blind spots.
- A wrong profile. A new roof rack or a different trailer makes the stored height wrong.
- Old or missing data. A new sign, closure or weight posting can reach the road before it reaches the map. Ask the supplier how it gathers restriction data and how fast it updates.
- Places the map does not cover. Private roads, loading yards and parking lots may have no restriction data. A closed lane or detour may not show up yet either.
- Two apps at once. A driver who switches to a general phone app can undo every protection.
- Trusting the screen over the sign. This is the mistake that ends in a bridge strike.
For weather and breakdown planning, see journey management for work drivers.
Keeping it working
Treat the software like other safety equipment, with a schedule.
- Every month: install updates and confirm that each profile still matches its vehicle. Update it at once after any change, such as a new rack or body.
- Every quarter: compare planned routes with driven routes. Spots where drivers keep deviating often show a data error.
- Each year: retrain drivers and dispatchers, and ask the supplier about its data sources again.
If a bridge strike happens, stop in a safe place, turn on the hazard lights and tell dispatch. Call 911 if anyone is hurt or lanes are blocked. A strike can harm a bridge in ways that are not obvious from the road, so the bridge owner needs to inspect it. Report every strike, even when the vehicle looks fine.
What residents, school boards and local officials can do
Public warning signs belong to the agency that owns the road. The national manual for traffic signs and signals, the MUTCD, is now in its 11th Edition with Revision 1, dated December 2025 [11]. Residents should never install their own signs.
You can still help:
- Report missing, damaged or hidden signs near a low bridge, a weight posted bridge or a truck restricted street. Contact the state transportation department for state roads, or local public works for city streets.
- Give the exact location, photos and dates of any strikes or near misses.
- Ask the agency to review advance warning signs ahead of low clearance bridges, humped rail crossings and weight restricted routes.
- Ask whether the agency shares its restriction data with mapping companies.
Frequently asked questions
Is a regular phone navigation app enough for a box truck or tall van?
Not by default. Many everyday apps are built around cars and choose the fastest road, so they may not know your vehicle’s height or weight. If an app lets you enter vehicle details, test it on known tricky routes first. Even then, the signs come first.
Does routing software make a hazardous materials trip legal?
No. Software can help you follow routes, but the carrier stays responsible. A designated route takes effect only after FMCSA lists it in the National Hazardous Materials Route Registry [7]. A vehicle carrying hazardous materials must also follow the laws of each jurisdiction it enters, unless a federal rule is stricter [7].
What if the app says go and the sign says no?
Follow the sign. Apps can use old data, and the sign shows the road owner’s current rule. Find a safe place to stop, reroute, and tell dispatch so the error can be reported to the supplier.
What should a driver do after hitting a low bridge?
Stop in a safe place, turn on the hazard lights and tell dispatch. Call 911 if anyone is hurt, the structure looks damaged or lanes are blocked. Stay until officers say you may leave. The bridge owner needs to inspect the structure, so report every strike.
How can a resident ask for better warning signs near a low bridge?
Contact the agency that owns the road. Describe the location, attach photos and list the dates of any strikes. Ask for a review of advance warning signs and truck route signs. Do not put up your own signs.
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Safety Behind the Wheel Foundation encourages every fleet to pair routing software with an accurate vehicle profile and a firm rule that the posted sign always wins. Vehicle aware routing software is a useful safety layer for any fleet with tall, heavy or long vehicles. It cannot measure your vehicle, read a new sign or take on legal duties for you.
Start with an accurate profile, add a margin, and teach drivers that the sign always wins. Then keep the system current, collect reports of bad data and share problem spots with the road agency.
Related articles
Sources and further reading
- 1Insurance Institute for Highway Safety (IIHS). Fatality Facts 2024: Large trucks. Posted June 2026. Data year: 2024. iihs.org/…/large-trucks
- 2Federal Highway Administration (FHWA). Federal Size Regulations for Commercial Motor Vehicles (FHWA-HOP-04-022). Published October 2004. ops.fhwa.dot.gov/…/index.htm
- 3FHWA. Compilation of Existing State Truck Size and Weight Limit Laws. Published May 2015. Data year: 2015 (state laws as compiled). ops.fhwa.dot.gov/…/index.htm
- 4Electronic Code of Federal Regulations (eCFR). 23 CFR Part 658, Truck Size and Weight, Route Designations – Length, Width and Weight Limitations. Up to date as of October 1, 2026. ecfr.gov/…/part-658
- 5FHWA. Bridge Formula Weights (FHWA-HOP-19-028). Published August 2019. ops.fhwa.dot.gov/…/index.htm
- 6eCFR. 23 CFR 650.313, Inspection procedures (load rating and load posting). Up to date as of September 30, 2026. ecfr.gov/…/section-650.313
- 7eCFR. 49 CFR Part 397, Transportation of Hazardous Materials; Driving and Parking Rules (sections 397.3, 397.65, 397.67, 397.71 and 397.73). Currency dates September 9 to October 2, 2026. ecfr.gov/…/part-397
- 8Legal Information Institute, Cornell Law School. N.Y. Comp. Codes R. & Regs. Tit. 17 section 8000.7, Authorized vehicles and Chapter VII, “Highways designated for use by trucks, tandem trailers and other special dimension vehicles.” Accessed October 2026. law.cornell.edu/…/17-NYCRR-8000.7
- 9Legal Information Institute, Cornell Law School. 43 Tex. Admin. Code section 219.11, General oversize/overweight permit requirements and procedures. Accessed October 2026. law.cornell.edu/…/43-Tex-Admin-Code-SS-219-11
- 10Legal Information Institute, Cornell Law School. 8 CCR 1507-25 (Colorado State Patrol), The permitting, routing and transportation of hazardous and nuclear materials and the intrastate transportation of agricultural products. Effective April 30, 2007; amended through March 31, 2023. law.cornell.edu/…/8-CCR-1507-25
- 11FHWA. Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1. Dated December 2025. mutcd.fhwa.dot.gov/kno_11th_Editionr1.htm
- 12National Institute for Occupational Safety and Health (NIOSH), CDC. Newsroom Feature: In-vehicle Monitoring Systems. Updated June 7, 2021. archive.cdc.gov/…/in-vehicle.html
This article reflects the safety priorities of commercial vehicle routing and bridge strike prevention. It is general education, not legal, insurance or financial advice. Height, weight and hazardous materials rules change, so verify details with official sources and the signs on the road. For your own situation, contact your state transportation department, your state motor carrier office, the Federal Motor Carrier Safety Administration, your insurance professional and your software supplier. Reviewed October 2026.
Cite this article: Safety Behind the Wheel Foundation. “Vehicle aware routing software: keep trucks and vans off low bridges and restricted roads.” drivewithcare.org, https://drivewithcare.org/vehicle-aware-routing-software-low-bridges-weight-limits/. Reviewed October 2026.
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