November 22, 2014
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How Do Buses Handle Potholes?

"12 Teal" "Orchard Downs" "winter"

The 12W Teal departs Orchard Downs as it serves cold and snowy streets.

The short answer – not well. While smaller transport modes like cars and bicycles can nimbly dodge these winter traps, large vehicles like garbage trucks, 18-wheelers, salt trucks, and buses cannot. Thankfully, the record ridership we’re seeing is taking more vehicles off the road as passengers opt for a shared ride.

Our area has seen heavy snowfalls and plummeting temperatures throughout this winter season and the roads reflect the numbers. Most roads around Champaign-Urbana are pocked, cracked, and demand vigilance.

“While buses, and every other vehicle on the road, do contribute to the wear and tear of our roads – we’re seeing a whole different aspect to the production of pot holes this year,” says Karl Gnadt Director of Market Development/Managing Director Designate. “The extreme temperatures we’ve experienced along with higher amounts of precipitation have really destroyed the pavement. In addition to that, the standards of the various infrastructures really come into play. Many roads in our community may meet minimum standards, but don’t meet what the environment demands.”

An Ode to the Leveling Valve

Operators are forced to stay on course when approaching a pothole for the safety of our passengers and surrounding traffic. Some may think our big buses and tires would easily roll over potholes,  but that’s not always the case. The bus part that suffers the most in a pothole interaction is the leveling valve.

The leveling valves are responsible for leveling the bus. There are air bags on every corner of the bus and the air within them control many things including the brakes, doors, and driver’s seat. The leveling valves respond to the demand of their surroundings because they’re connected to the bus axles as well as the frame. As needed, the leveling valves release air from the air bags (as well as take air in) in order to keep the bus level with the axles.

But when a bus rolls into a pot hole, the wheel is forced down into the road but the body of the bus stays level. The leveling valve link, being connected to the axle and the body, is forced to go two directions at once. And because that’s impossible, it can snap. The leveling valve disconnects and air is released from the air bag. The bus is left with a serious limp and must be taken out of service.

"bus storage" "extra buses"

MTD needs extra buses when scheduled service comes up, to train new operators, and for the unexpected like potholes.

Comes With the Territory

In most instances, the buses can be driven back to our Maintenance Department very slowly. Sometimes an MTD tow truck is required to haul the vehicle back. Either way a replacement vehicle is required and servicing must occur. If only the leveling valve needs replacement, service time is about 30 to 45 minutes.

“This time of year, we always keep extra leveling valves in stock,” says Dave Moore Maintenance Director. “We usually don’t have these issues until later in the winter season, but this year we’re up 25% of cases like this.”

Thanks to the area’s public works departments for getting the potholes filled. It is a major undertaking this season and added stress to the demand of snow removal and salting.

How do you think MTD is handling this treacherous winter? Are you riding the bus more this season?

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About Amy Snyder

Amy Snyder is the Customer Service Manager at the Champaign-Urbana Mass Transit District. She writes and manages content for this blog, The Inside Lane, as well as the social media pages for CUMTD.
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4 Responses to How Do Buses Handle Potholes?

  1. Sue Jones says:

    I’m riding the bus about 20 times as much as ever before. Most I’ve used it before was 6 times over the winter. Either things were so bad I didn’t have to go *anywhere,* or it was just cold. One winter that had some bad stuff timed it so it was on weekends or holidays.
    Gotta say it was no fun last Thursday watching the little light say the bus would be there… counting down to “due,” and then two busses arrived and dropped people off but had their NIS lights on… so it was 20 minutes from “due” before we boarded… but we were waiting *inside*, not out in the cold and snow, so while it wasn’t fun, it wasn’t miserable, either, and I’m confident CUMTD was doing the best it could.

  2. Amy Snyder says:

    Thanks for sharing your experience, Sue, and for being patient with us. Severe weather has increased demand, which has put some strain on the system recently. This is a great problem to have and employees in all departments are rising to the occasion. Thank you for riding.

  3. Siyao Luan says:

    Good article Amy!
    One thing to point out: air bags are not air reservoirs (or air tanks). Air bags are on each axle, and they are the springs of the suspension system. Air inside them is fed by the air reservoirs. The entire pneumatic (or compressed air) system in a bus is somewhat integrated, but functions (almost) separately, sharing only the compressor, dryer and reservoirs as the source of all compressed air. Air that went inside air bags truly no longer operates brakes, doors, driver seat, wipers, etc. If these systems demand compressed air, they draw it from the reservoirs, not the air bags.

    But anyway, very good article! I’ve read almost all “the Inside Lane” articles and found them really interesting. Want to read more!

    • Amy Snyder says:

      Thanks for the detailed clarification, Siyao! Writing about these technical issues demands research and I appreciate the help and education. Thanks for reading.

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Champaign-Urbana Mass Transit District
1101 East University Avenue
Urbana, IL 61802-2009
(217) 384-8188
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