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Al You describe a very challenging transportation problem. I assume that it is not practical to upgrade the road structure for summer use so you are very much tied to vehicle technology options. If traction is a problem then you need to select a drive suspension that is highly flexible especially in the lateral dimension in order to achieve equalization of vertical wheel loads (left - right). Air suspensions are probably not a good choice because the auxiliary roll stiffness on a per axle basis is very high which will result in significant left-right vertical wheel load imbalance on uneven terrain. Rock out-croppings will be hard on tires but research has shown that reducing tire air pressure will significantly reduce tire punctures even from the aggressive Canadian Shield rock formations. I believe that dual tires will be the best choice for this application and you may want to experiment with less aggressive tread traction characteristics if low tire pressures are to be used. This may help preserve the road surface characteristics especially in poor soils. This is a hunch of mine so please consider this option carefully before trying it out. The final bit of advice has to do with operational considerations. It is well known that moisture is the "Achilles heel" of the road maintenance engineer. You may want to consider closing the road during wet weather and spring thaw. I hope these ideas help. You may contact me at (613) 253-8858 if you have further questions. John -----Original Message----- From: The list is for the use of academics and others interested in technical, op [mailto:[log in to unmask]]On Behalf Of Bradley, Allan HI0 Sent: December 13, 2000 3:55 PM To: [log in to unmask] Subject: Enhancing commercial vehicle traction on sandy roads Hello colleagues, I am writing to see whether someone can suggest some solutions to a transportation challenge that we have here in Saskatchewan, Canada. Our Highways Department recently opened a winter road of about 150 km length to improve access to the far north of the province. The locals have decided that they want to try using the road during the summer at slow speed (<50 km/h). However, commercial trucks with standard tires and wheels are having difficulty negotiating the rocky outcrops and pockets of sand (typical Canadian Shield landform). Can anyone suggest any technologies that might be tried to increase the mobility of the commercial trucks on this run? My thoughts so far are: reduced tire pressures (Tire Pressure Control System-controlled) Super single tires Sand/All Terrain traction tires like the Michelin XS or XL 18R22.5 or Goodyear 445/65R22.5 G178 Thanks for your assistance with this. Al.\\