(a) The commissioners court shall apportion the part of the cost of an improvement assessed against abutting property among the parcels of the abutting property and the property's owners in accordance with the front foot rule.
(b) If, in the opinion of the commissioners court, application of the front foot rule would result in injustice or inequity in a particular case, the commissioners court may apportion and assess the cost in the proportion the commissioners court determines just and equitable to produce a substantial equality of benefits received and burdens imposed.