LOW-COST ROAD IMPROVEMENTS By JOHN W. McCREE Bureau of Local Roads and Streets, IDOT

The vast majority of the nation's highway system consists of two-lane roads (both rural and urban) carrying relatively low traffic volumes — average daily traffic (ADT) of less than 400 vehicles per day. A substantial amount of these two-lane roads (based on mileage) experience operational and safety problems caused by inadequate road geometry, driver information deficiencies, lack of passing opportunities and/or traffic conflicts due to turning movements at intersections and driveways. These operational problems on two-lane highways are irritating and cause driver delays. Drivers are prevented from traveling at their desired speeds by slower traffic, turning movements and/or highway alignment. Delays result in lost time and driver frustration which escalate the safety problems.

A recently completed FHWA study indicated that approximately 34 million motor vehicle accidents can be expected to occur over the next 20 years on two-lane low volume roads unless positive action is taken to correct the problems responsible for many of these accidents. This large number of estimated accidents should be of concern to all those responsible for operating and maintaining these two-lane roads since each accident represents a potential tort action.

As an alternate to extensive highway realignments, construction of four-lane divided highways, provisions for access control and major intersection improvements, many operational and safety problems can be remedied by low-cost improvements. In many cases, it is generally more cost-effective to improve passing opportunities and to reduce problems caused by turning vehicles than to completely reconstruct existing roads.

Low-cost passing improvements include passing lanes in level and rolling terrain, climbing lanes on sustained grades, short four-lane sections for localized problems, turnouts and continuous paved shoulders to

COMPARISON OF OPERATIONAL AND SAFETY IMPROVEMENT ALTERNATIVES FOR TWO-LANE HIGHWAYS
Improvement Alternative	Improvement Type (Passing or Turning)	Relative Cost	Operational & Safety Benefits       Travel Time        Traffic Accidents
Four-lane divided	Both	High	Reduction	Reduction
Realignment	——	High	Variable effect	Reduction
Access control	Turning	High	Negligible	Reduction
Grade separation	Turning	High	Negligible	Reduction
Passing lanes	Passing	Moderate	Reduction	Reduction
Turnouts	Passing	Low	Small Reduction	——
Shoulder driving	Passing	Low	Small Reduction	——
Left-turn & right-turn lanes	Turning	Low	Small Reduction	Reduction
Two-way left-turn lanes	Turning	Low	Small Reduction	Reduction
Shoulder bypass lanes	Turning	Low	Small Reduction	Reduction
Road Signing	——	Low	Negligible	Reduction

April 1988 / Illinois Municipal Review / Page 19

encourage shoulder driving where and when allowed by law. Low-cost turning improvements include left-turn and right-turn lanes at intersections, turn bypass lanes at T-intersections and continuous two-way left-turn lanes (July 1987 Issue). The improvement of road signs and markings to inform drivers about changes in road geometry and traffic operating conditions is another low-cost method used to enhance the quality of service experienced by the driver. This will also eliminate a large number of potential accidents.

Several methods are available for assessing the effectiveness of proposed highway improvements and for determining whether such improvements are warranted for a given road and traffic volume. Low-cost improvements should be evaluated using operational criteria, level of service criteria, cost-effectiveness analysis and benefit-cost analysis prior to scheduling.

In a period of rising construction costs and tightening financial constraints, local governments need to utilize these cost-effective alternatives to ensure the greatest possible return on their investment. The alternatives presented often realize at much lower costs many of the same benefits major realignment and widening improvements provide as indicated in the table below. Improvement strategies utilizing passing lanes, turn lanes and other low-cost improvements lead to widespread improvements on many roads rather than extensive reconstruction of a few roads. This approach will provide a better and more uniform quality of service over the entire low volume road network and can offer a means for quick response to perceived needs. •

Page 20 / Illinois Municipal Review / April 1988