A big bowl of concerns

July 19, 2002

Roadwork zones induce problems to the traffic flow, decreasing the level of safety. A number of factors come into play including: the type of work, type of road, volume, composition and speed of traffic flow, road alignment, weather conditions and visibility.

Roadwork sites increase accident rates and the severity of those accidents.

Roadwork zones induce problems to the traffic flow, decreasing the level of safety. A number of factors come into play including: the type of work, type of road, volume, composition and speed of traffic flow, road alignment, weather conditions and visibility.

Roadwork sites increase accident rates and the severity of those accidents.

Reducing this problem requires an integrated and systematic approach aimed at identifying and solving the safety problems of the work zone. An effective approach, which is quickly spreading at the international level, is the work-zone safety audit in both urban and rural areas. The audit is a formal examination of a future road or traffic project, an existing road or any project that interacts with road users. An independent, qualified team reports on the project’s potential accident and safety performance.

In countries such as Italy, where there are no work-zone standards or guidelines related to traffic management and safety aspects, such a procedure may be beneficial in providing a general safety improvement.

The audit team applies the principles of road safety according to a multidisciplinary perspective, taking into account the needs of all road users: car drivers, pedestrians, cyclists, motorcyclists, children, elderly people, people with disabilities, truck and bus drivers and public transportation users.

The objectives of a safety audit at work zones are:

                To identify potential safety problems for road users and others; and

                To ensure that measures to eliminate or reduce the identified problems are fully considered by the client and those involved in construction, maintenance or any other road activity which may affect normal operating condition of the road.

Just their opinions

The road safety audit is aimed at identifying and solving risk factors by trying to investigate how the road environment is perceived and ultimately utilized by different road users. Part of the analysis involves a comparison process between the opinions expressed by a team of safety specialists. The audit procedure includes the involvement of the following figures:

Client

The client commissions audits at proper project stages, selects an audit team with the appropriate training and experience, reviews the formal audit report and acts upon recommendations whenever appropriate and feasible.

Designer

The designer is responsible for the traffic management scheme and provides the audit team with all the background information to the scheme. This person also responds to initial audit findings.

Audit team

The team should be made up of more than one person and should have adequate experience in road safety engineering and practices, accident in- vestigation and prevention, traffic engineering and road design.

The work-zone work flow

Work zones are dynamic environments. Therefore, it is vital for the audit process to be a quick mechanism to identify and correct unsafe conditions.

The main steps of the safety audit are:

                Client selects the audit team;

                Designer provides necessary documents to audit team;

                A preliminary meeting be-tween all subjects involved is carried out and audit objectives and procedures are set;

                The team examines all project documentation and drawings;

                The team conducts site in-spections, both in daytime and nighttime and both as motorists and pedestrians;

                The team then reviews the results of the site inspections and documentation analysis. Checklists, photographs and videos are a useful prompt for the auditors. The team singles out potential accident scenarios by prediction of accident types and their contributing factors, and defines possible countermeasures;

                The team writes the safety audit report, in “problem/recommendation” format, where the problem is described in terms of an accident risk to a road user and the recommendation is an engineering solution to the reported problem. Recommendations produced by the audit team should indicate the type of measures without specifying detailed technical issues;

                A completion meeting between all subjects involved is held and the proposed recommendations are examined and discussed;

                The designer reviews the audit report and communicates to the client any and all observations;

                The client examines the audit report and the designer’s observations and decides about the implementations of the recommendations; and

                The client responds to the audit report by writing an exception report.

Safety audits also should be done at the end of work-zone installation, during work through repeated, unannounced site inspections and after work-zone removal to verify if the risk factors caused by the work zone still exist.

The audit team only examines aspects influencing user safety, but it doesn’t consider other elements, which can refer to other judgment criteria unrelated to safety. Therefore, the team should analyze, for example, if users correctly perceive the work zone not only during the day but at night and in bad weather conditions as well. If there is a high pedestrian flow, the analyst should simulate all the scenarios in which different types of pedestrians (i.e., an elder with walking difficulties or a child) who could be covered by signals or work-zone equipment.

What made the list

Checklists are used so the audit team does not overlook important safety problems. Checklists are not a substitute for knowledge and experience, and should only be used as an aid. A checklist specifically suited for work zones is split into five sections.

Traffic management

Work zones may induce rerouting of road users in the network. Characteristics of the road network affected by the work zone have to be analyzed, taking into special consideration vulnerable road users.

Work-zone layout

Work zones consist of five areas: advance warning, transition (usually one of the most critical issues for work-zone safety), buffer (which provides a longitudinal and lateral recovery for motorists and workers), traffic and termination.

Signs and lighting

The road system must provide adequate visual information to enable the driver to adapt his behavior to the work-zone conditions and also enable the pedestrian to safely walk to the intended destination. Permanent and temporary signs and markings must correctly interact with each other.

Roadside obstacles

In work zones, many accidents involve the vehicle leaving the road. Longitudinal safety barriers, their transitions and terminals should provide adequate protection to roadside obstacles.

Work-zone operations

Interaction between work activities and traffic flow may be an accident-contributing factor, especially if the buffer area is insufficient.

A risk’s worth

A problem’s magnitude may be quantified by conducting risk assessments. Various risk assessment procedures can be used.

The easiest approach involves the audit team prioritizing the safety issues based on experience, but this method is somewhat subjective.

A more objective approach involves the prediction of the frequency and severity of potential accidents associated with each problem identified in the audit report. A risk assessment matrix, where the risk score depends on both the frequency and severity of potential accidents, may be used.

The auditors would go through the report and give each problem a risk score, making their assessments of risk if nothing is done. Then, the auditors would go back through their recommendations and, making the assumption that the recommendation will be carried out, reassess the risk. With this procedure, the team not only looks at the existing road, or project, deficiencies but also takes into account that those problems could produce road accidents and that the suggested improvements may reduce the accident consequences.

Pilot errors

Pilot work-zone safety audits have been performed both in urban and rural areas. A team of two inspectors inspected each site twice—day and night. The visits were not announced and work-zone drawings were not available.

The safety audits identified many problems. Fixing those problems required low-cost safety measures such as the insertion of longitudinal and transverse buffers, better markings and signing, the adjustment of road restraint systems and the construction of pedestrian facilities.

Urban audit

Two work zones in Naples, Italy, were inspected. In the first site, the work zone occupied a three-way intersection and was located on a sharp bend. In the second area, the work zone took up one of the two lanes, with alternate one-way traffic managed by signals. 

Many traffic management problems were encountered, most involving the formation of queues. In the first work zone, there was a problem with a queue at traffic lights. Vehicles arriving at the lights could not see the queues because of the presence of a bend. Furthermore, in the bend there is a work-zone sign (“We are working for you”) in the center lane that compels the users to divert to the outer lane, causing the potential for head-on accidents. Similar problems were encountered in the second work zone, where work-zone warning signs were absent. Both sites also lacked a safe route for pedestrian traffic.

The work-zone layout is usually the most relevant safety aspect. Here, the work zones scored failing grades because there was a lack of both longitudinal and transverse buffer areas and the configuration of the traffic areas was wrong.

Signage and lighting was another trouble spot. In most cases there was a lack of warning signs and markings, and the existing signs and markings carried the wrong color and didn’t provide adequate information to the user. Sign maintenance also was poor and there was a lack of delineation along the path of the work zone.

The roadside obstacle safety level was equal to an ‘F’ because the zones lacked safety barriers, and in several cases open excavation was not blocked by any kind of protection device or restraint system.

A common problem in work-zone operations was the work was carried out very close to the traffic flow. Accesses to the work place also were positioned in dangerous areas.

Rural audit

A third work zone was a two-lane rural highway located in Pozzuoli, Naples. It consisted of the roadside and part of one of two lanes and caused the narrowing of both lanes. A fourth work zone was on the A3 Naples-Salerno motorway and included a succession of work zones.

Problems in the rural zones were similar to the ones found in the urban environment. The main difference was a faster travel speed, which increases both the number and severity of accidents.

On the motorway there were many problems related to the limited road capacity. Congestion problems caused many users to use adjacent roads with lower geometrical and functional characteristics. As a result, road accidents could have increased.

Buffer areas were generally absent in the rural areas, too. There was a lack of work-zone alert signs, incorrect horizontal markings and signs out of position. On the motorway, signs were often positioned in the wrong way. There also was a coexistence of permanent and temporary markings, which could have led to driver confusion.

Roadside obstacle problems were common to both the urban and rural areas. In the motorway a common problem was the absence of separation between traffic moving in the opposite direction.

About The Author: Montella is assistant professor, University of Naples, Naples, Italy. Ciotola is an engineer with TMS Consultancy Italy, Pozzuoli, Italy.